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A microprobe study of placer gold and its origin in the lower Fraser River drainage basin, B.C. Knight, John Bruce 1985

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A MICROPROBE STUDY OF PLACER GOLD AND ITS ORIGIN IN THE LOWER FRASER RIVER DRAINAGE BASIN, B. C. by JOHN BRUCE KNIGHT B.Sc, The University Of Cape Town, 1972 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES Department Of Geological Science We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA February 1985 © John Bruce Knight, 1985 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y of B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head o f my D e p a r t m e n t o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f G e o l o g i c a l S c i e n c e The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5 D a t e : 18 F e b r u a r y 1985 Abstract The compositions, in terms of Au, Ag, Cu, and Hg, of about 1200 placer and lode gold grains from the Fraser River drainage were determined by microprobe analysis. The lode samples are from the Bralorne and Cariboo Gold Quartz mines. Seventeen placer samples are from the Cariboo d i s t r i c t and the Bridge River, Fraser River and the i r t r i b u t a r i e s . Bralorne gold and many placer grains contain Hg which ranges up to 6%. Evidence i s presented to show that this Hg i s primary. Placer gold grains also contain Cu, ranging up to 31%, but high-Cu gold has l i t t l e Ag or Hg. The compositional data were used to define populations on Hg-Cu-Fineness plots for each sample location. A comparison of the populations shows that placers located near lodes r e f l e c t these sources but that simple downstream transport of the gold cannot explain the populations found far from known sources. In order to explain the population found in downstream placers i t is necessary to postulate contributions from undiscovered lodes, f o s s i l placers, or other unknown sources. Many placer grains from the Fraser River have rims that are nearly pure gold. The rimming i s thought to have taken place in an "intermediate c o l l e c t o r " ( f o s s i l placer?) by leaching of Ag. Rimmed gold i s not found in the Bridge River. From the data on the composition of the gold one i s able to divide the Fraser River drainage into two metallogenic provinces: a Cu-Hg-rich province that includes the Bridge River drainage and a Cu-Hg-poor province t y p i f i e d by the Cariboo r e g i o n . The d a t a from t h e l o d e d e p o s i t s s u g g e s t t h a t t h e d e p o s i t s c a n n o t o n l y be u n i q u e l y c h a r a c t e r i s e d but t h a t i t may be p o s s i b l e t o d i s t i n g u i s h z o n i n g w i t h i n t h e l o d e s . In a d d i t i o n , f i t a p p e a r s t h a t much of t h e Cu- and H g - r i c h g o l d i s a s s o c i a t e d w i t h u l t r a b a s i c r o c k s and major f a u l t s . i v TABLE OF CONTENTS Page ABSTRACT i i LIST OF TABLES v i LIST OF PLATES v i i LIST OF FIGURES v i i i ACKNOWLEDGEMENTS ix INTRODUCTION 1 PREVIOUS WORK 1 Phase Diagrams 5 METHODS 6 SAMPLE COLLECTION 6 SAMPLE PREPARATION 6 SAMPLE ANALYSIS 7 Instrument Setup 7 An a l y t i c a l Procedure 8 Accuracy 9 Precision 10 Homogeneity 11 DATA PREPARATION 11 SAMPLING RELIABILITY 13 TEXTURE 7 16 GRAIN SHAPE 16 INCLUSIONS AND STAINING 17 RIMS 18 Hg Rims 23 V DISCUSSION 25 GOLD GROUPINGS 25 INTRODUCTION 26 AREA 1, CARIBOO 28 Samples 28 Lode 28 Placer 29 Interpretation 29 AREA 2, BRIDGE RIVER 29 Source Samples 29 Lode 29 Placer 30 Downstream Samples 31 Interpretation 32 AREA 3, FRASER RIVER 36 Downstream Samples 36 Interpretation 38 SUMMARY OF THE HISTORY OF PLACER TRANSPORT 43 SOURCES-SPECULATIONS ABOUT THE LODES 44 CONCLUSIONS 51 REFERENCES 53 ~ v i L I S T OF TABLES T a b l e Page 1 : Sample D e t a i l s 58 2 : E l e m e n t L i n e s and A n a l y t i c a l C r y s t a l s 61 3 : S t a n d a r d s 61 4 : D e t e c t i o n L i m i t s a t 99% C o n f i d e n c e f o r 1 A n a l y s i s ...62 5 : C o r e - C o r e D u p l i c a t e s 63 6 : C ore-Rim D u p l i c a t e s 66 7 : F i n e n e s s C o m p a r i s o n 68 8 : Rim-Core C o m p o s i t i o n s 69 9 : Hg C o n t a m i n a t i o n T e s t 71 10 : Rim D i s t r i b u t i o n 72 1 1 : Lode G o l d 73 v i i LIST OF PLATES Opposite page Plate 1a : AU48-2 i s an example of angular, unflattened grains , ( ref lected l i g h t image) 74 1b : AU52-2 i s an example of smooth, f lattened gra ins , ( re f lected l i g h t image) 74 Plate 2a : AU52-3-6 shows the smooth contact between core and rim, (backscattered e lectron image). . . . 7 6 2b : AU52-2-9 shows the smooth contact between core and rim, (backscattered e lectron image). . . . 7 6 2c : AU52-5-15 shows the smooth contact between core and rim, (backscattered e lectron image). . . . 7 6 2d : AU52-1-18 shows high fineness gold along cracks , (backscattered e lectron image) .76 Plate 3a : AU52-1-21 shows high fineness gold along cracks , (backscattered e lectron image) 78 3b : AU52-4-26 shows the uniform thinness of the rim on s tra ight sections and thickening along external bends, (backscattered e lectron image) 78 3c : AU52-3-12 shows is lands of o r i g i n a l gold separated by rim gold, (backscattered e lectron image) 78 3d : AU52-4-13 shows is lands of o r i g i n a l gold separated by rim gold , (backscattered e lectron image). 78 Plate 4a : AU52-2-20 shows is lands of o r i g i n a l gold separated by rim gold, (backscattered e lectron image) 80 4b : AU52-4-15 shows lenses of rim gold within a gold p a r t i c l e , (backscattered e lectron image) 80 v i i i L I S T OF FIGURES F i g u r e Page 1 : Sample L o c a t i o n 82 2a : E x p e r i m e n t a l l y D e r i v e d S o l v u s a t V a r i o u s T e m p e r a t u r e s f o r t h e Cu-Ag-Au T e r n a r y 83 2b : R e c o v e r y o f D i f f e r e n t S i z e Au P a r t i c l e s by G r a v i t y D e v i c e s 83 B r a l o r n e B u l l i o n F i n e n e s s 84 P i o n e e r B u l l i o n F i n e n e s s 85 L y t t o n 86 G o l d Pan 92 L i l l o e t t 96 Lower B r i d g e 102 B r i d g e - Y a l a k o m J u n c t i o n 104 Y a l a k o m 110 R e l a y 114 B a s s f o r d 118 L i g h t e n i n g 120 K i n g C u r v e 126 A l h a m b r a 130 851 134 P i o n e e r M i l l 1 38 B r a l o r n e M i l l 142 C a d w a l l a d e r 146 Y a l e 150 Upper B r i d g e 154 S t i r r u p 158 Upper F r a s e r 1 64 B i g Bar 170 F o u n t a i n Bar 176 F o u n t a i n Rim 180 N e l s o n 184 S o v e r e i g n , 1 88 Hope 192 ACKNOWLEDGEMENTS It i s not possible to acknowledge a l l those who made t h i s thesis possible however the following deserve mention; A l l those who supplied samples. The s t a f f at the Science and I n t e r l i b r a r y Loans Devisions of the University of B r i t i s h Columbia's l i b r a r y for t h e i r help in l ocating the reference material. Ed and Duke for t h e i r help with the sample preparation. The Department of Geological Science for the i r encouragement and support. A s p e c i a l thanks to Dr. K. C. McTaggart for acting as thesis advisor. 1 INTRODUCTION PREVIOUS WORK Previous workers have used the composition of natural gold ( i t s fineness or trace element composition) to deduce the source of placer gold and to c l a s s i f y gold lode deposits. Most of this work has been based on emission spectroscopy and bulk assay r e s u l t s . Some work was based on wet chemistry, r e f l e c t e d l i g h t microscopy and atomic absorption spectroscopy. Fisher (1934) and Fisher (1945) showed that the fineness of placer gold in the Morobe f i e l d of New Guinea can be used to characterise the lode sources and that the average fineness of the placer indicates the r e l a t i v e contributions of the sources supplying i t . Smith (1913) showed that placer gold fineness r e f l e c t s the fineness of the source and does not in every example increase with distance of transport as i s commonly asserted. Mertie (1940) developed a model to explain the d i s t r i b u t i o n of gold and i t s fineness in placers that took into account c y c l i c a l erosion and the changes in lodes with depth. A l l these authors, especially Fisher (1950), and many others have t r i e d to c l a s s i f y lode deposits and their variations using fineness. In general the c l a s s i f i c a t i o n s based on fineness are contradictory, a fact that i s not surprising, considering more recent work on the v a r i a b i l i t y of gold compositions (eg. Gay, 1963). Trace element compositions have been used in more sophisticated attempts to characterise the sources. Gay (1963) 2 provides a review of the data and conclusions up to 1963. One of the few firm conclusions he was able to draw was that gold in the oxidized zones of ore bodies i s purer than the lode gold. In the western world r e l a t i v e l y l i t t l e work has been done on trace elements in gold. Warren and Thompson (1944) made one of the e a r l i e s t attempts and Antweiler and Campbell (1977) are among the most recent workers. Valpeter's paper (1970) i s t y p i c a l of the Soviet methodology in attempts to use trace elements and fineness together to characterise placers and their sources. The Soviets t y p i c a l l y use other variables such as morphology (internal and external) in their studies. The papers of F a y z u l l i n (1971) and Davydov (1970) are t y p i c a l . The Soviets have also t r i e d to c l a s s i f y lode deposits using fineness and trace element compositions but the results seem to suffer from the same inconsistencies as the e a r l i e r c l a s s i f i c a t i o n s based on fineness. No major generally accepted conclusions resulted from th i s trace element work. The problem of new gold (gold p r e c i p i t a t e d in the s u r f i c i a l environment) and reworked gold (gold which has been through more than one cycle of erosion and transportation) should be mentioned. In many placer regions the p o s s i b i l i t y of new gold i s demonstrated, then forgotten only to become the source of controversy for a la t e r generation. Uglow and Johnston (1923) give good accounts of the manner in which t h i s problem i s rat i o n a l i s e d . Yablakova and Ryzhov (1972) showed that not only can a f o s s i l placer supply gold to an active placer but that t h i s 3 reworked gold has commonly been altered. This and the p o s s i b i l i t y of new gold severely l i m i t s the v a l i d i t y of statements on distance of transport (Tischenko and Tischenko, 1974; and Tischenko, 1981). The basic conclusions from fineness and trace element work are: 1) Fineness and composition of gold range widely in individual lodes and placers. 2) Both new gold and reworked gold may contribute to placer formation. 3) Gold fineness does not necessarily increase with distance from the source. These three conclusions can be used to characterise sources but only in a generalised way. Only the Soviets have t r i e d to develop and apply these three conclusions to gold exploration in a sytematic way. It i s important to r e a l i s e that a l l studies using the methods c i t e d suffer from one or more of the following d e f i c i e n c i e s : 1) Averaged data are used to draw conclusions for individual members of the average. 2) Contamination is not systematically accounted for. 3) The a n a l y t i c a l method used yie l d s only the average composition of p a r t i c l e s or c o l l e c t i o n s of p a r t i c l e s , and includes inhomogeneities and mineral inclusions. 4) Samples may be necessarily small and unrepresentative. 5) Sample preparation may lead to the a l t e r a t i o n of the composition of the gold. 4 T h e s e d i f f i c u l t i e s were l a r g e l y overcome when t h e e l e c t r o n m i c r o p r o b e came i n t o use b e c a u s e o f i t s a b i l i t y b o t h t o a n a l y s e s m a l l v o l u m e s , q u a n t i t a t i v e l y and n o n - d e s t r u c t i v e l y , and t o g e n e r a l l y a v o i d i n c l u s i o n s . U s i n g t h e m i c r o p r o b e D e s b o r o u g h (1970) was a b l e t o c o n f i r m t h e p r e s e n c e of r i m s o f >980 f i n e n e s s on some p l a c e r g o l d g r a i n s . Berman e t a l . (1978) showed t h a t t h e t o t a l r a n g e o f c o m p o s i t i o n s i n t h e Ag-Au s e r i e s i s f o u n d i n n a t u r e . Naz'mova and S p i r i d o n o v (1979) and von G e h l e n (1983) c o n f i r m e d t h e o b s e r v a t i o n s o f T r e n i n a and S h u m i l o v (1970) on n a t u r a l g o l d amalgams from t h e U k r a i n e . However F o s t e r e t a l . (1978) c o n c l u d e d t h a t t h e amalgam t h e y s t u d i e d f r o m C a l i f o r n i a was f o r m e d when Hg was i n t r o d u c e d i n t o t h e p l a c e r d u r i n g m i n i n g a c t i v i t y . The g o l d s t u d i e d by b o t h T r e n i n a e t a l . and F o s t e r e t a l . had v i s i b l e Hg r i m s . M i c r o p r o b e work s u c h as t h a t o f P o k r o v s i i e t a l . (1979) and N o v g o r o d v a and T s e p i n (1976) have b r o a d e n e d ou r knowledge o f t h e Cu-Au p h a s e s t h a t o c c u r i n n a t u r e . N e s t e r e n k o e t a l . ( 1 9 8 2 ) , D e s b o r o u g h e t a l . (1970) and (1971) and F i t z g e r a l d e t a l . (1967) show how t h e p r o b e can be u s e d to. r e f i n e t h e a p p l i c a t i o n s o f g o l d a n a l y s i s d e v e l o p e d u s i n g o t h e r methods. -5 Phase D i a g r a m s The g e o c h e m i s t r y and c o m p o s i t i o n o f s y n t h e t i c g o l d a l l o y s has been s t u d i e d i n some d e t a i l . K i k u c h i e t a l . (1980) p u b l i s h e d a c a l c u l a t e d Au-Ag-Cu t e r n a r y phase d i a g r a m s and Chang e t a l . (1977) p u b l i s h e d an e x p e r i m e n t a l l y d e r i v e d Au-Ag-Cu phase d i a g r a m . R o l f e and Hume-Rothery (1967) p u b l i s h e d Hg-Ag and Hg-Au p h a s e d i a g r a m s w h i c h show t h a t from 0$C t o 500$C a s i n g l e phase i s f ormed w i t h a s much as 15% Hg. A l l p h a s e d i a g r a m s a r e f o r one a t m o s p h e r e . 6 METHODS SAMPLE COLLECTION Some placer samples were c o l l e c t e d at the locations shown in Table 1 and in Figure 1 by panning and s l u i c i n g , using a 1 metre s l u i c e . Other samples were purchased or received as donations from placer miners or prospectors. Care was taken to ensure that the gold actually came from the location s p e c i f i e d and had not been altered in any way by amalgamation or acid cleaning. Lode samples were c o l l e c t e d at the sit e s or were donated by the museum at the Department of Geology at the University of B r i t i s h Columbia. These samples are small and probably not f u l l y representative. SAMPLE PREPARATION The smallest grain that can be picked and mounted has an intermediate axis of about 0.4 mm. For flattened p a r t i c l e s the small axis was close to the a n a l y t i c a l diameter of the beam but for equant specimens th i s dimension was much larger than the a n a l y t i c a l diameter. These grains were photographed, given a number, and mounted in p l a s t i c with their long axis v e r t i c a l . The p l a s t i c was heated to 135$C for 15 minutes at atmospheric pressure then l e f t to cool for 10 minutes at 29 MPa. The p a r t i c l e s were ground and polished to a microprobe l e v e l of flatness at the approximate position of the plane including the intermediate and short axes This procedure ensured that a similar planar section from each 7 specimen was exposed, thus reducing the p o s s i b i l i t y of errors caused by differences in depth of exposure between grains (important because of the p o s s i b i l i t y of rimming). Some lode samples were mounted, cut and polished as i s normally done for rock specimens in probe work. For others the rock was crushed and v i s i b l e gold picked by hand, then treated as was the placer gold. A l l specimens and standards were coated with approximately 250 nm of carbon (determined by the interference colour on brass) by vacuum evaporation. SAMPLE ANALYSIS Instrument Setup The samples were analysed on an A.R.L. SEMQ microprobe. Specimen current was set at 100 nA on aluminium. The specimen current was chosen as large as possible to reduce the counting time for the minor and trace elements, but s u f f i c i e n t l y small that the vaporization of Hg was avoided. The accelerating pot e n t i a l , 15 kV, was chosen to minimize interference problems between elements. A 200 #m aperture and as small a beam as possible (as seen on benitoite) was used. At the star t of thi s study a review of the l i t e r a t u r e showed that the number and amount of the elements found in natural gold were poorly known at the microprobe l e v e l . A series of test analyses of the 15 elements (As, Pt, Au, Hg, Pb, B i , Ag, Sn, Sb, Te, Fe, Ni, Cu, Zn, Mn) most commonly reported in emission spectroscopy studies of gold was car r i e d out on samples 8 from the Cariboo and Bridge river areas. Au, Ag, Cu and Hg were the only elements that were consistently present. Values for Ni, Fe, Sb were obtained but the amounts were low, and e r r a t i c . They were not considered further. The remaining elements were below the detection l i m i t . Table 2 shows the spectral lines used and table 3 l i s t s standards. Counting time on each background was 10 seconds and on the peak was 20 seconds. The l i n e s and background stepoffs were chosen after analysing a r t i f i c i a l alloys of gold containing about 1% each of the 15 elements to be analysed for, except for Ag. For Ag, pure Ag and Ag-Au a l l o y s were used. For Hg and Cu the background stepoff i s larger for standards than for samples because interference i s not expected from other elements in the standards. For the analysis of samples, a smaller stepoff was chosen to avoid element interference. This procedure was considered permissible because the Hg and Cu values expected in the samples were mostly less than 1 wt%. It appears that t h i s stepoff became a problem only for values greater than about 10% Hg and was not a problem for Cu. A n a l y t i c a l Procedure Spot analysis was done at a point as near as possible to the middle or core of each grain, well away from the rim. The number of core analyses per sample i s given in table 1. Where possible, the rims of rimmed grains were analysed. Very few of the analyses are considered to be either a mixture of rim and core compositions or rims represented as cores or visa-versa as the rims were nearly a l l v i s i b l e in re f l e c t e d l i g h t . 9 The decision to analyse each grain only once was rat i o n a l i s e d as follows. Primary intragrain inhomogeneity was expected to be the norm rather than the exception so that under t h i s assumption a high precision on a single grain would have less value in defining a population than a number of low precision analyses on random grains. If the primary intragrain inhomogenity i s systematic, that i s , the grain i s concentrically zoned, i t was thought that t h i s would be largely disrupted (through removal and distortion) by the time the grain reached a placer. The evidence from the rimmed grains showed that t h i s i s reasonable for a l l but the most angular grains. Therefore analysing a grain once in i t s centre was considered a random representative sampling of the population. For the very angular (undisrupted) grains the sampling i s of the core only. This allows the population to be represented on element-element and element-fineness plots by the d i s t r i b u t i o n of the analysis points. The method was to standardise on each of the standards l i s t e d above and then run an Ag-Au standard a l l o y as a check on the system. The background stepoffs for Hg and Cu were then changed and the standards rerun. Bence-Albee factors generated by Magic IV were used in the data reduction program. Accuracy Some instrumental errors were detected by checking the background counts and the t o t a l weight percent of each sample. The most common error was caused by beam current d r i f t which resulted in a low t o t a l weight percent. This error occurred 1 0 despite a beam normalizing routine in the program. Experience showed that t o t a l s of about 100% +-2% gave the same fineness value before and after restandardizing to correct for the beam d r i f t . Generally d r i f t s larger than t h i s gave unreliable res u l t s , and therefore only values within t h i s tolerance were considered acceptable. This tolerance i s high but no r e a l i s t i c way around th i s problem was found. Beam d r i f t was not found to a f f e c t s i g n i f i c a n t l y the minor elements except where their values were unusually high. The accuracy of the high Hg values i s not considered to be good, because of the small background stepoff and the possible vaporisation of Hg. In the case of high Cu analyses, many of the t o t a l s were inexplicably high. Previous studies have shown that Hg and Cu values would be expected to occur in amounts generally less than 0.1%. From a single analysis, at the conditions outlined above, the detection l i m i t s for these elements are given in table 4. To be consistent the higher l i m i t was chosen as the p r a c t i c a l detection l i m i t . Precision Each grain was analysed once except when inhomogeneities were being checked. No check on the precision of the analyses was done but, the narrow scatter seen in some populations such as AU48, (Stirrup) shows, bearing the instrument checkout procedure in mind, that population separations, to t h i s degree of scatter, are meaningful. This conclusion is considered to be true for a l l the samples. For Hg-rich v a r i e t i e s the precision i s poor, presumably because of the vaporisation of Hg (eg Table 5, 11 samples AU43-3-5 and AU45-1-5). Homogeneity For some specimens duplicate analyses (Table 5) were made on nearly the same spot. Analyses o r i g i n a l l y run in search for rim compositions are also considered as duplicates (Table 6). These analyses show that the grains are generally homogeneous. The v a r i a b i l i t y of the minor elements i s small except when their values are high. The v a r i a b i l i t y of Hg values from a single source can be large. This appears to be common (Ku'znetsov et a l . , 1982). The v a r i a b i l i t y of Cu values from a single source i s large for specimens with high Cu values and appears to be common (Ramdohr, 1969, p. 324). It i s low for low Cu v a r i e t i e s . In general, as expected from the phase diagrams (Figure 2a), Cu values increase with fineness, and high Cu values are limited to gold of high fineness. It should not be concluded from Figure 2a that the gold was formed at a temperature between 200 and 300$C because the diagram i s for 1 atmosphere and the theoretical and empirical phase diagrams do not agree in d e t a i l . The temperature of mounting i s not thought to have s i g n i f i c a n t l y altered the Hg d i s t r i b u t i o n . The fine structure preserved in the rimmed grains with Hg (eg. AU52-2-4) and the preservation of very high Hg values (eg. AU11-2-10) support t h i s conclusion although the homogeneity of the intragrain Hg values might be considered to contradict t h i s . v DATA PREPARATION The data are displayed in terms of 'fineness', 1 2 ((Au/Au+Ag)* 1000), t o g e t h e r w i t h w e i g h t p e r c e n t Cu and w e i g h t p e r c e n t Hg ( F i g u r e s 5 t o 2 9 ) . T h i s i s p r e f e r a b l e t o n o r m a l i z i n g Au, Hg, Ag and Cu t o 100% b e c a u s e f i n e n e s s i s a f a m i l i a r c o n v e n t i o n . No i n f o r m a t i o n i s l o s t by t h i s t r e a t m e n t of t h e d a t a . The r e a d e r s h o u l d be aware t h a t t h e t e r m f i n e n e s s i s u s e d t o r e f e r t o g o l d c o m p o s i t i o n , n o t g r a i n s i z e and t h a t t h e term ' g r a i n ' i s u s e d t o r e f e r t o a s e d i m e n t a r y p a r t i c l e , not t o a u n i t o f w e i g h t f o r g o l d . 1 3 SAMPLE RELIABILITY Does the sample represent the source or lode population? It seems reasonable to assume that a source area supplied gold with a large s ize range to the placers and that the majority of the grains should be expected to be smal l . Therefore a sample made up of small grains should be reasonably representative of the source. Some authors report that there i s a systematic change in composition with grain s ize but others dispute th i s f inding (Gay, 1963; Desborough et a l . , 1970). In r e a l i t y th i s i s not a problem because as Yeend (1975) .showed the larger grains are abraded during transportat ion to produce a large number of smaller grains . The p o s s i b i l i t y of d i f ferent sources having d i f fe rent s ized gold grains cannot be ruled out. It i s important to show that the sample i s representative of i t s average s ize f r a c t i o n . From Figure 2b (Wang and Po l ing , 1983) the recovery i s about 50% for the lower l i m i t and 80% for most of the s izes of placer p a r t i c l e s of the present study. Pure Au has a density of 19.3, Ag of 10.1 and magnetite, (the heavy mineral most commonly associated with gold in placers) a density of 5.2. Most of the gold recovered has a density above 15, s i g n i f i c a n t l y above that of magnetite. The large density di f ference between gold and magnetite suggests that density alone cannot account for the imperfect gold recovery and implies there i s l i k e l y to have been very l i t t l e sor t ing of the various gold types by dens i ty . The other important sor t ing factor i s shape. Small f l a t grains w i l l have the lowest c o l l e c t i o n e f f i c i ency because of the large surface to mass r a t i o compared to small spher ica l grains or large angular gra ins . Because these 14 s m a l l f l a t g r a i n s make up t h e b u l k o f t h e s a m p l e s where t h e shape would become a p r o b l e m , s o r t i n g i s n o t t h o u g h t t o have a f f e c t e d t h e s a m p l i n g r e l i a b i l i t y . T h e r e i s an a d d i t i o n a l s a m p l i n g p r o b l e m . S m a l l e r g r a i n s a r e e x p e c t e d t o t r a v e l f a r t h e r t h a n l a r g e r g r a i n s ( b e c a u s e o f t h e i r l a r g e r s u r f a c e t o mass r a t i o ) so t h a t t h e f a r t h e r a sample i s f r o m t h e s o u r c e t h e s m a l l e r t h e s i z e t h a t r e p r e s e n t s t h e s o u r c e . The s i z e of g r a i n s i n t h e sample t h u s l i m i t s t h e d i s t a n c e from t h e s o u r c e t h a t t h e sample can r e p r e s e n t t h e s o u r c e . As a s m a l l s i z e i s u s e d i n t h e s a m p l e s t a k e n and not a r a n g e i n s i z e s , no f i r m c o n c l u s i o n s c a n be drawn f r o m t h e p r e s e n t d a t a a b o u t t h i s p r o b l e m . B e a r i n g t h e s e a s s u m p t i o n s i n mind i t c a n be c o n c l u d e d t h e s a m p l e s r e p r e s e n t n o t o n l y t h e d e p o s i t s a t t h e l o c a t i o n s f r o m w h i c h t h e y were c o l l e c t e d b u t a l s o t h e s o u r c e s from w h i c h t h e y were d e r i v e d . An a t t e m p t was made t o v e r i f y t h i s by c o m p a r i n g t h e f i n e n e s s d a t a r e p o r t e d by H o l l a n d (1950) w i t h t h e a v e r a g e f i n e n e s s c a l c u l a t e d f o r what were c o n s i d e r e d t o be t h e same l o c a t i o n s , T a b l e 7. The numbers a r e i n t h e r i g h t r a n g e b u t i n c o n c l u s i v e . The a f f e c t of r i m s on t h e a v e r a g e s i s n o t e d b u t t h e r e a r e t o o few d a t a t o w a r r a n t an a t t e m p t t o compensate f o r i t . Many of t h e g o l d g r a i n s a n a l y s e d c o n t a i n Hg. The maximum v a l u e i s c l o s e t o 10%. Most a u t h o r s a s c r i b e i t s p r e s e n c e i n p l a c e r g o l d t o c o n t a m i n a t i o n f r o m t h e a m a l g a m a t i o n p r o c e s s u s e d i n p l a c e r m i n i n g . A few g r a i n s f r o m t h i s s t u d y a r e a show narrow Hg r i m s w h i c h a r e p r o b a b l y t h e r e s u l t of c o n t a m i n a t i o n ( s e e a l s o s e c t i o n on Hg r i m s ) . Naz'mova and S p i r i d o n o v (1979) a r g u e f o r a p r i m a r y o r i g i n f o r Hg i n p l a c e r g o l d and t h e i r v i e w i s s u p p o r t e d 1 5 i n t h i s s t u d y by t h e f o l l o w i n g : G o l d f r o m B r a l o r n e v e i n s , c o l l e c t e d u n d e r g r o u n d , c o n t a i n s up t o 3.96% Hg; one g r a i n o f p l a c e r g o l d (AU52-2-4) h a s an H g - r i c h c o r e a n d a H g - f r e e r i m o f h i g h f i n e n e s s . I f Hg was t h e p r o d u c t o f c o n t a m i n a t i o n , t h e c o n t a m i n a t i o n o c c u r r e d b e f o r e t h e r i m s were f o r m e d . I t c a n be d e m o n s t r a t e d t h a t Hg i s n o t t r a n s f e r e d f r o m Hg r i c h c o n t a m i n a t i o n r i m s t o c o r e s o f n e a r b y g r a i n s d u r i n g t h e p o l i s h i n g p r o c e s s of t h e s a m p l e p r e p a r a t i o n p r o c e d u r e . Two s a m p l e s d e m o n s t r a t e t h i s : G r a i n AU52-2-4 w h i c h h a s an Hg r i c h c o r e h a s an Hg f r e e r i m ( T a b l e 8 ) . P l a c e r g r a i n AU11-2-10 h a s a b o u t 10 w t % Hg. G r a i n s on e i t h e r s i d e o f t h i s g r a i n were a n a l y s e d , AU11-2-10 r e m o v e d , t h e s a m p l e r e p o l i s h e d a n d t h e s e g r a i n s r e a n a l y s e d . The Hg c o n t e n t o f t h e s e g r a i n s d i d n o t c h a n g e . See T a b l e 9. A n o t h e r k i n d of e r r o r c o u l d r e s u l t f r o m t h e a n a l y s i s o f a v e r y s m a l l g r a i n w i t h a t h i n Hg r i m where t h e e x c i t a t i o n v o l u m e e n c r o a c h e s on t h e Hg r i m . T h i s e r r o r a p p e a r s t o be u n i m p o r t a n t b e c a u s e t h e d i s t r i b u t i o n o f g r a i n s w i t h s i g n i f i c a n t Hg i s s y s t e m a t i c a n d i n d e p e n d a n t o f t h e number o f Hg c o n t a m i n a t e d g r a i n s , i n a p a r t i c u l a r s a m p l e . 16 TEXTURE GRAIN SHAPE No detailed size-shape study was attempted but the following observations were made. The samples can be divided into three general types based on the o v e r a l l sample appearence. Smooth, f l a t : AU50, 51, 52, 11, 43, 75, 01 (Plate 1b) Smooth, s l i g h t l y flattened: AU15, 45, 12, 13, 60 Angular, unflattened: AU42, 14, 18, 19, 48, 59, (Plate 1a) The f l a t gold i s thought to have t r a v e l l e d the greatest distance and the angular gold the least distance af t e r being released from i t s lode source. Yeend's work (1975) may modify t h i s conclusion s l i g h t l y . It i s important to note that the flatness need not always mean distance from source because of the p o s s i b i l i t y , especially with f l a t grains, that they could have been eroded from intermediate c o l l e c t o r s which were formed when the drainage pattern was d i f f e r e n t . Flatness i s a more r e l i a b l e function of the energy expended on the grain during transport than distance of transport. Soviet geologists (e.g. F a y z u l l i n and Turchinova, 1972) have introduced the name "intermediate c o l l e c t o r s " to apply to temporary resting places for gold deposited in the s u r f i c i a l environment. For example, in p r e g l a c i a l times, drainage patterns were at least l o c a l l y d i f f e r e n t from those of the present so that gold could have been supplied from one di r e c t i o n to a gravel deposit but in modern times eroded from i t and transported in a second, perhaps opposite, d i r e c t i o n . S i m i l a r l y , during g l a c i a l times gold was 1 7 c a r r i e d by ice far from it's source and modern streams have been reconcentrating t h i s gold from g l a c i a l d r i f t . The gravel and g l a c i a l d r i f t in these examples would be referred to as intermediate c o l l e c t o r s . The following three generalizations can be made: 1) A l l the f l a t gold i s found in the Fraser r i v e r . 2) A l l the lower Bridge and AU15, (Relay) samples are s l i g h t l y flattened. 3) Samples thought to be near the source (except AU15, (Relay) and AU43, (Yale)) are angular. 4) None of the Cariboo samples i s f l a t . . In general these data are interpreted to mean that the gold in the Fraser has probably had a longer history in the s u r f i c i a l environment than the other samples. Longer history could mean either distance from lode or erosion from an intermediate c o l l e c t o r . The fact that the Fraser gold is obviously f l a t t e r than the other gold at least indicates more 'working'. The gold in the Bridge River,is thought to have a much simpler history than that in the Fraser River. INCLUSIONS AND STAINING Inclusions and staining were seen on some grains. Occasional large inclusions (primary?) were seen in the angular grains. The flattened grains, p a r t i c u l a r l y AU52, (Fountain Bar) commomly have numerous small inclusions, generally around the edge. It i s thought that these were incorporated into the gold grains during transportation. Occasional large inclusions were seen in the flattened grains. In general the flattened grains 18 were d i r t i e r looking than the angular grains. Oxide staining was seen on some of the more angular samples. It appears to be a p r e c i p i t a t e deposited on the gold in the placer. Its significance i s unknown. RIMS Rim i s the word used in the l i t e r a t u r e to refer to the outer zone of a concentrically zoned gold grain. This convention i s maintained in t h i s study. Rims, described by Desborough (1970), were observed only in the samples from area 3. In re f l e c t e d l i g h t (on the carbon coated prepared polished samples) rims are l i g h t blue in contrast to the dark blue of the cores. The rim most d i f f i c u l t to see i s either a very thin one or one in which the change in composition between core and rim is small. The backscattered electron photographs provide finer d e t a i l than the re f l e c t e d l i g h t images and show that the few low fineness values (<970) for rims are probably due to the analysis of two phases (Plate 2a). Only a few grains show complete rims. Some grains have li g h t e r areas in embayments, along cracks and in folds. These are interpreted as preserved rim remnants. Rim analyses of AU52 grains, AU52R (Fountain Rim), appear to be t y p i c a l and are given in figure 26. Rim core pairs of analyses are given in table 8. Analyses show that: 1) the rims are Au-Ag a l l o y s with no Cu and no Hg, -2) rims f a l l in the fineness range 970-992 (ignoring two rims), with a mean fineness of 985.9; and 3) rim composition is independent of the i n i t i a l core 19 composition. Note esp e c i a l l y AU52-2-4,. AU52-2-23 (Table 8) which show Hg-rich cores with Hg-poor rims. Desborough (1970) gives three possible origins of rimming: 1) Formed during the primary (lode) deposition of the gold; 2) Formed by the addition of gold and s i l v e r in the s u r f i c i a l environment; and 3) Formed by the removal of s i l v e r and copper (this writer would include Hg) in the s u r f i c i a l environment. Although some lode gold i s inhomogeneous, i t i s d i f f i c u l t to see why primary inhomogeneities would appear so frequently as rims on d e t r i t a l grains. One would expect grains with randomly oriented boundaries between phases. The rimming seen is therefore not considered to be primary. The debate over addition of Au and Ag versus the removal of Ag i s an old one. Desborough (1970) favours removal of Ag and evidence from the present study supports t h i s view: 1) " In a l l cases the high Ag - low Ag contact i s sharp. Along i t s length the contact i s smooth or wavelike with the cusps either towards or away from the contact. In these examples, simple addition of a rim to a core i s not reasonable because the core does not have the shape of a placer p a r t i c l e . The contact resembles a 'reaction front'. See examples AU52-3-6, AU52-2-9, AU52-5-15 (plates 2a, 2b, 2c). Because the Au-Ag system shows complete s o l i d solution with no phase reactions, removal of Ag by d i f f u s i o n from a grain of arbita r y Au-Ag composition would be expected to produce a gradational interface between the Ag-rich and Ag-poor portions 20 of the grain. Data presented by Desborough, (1980) shows that the boundary i s sharp and between 4#m and I0#m wide, (depending on the core composition). He concluded that the boundary must have formed at <100$C because the d i f f u s i o n rate at 300$C is too large for such a sharp boundary to be preserved. The sharpness of the boundary could explained i f the d i f f u s i o n rates of Ag through the rim were s i g n i f i c a n t l y faster than through the primary grain. This might be the case i f the loss of Ag were due to d i f f u s i o n through a rim-zone crowded with defects due to previous . leaching, of the a l l o y . The interface would thus represent a contact between a defect-riddled rim with a high d i f f u s i o n c o e f f i c i e n t and a well-annealed primary core with few defects and a low d i f f u s i o n c o e f f i c i e n t . If t h i s process can be v e r i f i e d or understood there is the p o s s i b i l i t y that the time needed for rim formation could be calculated and placer reworking h i s t o r i e s deduced. 2) AU52-1-18 and AU52-1-21 (Plates 2d and 3a) show formation of high fineness gold along cracks. Although i t i s obvious that the fine gold in some of the cracks i s the result of folding of rimmed gold grains, for most grains, which are unfolded, i t i s d i f f i c u l t to imagine a process by which gold i s deposited along cracks. 3) The uniform thinness of the rims along straight sections and the thickness at sharp external bends in p a r t i c u l a r support the removal of Ag model, for example AU52-4-26 (plate 3b). 4) Islands of the o r i g i n a l gold are separated from each other by r e l a t i v e l y large distances in some grains, such as AU52-3-12, AU52-4-13, AU52-2-20 (plates 3c, 3d, 4a). This 21 configuration would be d i f f i c u l t to achieve by deposition. Backscattered electron images reveal lenses of gold of rim composition within some gold p a r t i c l e s , such as AU52-4-15 (plate 4b). These lenses may be explained by a l t e r a t i o n along defects in the gold p a r t i c l e or by the compaction of a p a r t i c l e such as AU52-1-18 (plate 2d) after rimming. Rimming by removal of Ag or other elements takes place in the environment of oxidation around an orebody or in intermediate c o l l e c t o r where water composition and conditions are favourable. As rimmed gold is found only in the Fraser rive r i t i s thought that" rimming took place in an intermediate c o l l e c t o r near the Fraser or was rimmed at the lode or at a more distant intermediate c o l l e c t o r and transported to i t s present location. In any event no rimming s i t e i s presently known in the Bridge river area presumably because of g l a c i a l scouring. Because of the state of preservation of the rims both of the transported rimmed gold hypotheses are considered unlikely for a l l but the thickest rims, or the shortest distances of transport. Obvious candidates for rimming s i t e s along the Fraser r i v e r are .the outwash gravels (compare with the description of intermediate c o l l e c t o r s given by Yushmanov (1972)) or an e a r l i e r Fraser r i v e r placer, such as described by Lay (1940). The data in table 10 were c o l l e c t e d using r e f l e c t e d l i g h t in order to provide more information about the rims and therefore, i n d i r e c t l y , information about the rim forming intermediate c o l l e c t e r s . Although gold does not become rimmed only in intermediate c o l l e c t o r s , t h i s i s generally the case 22 (Desborough, 1971; Yablakova, 1972; Z a r i t s k i i , 1980;). The l i m i t i n g factor appears to be time. Thus the percentage of the t o t a l number of grains which are rimmed i s interpreted to mean the percentage of grains from an intermediate c o l l e c t o r . The percentage of rimmed grains in which more than 20 percent of the rim i s preserved (as seen in polished section under the microscope) i s interpreted to indicate the nearness to the intermediate c o l l e c t o r . The further the rimmed grains have t r a v e l l e d from the intermediate c o l l e c t o r the more the rim i s disrupted, and the fewer the grains that w i l l have well preserved rims. From the few backscattered electron images i t appears that the number with well-preserved rims i s s l i g h t l y underestimated (Table 10). It also appears from the backscattered data that there are two types of rims, a very thin rim which cannot have t r a v e l l e d far without being disrupted and a thick rim. A placer deposit whose grains have been completely altered by the rimming process w i l l show fineness of 970-1000 as Z a r i t s k i i (1980) has pointed out. The p o s s i b i l i t y of completely altered grains i s important in discussions on the fineness of f o s s i l placers, in p a r t i c u l a r Archean placers. The percentage of the t o t a l number of grains that are more than 20 percent rimmed i s interpreted to indicate the influence of a nearby intermediate c o l l e c t o r s on supplying gold to the sample. The greater the number of grains more than 20 percent rimmed the greater the contribution from the nearby intermediate c o l l e c t o r . If a placer i s formed by erosion of an intermediate c o l l e c t o r only, a l l the grains (except for those grains whose 23 rims are completely removed during transport or which are t o t a l l y altered) would be rimmed. If a placer i s formed from a primary (lode) source which has supplied an intermediate c o l l e c t o r which is also now acting as a source, a much higher percentage of the grains would be unrimmed. If no rimmed grains are present, the placer was formed from a primary source or an intermediate c o l l e c t o r in which no rimming has taken place. Grain shape may provide a c r i t e r i o n to destinguish between these two sources. It is possible for gold to be mobilized and precipitated in the s u r f i c i a l environment remote from the o r i g i n a l source of the gold. This i s c a l l e d new gold. The c r i t e r i a presently used for id e n t i f y i n g new gold is dependant on a combination of location, association and form of the gold and do not depend on composition, (although the gold i s inferred to be pure). Although the role of new gold w i l l not be considered further in th i s compositional study i t may play a role in the o r i g i n of placer gold of unknown source. The evidence (Warren, 1979) for c a l l i n g the gold from AU48 new gold i s ambiguous. Crystal faces do not necessarily indicate new gold (Petrovskaya, 1971) and although new gold i s argued to be of a high fineness, the importance of Hg and Cu in new gold is unknown. In addition the presence of B i , Te; B i , Te, S; Pb, S (galena); and Cu, S, Sb minerals ( i d e n t i f i e d using the Scanning Electron Microscope), and the presence of numerous vugs in the gold indicate that t h i s gold has a shallow depth (epithermal) lode o r i g i n . The often reported increase of fineness with transport 24 distance (eg. Colin, 1946) i s thought by this writer to r e f l e c t the change in fineness caused by rimming, as rim thickness increases with time (distance). The f l u v i a l system studied i s too complex to r e f l e c t t h i s change in fineness with distance. The work of Koshman and Yugay (1972) provides a good overview of the possible causes of fineness v a r i a t i o n in placers. Hg Rims Hg rims were seen most commonly in specimens from the Fraser r i v e r . They are ea s i l y seen as they give the grains a s i l v e r y appearance, but in polished section (carbon coated) they are less evident and are obviously very t h i n . In polished section they are dark blue, commonly with an embayed outer margin. Extremely Hg-rich grains are porous (spongy). Grains rimmed by Hg were generally not mounted or analysed. 25 DISCUSSION The following features can be used to assign the samples to one of these areas. Area 1-Cariboo: Low Cu and Hg; wide va r i a t i o n in fineness. Area 2-Bridge River: High Hg and Cu populations; fineness somewhat r e s t r i c t e d . Area 3-Fraser River: Some high Cu, some high Hg; fineness has a continuous spread from 600-1000. High percentage of rimmed grains, high percentage of flattened grains. GOLD GROUPINGS It was hoped that in a l l samples i t would be possible, on compositional grounds, to define populations which r e f l e c t the ori g i n of the gold. The proportions of the populations would suggest the r e l a t i v e importance of each source, and the shape, size, rimming and inclusions would aid in the source interpretation and modification history. In theory t h i s should be done s t r i c t l y on s t a t i s t i c a l grounds using a technique such as cluster analysis or pr o b a b i l i t y plots but, because of the small number of data points for each sample and the v a r i a b i l i t y in the data d i s t r i b u t i o n between samples, i t was concluded that these methods would not improve on the empirical observations. Preliminary t e s t s , using p r o b a b i l i t y plots, support this conclusion. In addition, attempts to seperate poorly defined or overlapping populations would probably not be meaningful because, at the expected l e v e l of confidence with which this could be done, i t would not be possible to eliminate the 2 6 geologically reasonable interpretation that these data, for t h i s study, form a single population. In practice the separation has been done by inspection with consideration given to the s t a t i s t i c a l and geological l i m i t s applicable to each sample. As mentioned before high Hg and Cu gold and their sources are observed to have a larger varia t i o n than populations where these values are low. It i s also expected that the closer the sample i s to the o r i g i n a l source of the gold the more r e s t r i c t e d the d i s t r i b u t i o n of those population members would become. INTRODUCTION In the following discussion of placer gold and i t s origins i t is assumed that gold from Bridge River lodes has t r a v e l l e d down Bridge River to the Fraser River and that Cariboo lodes and placers have also contributed gold to placers in the Fraser River. It i s also assumed that l o c a l sources (lodes, f o s s i l placers, etc) have added to the complexity of placer composition at any point in the watershed. It i s d i f f i c u l t in downstream placers which have been modified by downstream additions, such as those of the lower Fraser River, to d i s t i n g u i s h individual contributions from distant headwaters. Ideally, for studies l i k e t h i s one, placer gold samples from the lower parts of r i v e r systems should consist of many more grains of gold than those c o l l e c t e d from their headwaters because contributions from many sources must be distinguished in downstream samples; such thorough sampling has not been possible in t h i s study. In addition contributions from 27 t r i b u t a r i e s could be revealed by more clos e l y spaced samples. A d i s t i n c t i o n i s made in this model between source gold and downstream gold. Source gold includes lode gold and placer gold occurring highest in the Fraser River drainage system. Downstream placers are assumed to be fed not only from the up-stream sources but also from nearby lodes and gold derived from them by weathering and erosion. In source sample plots i t i s commonly possible to determine concentrations or clusters (AU33, 34, 37, (Bralorne lodes), figures 14, 15, and 16), or well delimited zones of r e s t r i c t e d fineness and large Hg spread (plumes) (AU14a, (Yalakom placer), figure 10). These concentrations or zones within a sample are referred to here as populations. In downstream placers, such populations are less well defined because of mixing and d i l u t i o n . In some plots, such as AUO1, (Lytton), (fineness vs Hg plot) the pattern appears to be nearly random, with, in t h i s example, a single weak population near fineness 1000. In "downstream" placer samples one can test for the presence of a p a r t i c u l a r "source" gold, using the assumption, for example, that Cariboo gold population has a fineness of 715-960, Hg less than 0.05% and Cu up to 0.1% at high finenesses. On t h i s assumption, AU01,(Lytton) (r e f e r r i n g to the fineness-Hg plot, figure 5), could be said to have a population of 14 grains of Cariboo gold although these 14 grains do not form a concentrated r e s t r i c t e d population. But, since Bralorne gold shows a population fineness of 720-900, with Hg values up to 4%, some Hg free grains assigned to the Cariboo population could equally well be assigned to a Bralorne population. Rimming provides 28 another basis for discerning populations. About one t h i r d of the placer grains from Fraser River are rimmed with gold of high fineness so that for each sample two populations can be distinquished (see table 1 0 ) . Yalakom AU14a and Relay AU15a are examples of populations which have a large spread in Hg values over a r e s t r i c t e d fineness spread. These populations, or plumes, could represent contributions from many di f f e r e n t deposits but i t i s also possible that each plume shows the v a r i a b i l i t y of composition of a single deposit, a single vein or even a part of vein. Examples of such v a r i a b i l i t y within lodes are common: AU33 (Bralorne vein), 4 grains, shows a wide range of Hg values. Kusnetsov et a l . (1982) report that "Native gold from some regions of the Ukraine contains Hg 1-6% .... Microprobe analysis showed that the Hg was rarely evenly d i s t r i b u t e d in the gold grains The Hg and Au c r y s t a l l i z e d simultaneously". Novgoroda and Tsepin (1976) describe gold from the southern Urals which i s a mixture of several v a r i e t i e s , including copper-rich (up to 46%), s i l v e r -r i c h (up to 49%) and mercury-rich (up to 9%), a l l of which may be intergrown in a single aggregate. AREA 1 (CARIBOO) Samples Lode A single specimen from the Cariboo Gold Quartz mine (AU17) has a fineness of 955.6 and neither Hg nor Cu, see table 11. 29 Placer AU18 (19 grains), AU19 (43 grains), AU59 (20 grains) and AU60 (20 grains) have a fineness range from 710-960, absence of Hg, except in AU60 (3 grains), and presence of detectable Cu (up to 0.25%), mainly in gold of fineness greater than 900. The samples are small (figures 12, 13, 27, 28). Interpretation The samples are small and cannot be said to be representative of the area. AREA 2 (BRIDGE RIVER) Source Samples Lode samples Bralorne Area: Samples from the Bralorne mine incude: 1) A suite of vein samples: AU21,AU22 and AU25 (single specimens), (Table 11). AU22 has an unusual composition of 1.08% Cu and a fineness of 966. The location of these samples within the Bridge River camp i s not exactly known. AU33, AU34 and AU37, 4,7, and 8 grain samples extracted from three d i f f e r e n t veins on the 500-level (figures 14, 15, 16). These three samples have d i s t i n c t populations: AU33, 30 fineness 780-820", up to 4% Hg; AU34, fineness 800-840, 0.2-0.3% Hg; and AU37, fineness 760-835, up to 0.1% Hg. 2) Bralorne m i l l findings (AU40) which, i t i s believed, represent late production from deep parts of the mine, agree clos e l y in fineness (850) with 1961-72 production (figure 3). AU40, fineness 800-890, shows a "plume" of Hg values to 4.55% (figure 18). Placer Samples Relay Creek (AU15) ; (40 grains; figure 11) i s characterized by two populations: AU15a (10 grains): Fineness 900-1000, Cu 1.2-22.6% and Hg to 0.3%. AU15b (24 grains): Hg plume, fineness 760-890 Hg to 2.08%, <D.L. (detection l i m i t ) Cu. Yalakom River (AU14) ; (45 grains; figure 10) AU14a (29 grains): Fineness 760-835 with an Hg plume r i s i n g from 0.4 to 6.5%, Cu up to 0.1%. AU14b (11 grains): Fineness 860-910, up to 0.1% Hg and up to 0.1% Cu. Stirr u p Creek, (AU48) ; (54 grains; figure 22) AU48a (47 grains): Fineness 910-960, up to about 1% Hg and about 0.3% Cu. AU48b (5 grains): Fineness 880-920, 1.8-3% Hg, up to 0.1% Cu. (Possibly AU48a and b are part of the same population). 31 Downstream Placer Samples Cadwallader , (AU42) ;(70 grains; figure 19) AU42a (48 grains): Fineness: 780-900, up to 0.3% Hg, <D.L. Cu. AU42b A broad, weak concentration at fineness 720-810, up to 0.6% Hg. Upper Bridge (AU45) ;(87 grains; figure 21) AU45a (11 grains): Fineness 910-1000, Cu 2%-16.5%, Hg to 0.08%. AU45b (14 grains): Fineness 760-870, up to 0.3% Hg, <D.L. Cu. AU45c (7 grains): Fineness 830-885, up to 0.15% Cu, up to 0.15% Hg. AU45d (11 grains): Fineness 928-970, up to 0.25% Cu, up to 1% Hg. AU45e (68 grains): Hg plume, fineness 760-970, up to 4.89% Hg, high gold side of plume i s r e l a t i v e l y Cu-rich Bridge-Yalakom Junction (AU13) ;(34 grains; figure 9) AUl3a (10 grains): Fineness 960-1000, Cu 2.24%-23.9%, Hg to 0.1%. AU13b (4 grains): Fineness 890-940, up to 0.15% Hg, up to 0.15% Cu. AU13C (7 grains): Fineness 780-870, 0.2-1.5% Hg, Cu up to 0.13%. AU13d (15 grains): Fineness 760-860, Hg plume r i s i n g to 1.5% Hg, <D.L. Cu. Lower Bridge (AU12) ;(69 grains; figure 8) 32 AU12a (11 grains): Fineness 910-1000, up to 31% Cu, up to 0.17% Hg AU12b (21 grains): Fineness 780-840, up to 0.3% Hg, up to 0.13% Cu. AU12c (25 grains): Hg plume, fineness 780-880, to 3% Hg, Cu <D.L.. AU12d (6 grains): Hg plume fineness 880-1000, with up to 0.4% Cu, up to 1.4% Hg. Interpretation Introduction Three sources, Bridge River lodes and Relay Creek and Yalakom River placers, provide samples near the headwaters of the Bridge River watershed. The lodes from which the second and th i r d sources were derived are unknown. The compositional populations are d i s t i n c t for a l l three. Tentatively the conventional view i s adopted that gold from these three (and other unknown) sources has been c a r r i e d downstream to contribute to the four downstream placers that have been sampled. Correlation of populations between placers i s far from perfect. Some differences would probably be resolved by more extensive sampling. Some d i f f i c u l t i e s are due to the vagaries of sedimentation - nothing is known of the stratigraphy of the 33 deposits. New concentrations appearing downstream may represent new sources. Where populations disappear downstream, they may have been d i l u t e d beyond recognition by other gold, or may be derived from recently uncovered veins whose gold has not yet reached the downstream s i t e . The concept of continuous travel of gold in the present downstream d i r e c t i o n i s overly simple. Although the importance of intermediate c o l l e c t o r s , such as g l a c i a l d r i f t and gravels, in the Bridge River drainage has not been assessed, there i s no doubt that some of the d i f f i c u l t i e s of trying to correlate gold populations between placers are due to the contributions from intermediate c o l l e c t o r s and the e f f e c t of the associated changes in dispersal patterns. Topographic maps show that Bridge River between Marshall Creek and Gun Creek (some 25 km), meandered over a f l a t up to 2 km wide before i t was flooded for a power project. It i s doubtful that such a r i v e r would be capable of transporting gold, yet Bralorne gold i s tentatively i d e n t i f i e d in t h i s study, at Bridge-Yalakom Junction and Lower Bridge. Was t h i s gold transported in a swift p r e - g l a c i a l Bridge River whose high gradient has been lowered by f a u l t i n g with recent a c t i v i t y near Carpenter dam (map 13-1973, Roddick and Hutchison, 1973), or was Bralorne gold c a r r i e d north and east by ice, later to be washed out of d r i f t and concentrated in lower Bridge River? A l t e r n a t i v e l y , the gold i d e n t i f i e d as coming from Bralorne could have come from a d i f f e r e n t source. It i s apparent that detecting and c o r r e l a t i n g gold populations from d i f f e r e n t placer deposits i s subjective, and 34 two observers may not agree. Cadwallader (AU42) AU42a seem to have been derived largely from the Bridge River lodes (AU21, 25, 33, 34 and 37) - agreeing in range of fineness, range of Hg values, and absence of Cu. Early production records show a fineness of about 740-820, possibly seen as AU42b. Two high Hg values (about fineness 840) in AU42 could represent AU33 (vein) and AU40 (mill f i n d i n g s ) . Upper Bridge (AU45) The high copper population (AU45a) could be derived from Relay Creek (AU15a). An alternative view may be taken that, as high-copper gold occurs t y p i c a l l y in ultrabasic rocks, and as the Bridge River drainage area includes many areas of such rocks, i t i s quite possible that the high copper gold of the Bridge River placers i s derived from many such sources and i s not necessarily related to the Relay Creek source. AU45b may have been supplied by the Relay (AUl5b) or by the Bralorne lodes (the l a t t e r via Cadwallader (AU42a)). AU45c and AU45d cannot be related to any known am lodes or placers. AU45e may include Relay AUl5b but includes a copper-rich zone on the high fineness side of the Hg plume (cf. AU12d). It is noteworthy that AU45e, has a broad Hg plume that i s not v i s i b l e in Cadwallader (AU70),possibly indicating a high Hg source similar 35 to that supplying AU14a. Bridge-Yalakom Junction (AU13) AUl3a i s tentatively correlated with Relay AU15a but AU13a shows a narrower range of fineness than AU15a. AU13b may be related to Yalakom, AU14b, being s i m i l a r , but not i d e n t i c a l in fineness, Hg and Cu. AU13c may include some Bralorne and 2 grains (measurable Cu, low Hg) could be from AU45c (Upper Bridge). AUl3d is a Hg "plume" that may be a mixture of Relay (AUl5b) and Bralorne AU40 and AU33. That Bridge-Yalakom Junction contains a higher r a t i o of high copper values to low Cu values than does Relay (AU15) and a more r e s t r i c t e d fineness range, weakens the argument for deriving the one from the other. The sample, however, contains only 34 grains. This might also explain the difference in plume fineness range between AU13d and AU45e. Lower Bridge (AU12) AU12a resembles Relay (AUl5a), Bridge-Yalakom Junction (AU13a) and Upper Bridge AU45a. Seventeen grains (low Cu) of AU12b ( t o t a l 24 grains) could be derived from Bralorne. They may form the base of a Hg plume AU12C. AU12d (Hg plume with measurable Cu values) resembles Upper Bridge AU45e. AU12 o v e r a l l very c l o s e l y resembles Upper Bridge (AU45), with AU45c removed. AU12b forms an unusually well defined population, not obvious at 36 Bridge-Yalakom Junction (AU13) but apparently present at Upper Bridge (AU45) and Cadwallader (AU42). Gold for which no source can be suggested includes Upper Bridge AU45c, 45d and the pair AU45e and Lower Bridge AU12d, the subsidiary plume formed by high Hg, r e l a t i v e l y high Cu values on the high fineness side of a Hg plume. AREA 3 (FRASER RIVER) Downstream Placer Samples  Upper Fraser (AU50) ;(94 grains; figure 23) AU50a (39 grains): Rimmed, fineness 690-880, Hg to 0.9%, <D.L. Cu. AU50b (55 grains): Unrimmed, fineness 700-1000, Hg to 4.86%, Cu to 0.1% above fineness 880, 4 grains showing moderate to high Cu. AU50c (6 grains): Fineness 600-650, variable Hg, belong to a group found only along Fraser River (cf. AU51C), and includes both rimmed and unrimmed grains. AU50d (3 grains): Fineness 960-1000, with Cu ranging up to 11.68%, no Hg. Big Bar (AU51) ;(39 grains; figure 24) AU51a (11 grains): Rimmed, fineness 720-920, Hg to 0.6%, may be two populations. AU51b (28 grains): Unrimmed, fineness 750-990, Hg to 0.4%. AU51C (3 grains): Fineness 610-640 AU51d (18 grains): Fineness 950-1000, <D.L. Cu, Hg to 0.5%. Rim compositions, (see Figure 26). 37 Fountain Bar (AU52) ;(144 grains; figure 25) AU52a (53 grains): Rimmed, fineness 720-940, Hg plume-like, to 6.38% Hg, Cu mostly <D.L.. AU52b (27 grains): Unrimmed, fineness 770-1000, Hg to 1.5% and not forming a well-defined plume, Cu mostly below 0.1%. AU52c (43 grains): Fineness 715-960, Hg <D.L., Cu detectable at high fineness. Would overlap with AU52a and AU52b. AU52d (11 grains): Unrimmed, fineness about 600-670, Hg to 5. 35%, Cu <D.L.. L i l l o o e t (AU11) ;(62 grains; figure 7) AU11a (6 grains): Fineness 980-1000, up to 24% Cu, <D.L. Hg. AU11b (25 grains): Unrimmed (excluding high copper grains), fineness 700-900, Hg plume (?) to 2.36% Hg, Cu <D.L., (to 0.1% at high fineness values). AU11c (18 grains): Rimmed, fineness 730-860, Hg to 0.9%, Cu <D.L.. AU11d (6 grains): Fineness about 600-670, variable Hg, <D.L. Cu. Lytton (AU01) ; (-7 3 grains; figure 5) AU01a (22 grains): Rimmed, fineness 760-880, Hg to 1.63%, Cu mostly <D.L.. AU01b (41 grains): Unrimmed, fineness 800-1000, Hg to 1.3%, Cu to 0.9%. AUOlb' (17 grains): Unrimmed, fineness 850-1000, Cu 0.05-0.9%, Hg mostly <D.L., but ranging to 1.26%. AU01 c (6 grains): Fineness 600-J550, range of Hg, <D.L. Cu. Yale (AU43) ;(75 grains; figure 20) Some 5 grains show 38 rimming. AU43a (39 grains): Fineness 770-900, Hg to 0.4%, Cu <D.L. AU43a' (50 grains): Fineness 770-900, Hg "plume" to 2.42%, Cu <D.L.. AU43b (2 grains): Fineness 980-1000, Cu 6% and 22%, Hg <D.L.. AU43d (3 grains): Fineness less than 660, Hg to 5.8%. Hope (AU75) ,-(58 grains; figure 29) AU75a (15 grains): Rimmed grains, fineness 720-890, Hg to 0.7%, Cu near <D.L.. AU75b (45 grains): Unrimmed, fineness 695-1000, Hg to 1.2%, Cu <D.L., r i s i n g above fineness 850 to 0.18%. AU75c (2 grains): Fineness 660 Interpretation In general, concentrations of values on fineness-Hg plots are fewer and the range of fineness larger in Fraser River samples than in Bridge River samples. This dispersion i s probably due to mixing of gold from many dif f e r e n t sources. A l l Fraser River samples include rimmed and unrimmed gold in various proportions (see table 10). On the average about 37% of the grains are rimmed. In the following discussion i t i s assumed that rims formed on d e t r i t a l grains of gold in s u r f i c i a l deposits (intermediate c o l l e c t o r s such as s o i l s and gravels) by pre f e r e n t i a l leaching of s i l v e r by groundwater. This process i s thought to be slow. Eventually the c o l l e c t o r was eroded, and the now rimmed gold mobilized, f i n a l l y coming to rest in the present 39 Fraser River placers, mixed with unrimmed, probably recently eroded gold. Where was the intermediate c o l l e c t o r in which the rims formed? One p o s s i b i l i t y i s Tertiary or older conglomerates such as those in Fraser River near Quesnel (Lay, 1940), upstream from a l l Fraser River samples. If i t were assumed that a l l of the rimmed gold comes from Quesnel, the o r i g i n a l source unknown, the proportion of rimmed grains should decrease and that of badly worn rims should increase regularly downstream however both seem to change e r r a t i c a l l y , suggesting the existence of several intermediate c o l l e c t o r s . A second possible intermediate c o l l e c t o r i s p r e - g l a c i a l gravel near Cariboo lodes. It i s possible that after rimming had taken place, rimmed gold found i t s way down the Cariboo and Quesnel r i v e r s to Fraser River placers. This hypothesis could account for some 22% of the rimmed gold on the assumption that Cariboo samples (AU18, 19, 59 and 60) represent the source. For the same reason as that given for the f i r s t possible intermediate c o l l e c t o r t h i s percentage must be considered a maximum. Note that when reference i s made to the composition of rimmed gold, the reference i s to the core of the grain, not to the rim. A t h i r d p o s s i b i l i t y i s that the gold became rimmed while in p r e - g l a c i a l regoliths near the Bridge River lodes. Bridge River gold could have been transported to s i t e s on upper Fraser River (eg. Upper Fraser) in a Tertiary drainage system (cf. Lay, 1940) that drained northerly, or by g l a c i a t i o n , the d i r e c t i o n of ice t r a v e l being northeasterly. The distance that this gold would 40 have had to travel suggests that the rims would have been e n t i r e l y removed, making this suggestion less a t t r a c t i v e , but i t should be remembered that no data are available on rim growth or removal. The problem with a l l these possible rim forming intermediate c o l l e c t o r s is that they require that the rimmed gold be transported long distances to i t s present location with l i t t l e disruption to the rim. It seems more reasonable to assume that gold was transported prior to the formation of the rim and that the rim forming intermediate c o l l e c t o r was close to the present placer location. The observed v a r i a t i o n of rim percentage and rim content (Table 10) supports t h i s idea. Much of the g l a c i a l outwash and other suitable sedimentary rocks along the Fraser River can therefore be considered as possible rim forming intermediate c o l l e c t o r s . Although unrimmed gold has a higher average fineness than rimmed gold in a l l samples, there i s considerable overlap in composition so that rimmed and unrimmed gold of the same composition occurs in the same sample. These observations suggest that certain lodes may have supplied gold to placers over a long period of time. Possibly the lodes were v e r t i c a l l y zoned with respect to fineness of gold, the difference in fineness being related to shallow derivation of old gold but deeper derivation of young gold. The t o t a l unrimmed population shows a concentration of compositions with fineness greater than 900 which i s absent in the rimmed population - a range that includes most of the Cariboo gold (AU18, 19, 59 and 60). In addition, most of this 41 c o n c e n t r a t i o n o c c u r s i n t h e unrimmed g o l d from F r a s e r R i v e r u p s t r e a m f r o m t h e mouth o f t h e B r i d g e R i v e r . The r e a d e r i s r e f e r r e d t o t h e s e c t i o n on rimming and t a b l e 10 f o r f u r t h e r i n f o r m a t i o n on t h e s i g n i f i c a n c e of r i m f o r m i n g s o u r c e s i n t h e f o r m a t i o n of t h e F r a s e r R i v e r p l a c e r s a m p l e s . The p r o p o r t i o n of g o l d t h a t c o u l d be a s s i g n e d a C a r i b o o o r i g i n d i m i n i s h e s s l i g h t l y f r o m t h e Upper F r a s e r sample s i t e t o F o u n t a i n B a r , i s r e d u c e d m a r k e d l y a t L i l l o o e t (due t o d i l u t i o n by B r i d g e R i v e r g o l d ? ) , m a i n t a i n s t h i s r e d u c e d l e v e l t o Y a l e , and u n e x p e c t e d l y r i s e s s i g n i f i c a n t l y a t Hope. A l l F r a s e r R i v e r samples c o n t a i n g o l d of f i n e n e s s n e a r 600, w i d e l y r a n g i n g Hg v a l u e s , rimmed and unrimmed, and t h e s e s c a t t e r e d g r a i n s may be f r o m a s i n g l e s o u r c e d i s p e r s e d downstream b u t seems more l i k e l y t o r e p r e s e n t d i f f e r e n t s o u r c e s of t h e same t y p e b e c a u s e t h e number of g r a i n s r e m a i n s c o n s t a n t o v e r a l o n g d i s t a n c e . B e c a u s e o f t h e wide r a n g e o f c o m p o s i t i o n s of F r a s e r R i v e r g o l d , rimmed and unrimmed, t h e s c a r c i t y o f c o n c e n t r a t i o n s i n f i n e n e s s - H g - C u p l o t s , and t h e l a c k of i n f o r m a t i o n a b o u t p o s s i b l e s o u r c e s , i t i s o n l y p o s s i b l e t o make a few g e n e r a l i z a t i o n s a b o u t t h e o r i g i n s o f t h e g o l d . In t h e Upper F r a s e r sample, AU50d r e s e m b l e s h i g h Cu g o l d f r o m R e l a y C r e e k . None o f t h e C u - r i c h g o l d i n t h e F r a s e r R i v e r i s rimmed s u g g e s t i n g a l o c a l o r i g i n . The sample (an u n u s u a l l y l a r g e one) from F o u n t a i n Bar (AU52), shows wide d i s p e r s i o n a n d a p r o n o u n c e d Hg plume r i s i n g t o 6.38%. About 30% of t h e g o l d ( A U 5 2 c ) , i n c l u d i n g rimmed and unrimmed g r a i n s , c o u l d be o f C a r i b o o o r i g i n . The h i g h Hg g o l d i s 42 of unknown provenance, but conceivably unrimmed grains could be either of Bridge River o r i g i n , c a r r i e d by ice to the Upper Fraser and concentrated in outwash deposits (non rim forming) which are being reworked by the Fraser River, or from a source resembling those feeding the Bridge River but located along the Fraser River. The source of the rimmed, high Hg gold is unknown. The most s t r i k i n g feature of the L i l l o o e t sample i s the sudden appearance of AU11a, a high Cu gold that i s found in a l l samples between Relay Creek (AU15) and L i l l o o e t and the drop in the number of rimmed grains. The source could be Relay Creek (AU15). An alternative view i s that high copper gold i s being provided by gold lodes associated with ultrabasic rocks exposed along Bridge and Yalakom r i v e r s . The proportion of possible Bralorne gold (AU11b) i s high but i s reduced i f the part with <D.L. Hg i s assigned a Cariboo o r i g i n . The proportion of rimmed gold i s low (29% as compared to Fountain Bar with 58%) (Table 10) but increases downstream. The sample from Lytton (AU42) shows well the difference in fineness between rimmed and unrimmed gold. AU1b', with s i g n i f i c a n t copper, appears to represent a new source. The Yale (AU43) sample contains few rimmed grains. AU43a and AU43a' (they overlap) resembles Bralorne and Cadwallader (AU42). AU43b, high Cu, resembles AU11a (Relay). In the small Hope (AU75) sample, showing wide dispersion, rimmed grains make up 25%. 43 SUMMARY OF THE HISTORY OF PLACER TRANSPORT Bralorne lodes have apparently fed the placer at the mouth of Cadwallader Creek and have probably contributed to placers downstream to L i l l o o e t and perhaps beyond. High copper gold of the Relay Creek type appears at every sample s i t e between Bridge River and L i l l o o e t but i s absent at Fountain and not recognized in the lower Fraser River, except possibly at Yale where there are p o t e n t i a l ultrabasic sources. Rimmed grains have been found only in Fraser River, occurring at every placer s i t e , and are interpreted to be reworked gold which has been leached over a long period of time before entering the modern Fraser River sediments. Much Fraser River placer gold, e s p e c i a l l y unrimmed gold, has compositions that suggest derivation from the Cariboo but the ultimate o r i g i n of rimmed gold, gold with notable mercury, and gold of low fineness, remains unknown. 44 SOURCES: Speculations about the Lodes Although the lodes that supplied most of the placer are unknown i t is possible to make some deductions about the character of the lodes based on possible lode sources, previous work and the composition-fineness features of the source placer. The core analyses are considered to represent the primary composition of the gold grains. As mentioned e a r l i e r the study area can be divided into three regions on the basis of the geochemistry of the placer gold. This and the rive r drainage forms the basis of d i v i d i n g the area into two gold metallogenic provinces. AREA 1: CARIBOO This area produces gold with low Hg and low Cu. Because of the small sample size no conclusion can be drawn about the lode sources. AREA 2: BRIDGE RIVER The Bridge River area produces gold with high Hg and high Cu percentages. The lodes are t e n t a t i v e l y divided into two types, the Bralorne and the high Hg-high Cu type. Bralorne Type Mineralization in the area upstream of AU42 (Cairnes, 1937) consists of gold-quartz veins associated with faulted plutonic and ultrabasic rocks. These veins probably make up the source area for AU42. The most productive vein system was that of the Bralorne-45 Pioneer mine. Samples from this mine are taken to be examples of the Bralorne camp and support the following conclusions: 1 ) The gold from d i f f e r e n t veins shows a wider variation in composition (especially fineness) than gold from a single vein. Gold from a single vein may have a r e s t r i c t e d composition. 2) Each vein appears to have i t s own 'fingerprint' of fineness and Hg content. 3) As the vein samples were taken at one location on the vein no d i r e c t information on the variations along stri k e and with depth was obtained but a m i l l sample provides useful data. AU40 i s a sample from the crushing room floor of the 1961-1972 Bralorne cyanide only m i l l . During t h i s period of operation a r e s t r i c t e d number of veins were mined over a considerable depth. Individual vein populations can be distinguished in the AU40 diagram. The fineness range i s small, indicating that the change in fineness with depth i s probably small. This conclusion i s supported by the b u l l i o n fineness-depth plot for the mine (figure 3). Although the data are not very r e l i a b l e (Sharwood, 1911) because of poor records, changes in recovery techniques and mixing of gold from d i f f e r e n t veins, i t nevertheless suggests that the fineness ranged very l i t t l e with depth for gold mined during the period 1961-1972. The significance of the small increase with depth i s unknown. The average fineness for AU40 i s 851.16, which i s similar to the b u l l i o n data from figure 3. The generally r e s t r i c t e d spread of the Hg values in the veins i s i n t r i q u i n g . It has been noted above that the Hg values can vary quite widely from p a r t i c l e to p a r t i c l e and within a 46 p a r t i c l e . AU38 i s unreliable because contamination from a placer i s suspected. The plot for the Pioneer b u l l i o n data is also unreliable for t h i s purpose because the history of mining and mi l l i n g i s more confused than that of Bralorne. The exact location of AU21, 22 and 25 are unknown. They confirm the observation that the vein compositions range widely (Table 11). AU22 i s unusual in composition. In summary, AU42 i s made up of gold from quartz veins, each of which appears to have, i t s own c h a r a c t e r i s t i c f i n g e r p r i n t . Even though these veins .have a close s p a t i a l association they have d i f f e r e n t f i n g e r p r i n t s , implying a unique history of ore deposition for each. The c o l l e c t i v e array of compositions gives the AU42 d i s t r i b u t i o n . The s i m i l a r i t y of AU43 to AU42 i s s t r i k i n g . Veins a few kilometers to the north of Yale are a possible source. The lack of rimmed gold and and the geological setting support t h i s conclusion but the flatness of the gold argues against i t . High Hg ^ High Cu Type It has been observed that Cu-rich gold has a high fineness, usually >900. Data from a number of deposits containing Hg or high Cu are l i s t e d below. 1) Tulameen ( B r i t i s h Columbia): Cu-rich gold (to 30%) i s found in the Tulameen River and i s inferred to have been eroded from lodes in nearby ultrabasic rocks (Raicevic and Cabri, 47 1976). 2) Karabash deposit (Urals): Novgorodova and Tsepin (1976) c l a s s i f i e d t h i s deposit as a pyrite deposit with chalcopyrite. The deposits are located in one of the most t e c t o n i c a l l y altered zones of the Urals. The ore bodies were deposited in contact zones between rocks of d i f f e r e n t mechanical properties during the middle part of the upper Devonian tectonic-magmatic event. Mineralization occurred several times. Rakcheyev (1977) notes that the host rock i s a "chlorite-pyroxene-garnet" rock. Samples show a wide range of intragrain v a r i a t i o n of gold composition. Cu i s high and ranges widely and a Cu free amalgam i s associated with i t . 3) Zolotaya Gora (southern Urals)(may be the same as the above): The Zolotaya Gora deposits are hosted by "metasomatic chlorite-garnet-pyroxene after ultrabasic rocks" (Pokrovskii et a l . , 1974). Two discrete phases, Au-Cu and Au-Ag-Hg, were detected (Pokrovskii et a l . , 1979). 4) Kazakhstan deposit: Kazakhstan deposits are pyrite-Cu and pyrite-barite-polymetallic deposits with Au generally f i n e l y disseminated in sulphides. Supergene Au i s present. (Nesterenko et a l . , 1983). Au from a Au-Sb deposit contains 4-8%Hg (Naz'mova et a l . , 1979). 5) Donetsk Basin (Ukraine): High Cu gold i s reported by Kuznetsov et a l . (1977) from the Donetsk Basin. Kuznetsov (1982) reports Hg-rich gold in pyrite-arsenopyrite quartz, ankerite veins from Uleraine (sic) in the Ukraine. The Hg i s unevenly di s t r i b u t e d in the gold. 6) San Antonio mine (Manitoba): The San Antonio mine i s a 48 gold-quartz vein intruding a diabase s i l l (Boyle, 1979). Ferguson (1950) concluded from indir e c t evidence that the gold is Cu-rich. 7) Beni-Bousera (Morocco): Oen and Kie f t (1974) report a high-Cu gold associated with N i - r i c h minerals from the ultrabasic hosted ore bodies. 8) Bushveld Igneous Complex (South A f r i c a ) : Cu-rich gold occurs in a hortonolite-dunite pipe in the Bushveld Igneous Complex (Ramdohr, 1969). 9) Barberton (South A f r i c a ) : von Gehlen (1983) reports Hg from gold occurring in rocks of the Barberton s e r i e s . He also reports Hg-rich gold from the Witwatersrand deposit. 10) New Guinea: Stumpfl and Clark (1964) and Stumpfl (1964) report Cu-rich placer gold associated with placer p l a t i n o i d s in r i v e r s with headwaters in an ultrabasic complex. 11) Goodnews Bay (Alaska): Desborough (1970) reports Cu up to 2% in gold found in placers with platinum minerals. In summary the association of Cu-gold with basic-ultrabasic rocks seems to be' common. Hg i s commonly but not invariably associated with the Cu-rich gold and vica versa. Although no Pt was detected in the i n i t i a l 15-element study, the Pt, Cu-rich gold association i s noted. In the study area the association between Cu and Hg-rich gold in the Bridge River area i s strong, in pa r t i c u l a r for sample AU15. The AU48, AU15, and AU14 source placers are thought to represent lode sources which for the most part come from Cu and Hg-rich type of lodes. It i s possible that the high Cu and high Hg populations in AU15 may come from a single source rather 49 than two separate sources. It seems to be a safe deduction that prospecting for the lode sources of Cu-rich placer gold should concentrate on areas with abundant ultrabasic rocks. Prospecting for the Hg r i c h types should be concentrated along major f a u l t s or in nearby intrusives. If Hg and Cu are both present then a combination of the above i s indicated. The s t r u c t u r a l controls are probably the fa u l t s (thrusts and shears), extending at least to the upper mantle, that are commonly associated with the ultrabasic rocks. This i s supported by the general concensus that Hg i s associated with deep fault s (Jonasson and Boyle, 1972) and i s derived from the mantle, and that deep fa u l t s are common in the Bralorne area (Potter, 1983). The basic features pf Keays (1984) model to explain Archean lode gold deposits appear to be applicable to the Bralorne area. In particular the p a r t i t i o n i n g of gold into sulphide segregations in ultrabasic rocks and the subsequent remobilization of the gold during serpentinization, after transport to higher levels by f a u l t i n g (obduction), could explain both the gold compositions observed and the rock association inferred. The element associations demonstrated in th i s thesis provide a tool for discovering deposits of th i s type. In addition to the above the following are noted: 1) It i s possible that there i s a high-Cu source associated with the ultrabasics of the lower Bridge r i v e r . The Cu populations are not adequately explained by derivation from Relay (AU15). 2) The presence of the Cu-rich gold in the Tulameen river 50 area (Raicevic and Cabri, 1976) indicates that t h i s type of deposit is not limited to the Bridge river area. 3) There may be a connection between the Bralorne type and the high Hg-high Cu type. The Bralorne type has the same association with a major fa u l t and ultrabasic rocks as that expected for the high-Cu types but the gold composition and fineness d i s t r i b u t i o n is d i f f e r e n t . The a l b i t i t e at Bralorne may provide a key to t h i s connection as t h i s rock type i s mentioned by Keays (1984) as a way of i d e n t i f y i n g certain gold deposit types in the Archean. However i t should be remembered that 'same rock names' need not always mean 'same rocks'. 4) Ultrabasic rocks are located along lineations and faults between Yale, Tulameen and the Bridge River areas, suggesting that this whole area could be considered both a high Hg-high Cu, and Bralorne type metallogenic province. There i s also the p o s s i b i l i t y of an extension of t h i s NW-SE trending belt along the eastern margin of the Coast Plutonic Complex both north and south. 51 CONCLUSIONS 1) The microprobe is the best tool for the study of gold p a r t i c l e s because each phase making up the gold grain can be analysed separately and bulk analysis errors avoided. 2) Using the Ag, Cu, and Hg composition of gold i t i s possible to characterise lode gold deposits and to recognise gold from these lodes in nearby placers. The degree of fl a t t e n i n g of placer grains r e f l e c t s the degree of working and i n d i r e c t l y distance from and time since release from the lode source. 3) Although the transport of gold downstream has played a major role in the dispersion of gold in t h i s area, a simple transport model cannot account for a l l the populations of the placers found on that r i v e r . The role of undiscovered sources, intermediate c o l l e c t o r s , alternate transport mechanisms, changes in drainage and a l t e r a t i o n of the gold must a l l be considered in attempts to understand gold dispersion and the origins of present day placer gold. 4) The rimmed gold found in placers in the Fraser River formed in intermediate c o l l e c t o r s by leaching of Ag. Intermediate c o l l e c t o r sources are probably most important along the Fraser River. The role of intermediate c o l l e c t o r s in the other areas i s unknown. 5) Two metallogenic provinces can be i d e n t i f i e d : The Bridge River with high Cu and high Hg, and the Cariboo with low Cu and low Hg. 6) Within the Bridge River area two types of lode are postulated: The Bralorne type, and the high Hg-high Cu type. 52 High Cu-high Hg lodes seem to be related to ultrabasic rocks. High Hg gold (eg. Bralorne Type lode) seems to be associated with major f a u l t s . The association of both types of lode with ultrabasic rocks and major fault s suggests that there is a genetic relationship between them. 53 REFERENCES Antweiler, J.C., and Campbell, W.L. 1977. Application of Gold Compositional Analysis to Mineral Exploration in the United States. Journal of Geochemical Exploration. Vol. 8, pp. 17-29. Berman, Y. S., Botova, M.M., Bochek, L.I., Pleshakov, A.P. 1978. The Natural Series Gold S i l v e r . Geochem. Int. Vol. 15, No. 5, pp. 42-50. Boyle, R.W. 1979. The Geochemistry of Gold and i t s Deposits. Geological Survey of Canada B u l l e t i n 280. Cairnes, C E . 1937. Geology and Mineral Deposits of Bridge River Mining Camp, B r i t i s h Columbia. Geological Survey of Canada Memoir 213. Campbell, W.L., Mosier, E.L., and Antweiler, J.C. 1973. E f f e c t s of Laboratory Treatments on S i l v e r and Elements in Native Gold. J. Res. U.S. Geol. Surv. Vol. 1, No. 2, pp. 211-220. Chang, Y., Goldberg, D., and Neumann, J . 1977. Phase Diagrams and Thermodynamic Properties of the Ternary Cu-Ag-Au System. J. Physical and Chemical Reference Data. Vol. 6, No. 3, pp. 627-629. Colin, L.L. 1946. Gold Fineness in Relation to Geology -Consideration of the Macequece F i e l d . The South African Mining and Engineering Journal. Vol. 57, pt. 1, No. 2779, pp. 279-283. Davydov, A.S., and Goroshko, G.G. 1970. Comparative Characterics of Gold Fron Placer Deposits situated near the Pyrkanaisk Granite Massif, Western Chukota. Vop. Geol., Geokhim. Metallogen. Sev. - Zap. Sekt. Tikhookean. Poyasa, Mater. Nauch. Ses. 1969. I.N. Govorov, Ed, Dal'nevost. Geol. Inst., Vladivostok. USSR, pp. 271-275. (Also: Chem. Abstr. Vol. 75, 89986v) Desborough, G.A. 1970. S i l v e r Depletion Indicated by Microanalysis of Gold from Placer Occurrences. Western United States Economic Geology. Vol. 65, pp. 304-311. Desborough, G.A., Heidel, R.H., Raymond, W.H., Tripp, J. 1971. Primary D i s t r i b u t i o n of S i l v e r and Copper in Native Gold from Six Deposits in the Western United States. Mineral Deposits. Vol. 6, pp. 321-334. Desborough, G.A., Raymond, W.H., Iagmin, P.J. 1970. D i s t r i b u t i o n of S i l v e r and Copper in Placer Gold Derived from the Northeastern Part of the Colorado Mineral Belt. Economic Geol. Vol. 65, pp. 937-944. Fa y z u l l i n , R.M., and Turchinova, D.M. 1974. On Relationships between Gold Placers and Primary Sources or Intermediate 54 Collectors. Doklady of the Academy of Sciences of the U.S.S.R., Earth Science Section., Vol. 212(1-6), pp. 242-243. Ferguson, R.B. 1950. Red Gold fron the San Antonio Gold Mine, Bissett, Manitoba. Am. Mineral. Vol. 35, pp. 459-460. Fisher, M.S.1934-1935. The Origin and Composition of A l l u v i a l Gold, with Special Reference to the Morobe Gold f i e l d , New Guinea. Inst. Mining and Metallurgy, Transactions. Vol. 44, pp. 337-420. Fisher, N.H. 1945. The Fineness of Gold with Special Reference to the Morobe Gold F i e l d , New Guinea. Econ. Geol. Vol. 40, pp. 449-495 and 537-563. Fisher, N.H. 1950. Application of Gold Fineness to the Search for Ore. Australas Inst. Min. Metall. Proc. No. 156-157 pp. 185-190. Fit z g e r a l d , A.C., Graham, R.J., Gross, W.H., Rucklidge, J.C. 1967. The Application and Significance of Gold-Silver Ratios at Val D'or, Quebec. Econ. Geol. Vol. 62, pp. 502-516. Foster, R.L., Foord, E.E., and Long, P.E. 1978. Mineralogy and Composition of Jamison Creek Particulate Gold, Johnsville Mining D i s t r i c t , Plumas County, C a l i f o r n i a . Econ. Geol. Vol. 73, No. 6, pp. 1175-1183. Gay, N.C. 1963. A Review of the Geochemical Characteristics of Gold in Ore Deposits. Univ. Of Witwatersrand, Johannesburg. Econ. Geol. Res. Unit. Info. C i r c u l a r No. 12. Von Gehlen, K. 1983. S i l v e r and Mercury in Single Gold Grains from the Witwatersrand and Barberton, South A f r i c a . Mineralium Deposita. Vol. 18, pp. 529-534. Holland, S.S. 1950. Placer Gold Production of B r i t i s h Columbia. B r i t i s h Columbia Department of Mines. B u l l e t i n No. 28. Jonasson, I.R., and Boyle, R.W. 1972. Geochemistry of Mercury and Origins of Natural Contamination of the Environment. Can. Inst. Min. Metall. B u l l . Vol. 65, No. 717, pp. 32-39. Keays, R.R. 1984. Archaen Gold Deposits and Their Source Rocks: The Upper Mantle Connection. In Gold 82: The Geology, Geochemistry, and Genesis of Gold Deposits., Geol. Soc. Zimbabwe Spec. Pub. No.1, pp. 17-51. Kikuchi, R., Sanchez, J. De Fontaine, and Yamauchi, H. 1980. Theoretical Calculation of the Cu-Ag-Au Coherent Phase Diagram Acta Metallurgica. Vol. 28, No. 5, pp. 651-662. Koshman, P.N., and Yugay, T.A. 1972. The Causes of Variation in Fineness Levels of Gold Placers. Geochemistry Internat. 55 Vol. 9, pp. 481-484. Kuznetsov, Yu.A., Panov, B.S., Samoilovich, L.G., Sharkin, D.P., Lazarenko, E.K.(ed.) 1977. Cuprous Gold in the Donetsk Basin. Voprost Regional'noi I Geneticheshoi Mineralogii (Obsuzhdavshiesya na s'ezde Ukrainskogo Mineralogicheskogo Obshchestva) Held 1975. Naukova Dunka, Kiev, pp. 59-63. (Also: Chem. Abs. Vol. 88, 173534X.) Kuznetsov, Yu.A., Sharkin, O.P., Samoilovich, L.G. 1982. New Findings of Mercurous Gold in the Ukraine. Mineralogicheskii Zhurnal. Vol. 4, No. 2, pp. 72-74. (Also: Chem. Abs., Vol. 97, 041726n.) Lay, D. 1940. Fraser River Tertiary Drainage - History in Relation to Placer-Gold Deposits. B r i t i s h Columbia Department Mines, B u l l . , No. 3, 30pp. Mertie, J.B., J r . 1940. Placer Gold in Alaska. Washington Acad. S c i . Jour., Vol. 30, pp. 93-124. Naz'mova, G.N., Spirodonov, E.M. 1979. Mercury-Gold (Kazakhstan Deposit) Dokladylaidemii Nauk, SSSR (Mineral) Vol. 246, No. 3, pp. 702-705. (Also: Chem. Abs. Vol. 91, 110367m.) Nesterenko, G.V., Kuznetsova, A.I., Lavrent'ev, Yu.G., Pospelova, L.N. 1982. Variations in Macrocomposition Important Typomorphic Features of Native Gold. Geologiya I Geofizika., No. 3, pp. 57-65. (Also: Chem. Abs. Vol 97, 009345b.) Novgorodova, M.I., and Tsepin, A.I. 1976. Phase Compositions of Cupriferous Gold. Acad. S c i . USSR, Dokl., Earth S c i . Sect. Vol. 227, 1:6, pp. 121-123. Oen, I.S., and K i e f t , C. 1974. Nickeline with Pyrrhotite and Cubanite Exsolutions, Ni-Co-Rich L o e l l i n g i t e and an Au-Cu-Alloy in Cr-Ni-ores from Beni-Bousera, Morocco. Neues Jahrbuch Fur Mineralogie, Monatshefte, pp. 1-8. Petrovskaya, N.V. 1971. Growth and Subsequent Changes in Native Gold Crystals i_n International Mineralogical Association, 7th General Meeting, Papers and Procedings. Mineral. Soc. Jap. Spec. Pap. No. 1, pp. 116-123. Pokrovskii, P.V., and Berzon, R.D. 1974. Composition of Copper and S i l v e r Gold from the Deposit Zolotaya Gora. Ezheg., Inst. Geol. Geokhim., Akad. Nauk SSSR, Ural. Nauchn. Tsent., pp. 94-97. (Also: Chem. Abstr. Vol. 86, 7236r.) Pokrovskii, P.V., Murzin, V.V., - Berzon, R.O., Yunikov, B.A. 1979. Mineralogy of Native Gold from the Zolotaya Gora ^ Deposit. Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva. Vol. 108, No. 3, pp. 317-326. (Also: Chem. Abstr. Vol. 91, 143452p.) 56 Potter, C.J. 1983. Deformation and Metamorphism Related to Accretion of an Ocean-Marine Terrane in Southern B r i t i s h Columbia. Geol. Soc. Am. Abstr. W/ppms. ABS 15566. Vol. 15, No. 5, pp. 385. Ramdohr, P. 1969. The Ore Minerals and Their Intergrowths. Pergamon Press, pp. 321-336. Raicevic, D., and Cabri, L.J. 1976. Mineralogy and Concentration of Au- and Pt-Bearing Placers from the Tulameen River Area in B r i t i s h Columbia. Can. Inst. Min. Metall. B u l l . Vol. 69, No. 770, pp. 111-119. Rakcheyev, A.D. 1977. Geology and Structure of the Karabash Pyrite Deposits in the Urals By u l l e t i n Moskovskogo Obshchestua Ispytateley Prirody, Otdel., Geol. Vol. 52, No. 4, pp. 20-37. (Also: Chem. Abstr. Vol 88, 173672r.) Roddick, J.A., and Hutchison, W.W. 1973. Pemberton (East Half) Map-Area, B r i t i s h Columbia. Geol. Survey of Canada. Paper 73-17 with map 13-1973. Rolfe, C , and Hume-Rothery, W. 1967. The Constitution of Alloys of Gold and Mercury. Journal of the Less Common Metals. Vol. 13, pp. 1-10. Sharwood, W.J. 1911. Analysis of Some Rocks and Minerals from the Homstake Mine, Lead, South Dakota. Econ. Geol. Vol. 6, pp. 729-789. Smith, P.S. The Fineness of Gold in the Fairbanks D i s t r i c t , Alaska. Econ. Geol. Vol. 8, No. 5, 1913, pp. 449-454. Stumpfl, H. 1964-65. Electron Probe Microanalysis of Au-Pl a t i n o i d Concentrates from Southeast Borneo. I n s t i t u t i o n of Mining and Metallurgy Transactions, Section B, Vol. 74, pp. 933-946. Stumpfl, H., and Clark, A. 1966. Electron-Probe Microanalysis of Gold P l a t i n o i d Concentrates from Southeast Borneo, Discussion. I n s t i t u t i o n of Mining an Metallurgy Transactions, Section B, Vol. 75, pp. B97. Tishchenko, E.I. 1981. The Problem of the Evolution of Gold-Flake Flattening in A l l u v i a l Placers. Soviet Geology and Geophysics. Vol. 22, No. 10, pp. 28-33. Tishchenko, E.I., and Tishchenko, M.D. 1974. Co e f f i c i e n t of Flatness of Gold in Placers. Razved. Okhr. Nedr. No. 3, pp. 52-54. (Also: Chem. Abstr. Vol. 81, 66387r.) Trenina, T.I., and Shumilov, Yu.U. 1970. Natural Gold Amalgam in Some Placer Deposits of the B i l i b i n s k Area. Kolyma, No. 2, pp. 40-41. (Also: Chem. Abstr., Vol. 74, 44l65q.) Uglow, W.L., and Johnston, W.A. 1923. Origin of the Placer Gold 57 of the Barke r v i l l e Area, Cariboo D i s t r i c t , B r i t i s h Columbia, Canada. Econ-. Geol. Vol. 18, pp. 541-561. Valpeter, A.P., and Davidenko, N.M. 1969. C r i t e r i a of Placer Deposit Relation to Parental Rocks. Probl. Geol. Rossypei. Soveshch., (Dokl.) 3rd, pp. 116-124. (Also: Chem. Abstr. Vol. 75, 38853s.) Wang, W., and Poling, G.W. 1983. Methods for Recovering Fine Placer Gold. C.I.M. Dec. Warren, H.V., and Thompson, R.M. 1944. Minor Elements in Gold. Economic Geology. Vol. 39, No. 7, Nov., pp. 457-471. Warren, H.V. 1979. Supergene Gold Crystals at Stirrup Creek, B.C. Western Miner, June, pp. 9-14. Yablokova, S.V. 1972. New Morphologic Variety of Gold and i t s Origin. Doklady Acad. S c i . USSR.., Earth S c i . Sec. Vol. 205, pp. 143-146 (Am. Geol. Inst. Transl.) Yablokova, S.V., and Rhyzbov, B.V.1972. Role of Ancient Gold in the Feeding of Quaternary Placers of the Mari Taiga. Izv. Vysch. Ucheb. Zaved. Geol. Razaved. Vol. 15, No. 10, pp. 60-65. (Also: Int. Geol. Rev. Vol. 15, No. 10, pp. 1182-1185.) Yeend, W. 1975. Experimental Abrasion of D e t r i t a l Gold. J . Research U.S. Geol. Survey. Vol. 3, No. 2, Mar.-Apr., pp. 203-212. Yushmanov, V.V. 1972. Genesis of Gold Placers in the Western Part of the Stanovoi Ridge. Zap. Zabaikal. F i l i a l a . Geogr. O-Va. SSSR. Vol. 86, pp. 104-107. (Also: Chem. Abstr. Vol. 82, 6 2 0 1 4 j . ) Z a r i t s k i i , R.M., Vetrov, Yu.I., Zlobenko, I.F., Mazur, A.R., Samoilovich, L.G. 1980. Occurrence of Gold in the Alluvium of Early Cretaceous Buried Valleys in the ventral Part of the Ukrainian Shield. Geologicheskii Zhurnal, Vol. 40, No. 3, pp. 149-150. (Also: Chem. Abstr. Vol. 93, 050851U.) TABLE 1: Sample Detai1s Sample Sample Number Name No. Of L o c a t i o n A n a l y s e s Source & Comment Au 01 L y t t o n 73 W. S i d e of F r a s e r J u s t above L y t t o n f e r r y Panned Au 11 L l l l o e t t 62 J u s t below o l d b r i d g e Into L l l l o e t t On Horsebeef Bar S l u i c e d . C o l l e c t e d i n Nov. & Feb. Au 12 Lower B r i d g e 70 Half-way between Moon & A p p l e s p M n g Ck. On B r i d g e R i v e r Donated. From a 10' bench Au 13 B r i d g e Yalakom J u n c t i o n 34 On S. S i d e of B r i d g e R. d i r e c t l y o p p o s i t e Yalakom R. mouth Donated. From a 50' bench Au 14 Yalakom 45 On Yalakom R. Above Yalakom Ck. Donated. Au 15 R e l a y 40 On Relay Ck. J u s t above P a r a d i s e Ck. Donated. Au 17 Car 1boo G o l d Qtz. Mine D e t a i l s unknown. UBC G e o l . Museum. No. 1153 Au 18 B a s s f o r d Ck. 19 B a s s f o r d Ck. At P e t e r s Ck. Donated. Au 19 L i g h t e n i n g 43 W1ngdam/Stanley on L i g h t e n i n g Ck. Donated. Au 21 C o r o n a t i o n C o r o n a t i o n Group, B r a l o r n e D e t a i l s unknown. UBC G e o l . Mus . No. S-74-1113 Au 22 B r a l o r n e B r a l o r n e Mine, D e t a i l s unknown. UBC G e o l . Mus. No. S-74-1131 Au 25 P i o n e e r 1 P i o n e e r Mine. D e t a i l s unknown. UBC Geo l . Mus. No. S-74-12 04 59 T a b l e 1. c o n t i n u e d Sample Number Sample Name No. Of A n a l y s e s L o c a t i o n Source & Comment Au 33 K i n g Curve K i n g Curve v e i n 1/2m q u a r t z v e i n on 800' l e v e l B r a l o r n e Mine Large specimen. Au 34 A1hambra Alhambra v e i n , 2150' In on 800' 1 e v e l B r a l o r n e Mine Large specimen. Au 37 851 v e i n 851 v e i n 1m q u a r t z v e i n on 800' l e v e l B r a l o r n e Mine Large specimen. Au 38 P toneer M11 1 21 O l d P i o n e e r Mine M i l l below lower c r u s h e r near s e t t l i n g tank I n d i c a t i o n s of P l a c e r h a v i n g been through system Au 40 B r a l o r n e Ml 1 1 41 D r a i n a g e Channel below c r u s h e r s M111 worked 1961-71 Au 42 C a d w a l l a d e r 76 W i l l Crawford's c l a i m On N. Fork of H u r l e y R. above Haylemore Donated. Au 43 Y a l e 75 West end of town, N. Shore Purchased. Au 45 Upper B r i d g e 87 1-1/2 km up B r i d g e R. from Moha Purchased. Au 48 St 1rrup 55 S t i r r u p Ck. From h a l f - m i l e s t r e t c h a t 5600' Donated. Au 50 Upper F r a s e r 94 1/2 km above W i l l i a m s S l u i c e d . L k . - A l e x i s Ck. Rd. B r i d g e On the F r a s e r R. Au 51 B1g Bar 39 N. End of Bar, south Of f e r r y & farmhouse On F r a s e r R. S l u i c e d . T a b l e 1. c o n t i n u e d 60 Sample Sample Number Name No. Of L o c a t i o n A n a l y s e s Source & Comment Au 52 F o u n t a i n 145 Water l e v e l sample a t F o u n t a i n Bar on F r a s e r R. Purchased. Au 52R F o u n t a i n R1m 18 As above As above. Au 59 N e l s o n 20 N e l s o n Ck., C a r i b o o . Donated. D e t a i l s unknown Au 60 S o v e r e i g n 20 S o v e r e i g n , C a r i b o o , Donated. D e t a l 1 s unknown Au 75 Hope 58 On west shore, F r a s e r , S l u i c e d . O p p o s i t e N.• P o i n t of Hope I s . Approx. 2km, below b r i d g e 61 TABLE 2: C r y s t a l s Element L i n e s and A n a l y t l e a l Element and L i n e C r y s t a l Background S t e p o f f (On unknowns) AuMa i PET 6 0 0 *Hg»0 PET 150 AgLa i PET 6 0 0 CuKa i LIF 3 0 0 * T h i s 1 c o u n t s a t i n e gave b e s t low l e v e l s . i n t e r f e r e n c e f r e e TABLE 3 : S t a n d a r d s E1ement Compos 111on Source Background S t e p o f f (On S t a n d a r d s ) Au 100% NBS S t a n d a r d r e f e r e n c e m a t e r i a l 481 600 Hg HgTe Comlnco E l e c t r o n i c s m a t e r i a l 400 Ag 100% NBS S t a n d a r d r e f e r e n c e m a t e r i a l 481 600 Cu 100% M e t a l l u r g y U.B.C. 481 500 TABLE 4: Detection Limits at 99% confidence for 1 analysis Wt% Hg1 Cu' Hg' Cu ! Low Density (Low Fineness 600) .059 .042 .063 .048 High Density (High Fineness 990) .060 .045 .062 .052 Detection Limit Formu1 a 'Det L1m = 3 * Background Unknown * Wt% STD Counts/sec STD 2.326 /2 x Background (Cps) 'Det Lim = CPS per Wt%, STD * yTJounting Time, unknown(=20) From Le Maltre R. Numerical Petrology, Elsevier, 1982. TABLE 5: Core-Core Duplicates F i r s t Analysis Second Analysis Sample No. Au Hg Ag Cu Total F ineness Au Hg Ag Cu Total F1neness Au 50-4-1 100. 1 1 0 .34 .02 10O.47 996.6 97 .63 .23 1 . 23 . 1 99. 19 987 .6 Au 20-1-1 83.63 .02 16 .69 0 100. 32 833.79 81 .78 0 16 .99 .02 98.79 827.98 Au 20-1-2 B2.58 0 18 .52 .01 101.12 816.81 81 . 12 .01 18 .29 .04 99.45 816.0 Au 20-1-5 85.92 .01 15 .59 .06 101.58 846.41 82 .37 .03 15 .67 .04 98. 1 1 840.17 Au 20-1-18 80.85 0 20 . 35 .02 101.22 798.91 77 . 14 .02 22 .55 .03 99.74 773.79 78 .69 0 20 .5 0 99. 19 793.32 Au 43-3-5 35.51 2 .84 62. 06 0 1O0.41 363.96 35 .47 2.09 61 . 49 0 99.05 365.82 AU 48-1-24 96.27 O 5. 6 . 1 99.98 943.93 94. 76 .02 5. 67 . 11 1O0.56 943.54 94. 5 .04 5. 33 .09 99.96 946.60 Au 43-3-22 88.76 .03 1 1 . 42 .01 1O0.22 886.00 88. 45 .05 1 1 . 54 .05 100. 1 884.59 Au 42-2-20 85.04 .09 13.94 .08 99.07 859.16 87.71 0 13.12 .02 10O.84 869.8 Table 5. continued F i r s t Analys is Second Ana lys i s Sample No. Au Hg Ag Cu Total F ineness Au Hg Ag Cu Total F1neness Au 42-1-5 85 .25 . 15 15 .27 .01 100.68 848.09 85 .23 . 17 15 .47 0 100.88 846.37 84 .2 .28 15 .85 0 100.33 841.57 84 .78 . 13 15 .55 0 100.45 845.01 Au 42-1-8 81 .71 .09 18 .56 .01 100.37 814.9 82 .67 0 9 17.49 .03 100.18 825.37 Au 45-1-5 89 . 19 2.99 7 . 1 1 .06 99.35 926 . 16 89 .28 2.53 7 .22 .07 99.09 925.18 Au 45-1-B 84 . 7 .02 15 . 13 .04 99.88 848.44 83 48 .05 15 .09 .07 98 .69 846.91 Au 45-1-9 79 .01 .23 20. 18 .06 99 49 796.55 78. 8 .2 20. .43 .02 99.46 794. 12 Au 45-1-10 88 .06 .31 10. 84 .06 99.28 890.39 87 . 51 .24 10. 8 .05 98.6 890.14 Au 45-4-2 88 6 .91 9. 99 .02 99.53 898.67 88. 2 .85 10. 23 .04 99. 32 896.06 Au 45-4-22 91 . 35 .65 6. 58 .08 98 .66 932.81 91 . 46 .61 6. 72 .06 98.85 931.55 Au 45-1-4 77 . 37 . 12 23. 22 .02 100.74 769.16 79. 7 . 12 23. 23 .Ol 100.07 767.53 Au 43-2-11 90. 0 .35 9. 28 .07 99 .69 906.53 90. 31 . 15 9. 18 .06 99.69 907.73 Table 5. continued F i r s t Analysis Second Analysis Sample No. Au Hg Ag Cu Total Fineness Au Hg Ag Cu Total F1neness Au 52-4-7 81 . 49 .26 17 . 4 .02 99. 17 824.04 81 . 77 .33 17 . 38 .04 99.51 824.71 Au 52-4-8 89 .67 .04 9 .87 .04 99.62 90O.84 88 . 47 . 12 9 .81 .06 98.46 900.18 Au 52-4-9 92 .21 0 7 .76 .07 100.04 922.37 92 .6 0 7 .81 .07 10O.49 922.22 Au 52-4-10 95. 37 0 4. .55 .09 1O0 954.46 94 .67 0 4 . 61 .03 99. 31 953.56 Au 75-3-12 94.8 O 5.62 .15 10O.58 944.04 95.58 0 4.43 .15 10O. 15 955.70 Au 33-1-1 80.59 .06 19.27 0 99.94 807.03 80.75 .08 19.45 0 10O.28 B5.88 TABLE 6: Core-Rim Duplicates Core Rim Sample No. Au Hg Ag Cu Total Fineness Au Hg Ag Cu Total F1neness Au 48-1-25 92 .22 . 1 1 7.36 .09 99.77 926.09 90.99 .96 7.21 .06 99.22 926.57 91.51 .01 7.37 . 14 99.03 925.46 Au 48-1-24 94 .27 0 5.6 . 1 99.98 943.92 92.94 .24 5. 36 .09 98.63 945.47 Au 43-3-26 89 .36 . 15 10.95 .05 100.51 890.84 88.81 . 1 1 10.63 .03 99.59 893.10 Au 42-1-5 85. 25 . 15 15.27 .01 100.68 848.09 84.4 .32 14.34 0 99.05 854.77 Au 42-1-4 76. 48 .07 24.21 .04 100.8 759.55 76.74 .04 23. 31 .01 100.11 767.01 Au 42-1-3 77 . 95 .22 22 .39 O 100.55 776.86 77 .23 .26 22 .41 .01 99.99 775.09 Au 42-1-8 81 . 71 .09 18.56 .01 100.37 814.9 84 . 19 . 14 15.46 .01 99.79 844.85 Au 01-4-28 81 . 41 .07 19.83 .05 101.43 804.12 80.92 .07 19.74 .05 100.83 803.89 Au 12-2-8 70. 71 .01 .26 31 .07 102.05 996.33 68.85 .04 .27 30.91 100.07 996.09 T a b l e 6. c o n t i n u e d Core R1m Sample No. Au Hg Ag Cu T o t a l F i n e n e s s Au Hg Ag Cu T o t a l F i n e n e s s Au 12 -2 -7 83 .92 1 .55 14 . 19 .03 99.69 855 .36 83 .89 1 .2 14 .31 .04 99 .45 854 .27 Au 12-2-6 84 .7 .03 16 .31 .06 101.09 838 .53 84 .7 . 11 16 .29 .07 101 . 17 838 .69 Au 12-2-5 85 .56 2 .45 12 .23 .07 100.31 874 .93 84 .31 2 .52 12 .5 .06 99 .4 870 88 Au 45 -1 -25 87 .24 . 14 12 .51 . 15 100.05 874 .58 86 .76 . 19 12 .64 .06 99 .65 872 .83 Au 50-2-21 84 .02 .08 16 .01 0 100.12 839 .94 83 .98 .08 16 .06 0 100 . 12 839 .46 Au 50 -2 -24 82 .98 .25 16 89 .04 100.14 831 .04 83. .27 .28 16 .43 .02 100 835. .20 Au 4 3 - 1 - 1 9 72. 93 .35 26. 59 .01 99.88 732. .81 73. . 14 .36 26. ,76 0 100. 27 732. 13 Au 43 -1 -17 79. 69 1 . 18 18. 08 .02 98.97 815. 07 78. 83 1 . . 17 17. 7 .01 97. 21 815. 68 Au 43 -1 -12 88. , 11 1 .62 9. 81 0 99.53 899. 81 88. 62 1 . 61 9. 9 .02- 100. 15 899. 5 Au 4 3 - 1 - 5 87. .77 .03 11 . 66 .02 99.48 882. 73 86. 94 01 11 . 6 .03 98. 58 882. 28 Au 4 3 - 3 - 5 35.51 2.84 62.06 0 100.41 363.94 35.34 4.08 61.76 0 101.17 363.95 —1 TABLE 7: F i n e n e s s Compar i son Sample Name * B u l l e t i n 28 Name Average F i n e n e s s T h i s Work B u l l e t i n 28 F i n e n e s s Au 48 Watson Bar 930 892 Au 43 Stwash 843 868 Au 12 Marsha l 1 863 846 Au 11 F r a s e r R i v e r 826 855 * Hoi l a n d , S.S. , B.C.D.M. Bui 1. No. 28. 1950. CO TABLE 8: Rim-Core Compositions Core Rim Sample No. Au Hg Ag Cu Total F1neness Au Hg Ag Cu Total F1neness Au 52-3-6CB) 80 .89 . 18 19.89 .03 100.99 802.63 97 .35 .01 2.82 .02 1O0.21 971.85 Au 52-3-1KB) 77 .2 .25 23.47 .04 100.96 766.86 98 .05 . 14 .85 .02 99.07 991.40 Au 52-3-12(B) 90 .62 .05 9.81 .03 100.52 902.32 98 .64 .01 .64 O 99.29 993.55 Au 52-2-3(B) 82 .08 .08 18.27 0 100.44 817.93 97 .5 .04 1 . 18 .01 98. 72 988.04 Au 52-2-4(B) 75 .41 .56 24.08 .01 100.05 757.96 98 .69 .01 1 .39 .02 100. 1 986.11 Au S2-2-9(B) 80. .41 .5 18.37 .02 99.3 814.03 99. . 13 O .85 .02 100 991.49 Au 52-2-13(B) 80. 53 . 12 18.54 .01 99.2 812.86 96. 9 0 2.88 0 99.78 971.13 Au 52-2-23(R) 80. 75 .94 17.97 .02 99.67 817.97 98. 92 0 .77 O 99.69 992.27 Au S2-1-7B 88. 46 .02 10.47 .04 98.99 894.16 98. 16 0 .79 .04 98.95 992.01 Au 52-1-17B 88. 74 0 12.3 .08 101 . 13 878.26 98. 24 .01 1 .29 0 99.55 987.04 Au 52-1-19B 82. 3 .07 16.89 0 99.26 829.72 97. 93 0 1 .93 .04 99.9 980.67 cn Table 8. continued Core Rtm Sample No. Au Hg A9 Cu Total Fineness Au Hg Ag Cu Total Fineness Au 52-1-22B 90 .67 .06 8.35 .08 99. 16 915.67 98.13 .03 1.34 0 99.5 986.53 Au 52-5-8B 87 . 16 1 .27 10.92 .01 99.37 888.66 94 .3 .54 5.48 .03 100.35 945.08 Au 52-5-1 IB* 79 58 .51 20.27 0 1O0.37 796.99 55.91 37. .88 .02 93.81 984.50 Au 52-5-15B 85 48 . 12 14.67 .02 100.32 853.34 97.33 .03 2.56 .02 99.93 974.37 Au 52-G-6B 76. 64 . 14 22.66 .02 99.45 771.80 99.27 O 1. 1 0 100.38 989.04 Au 52-4-13B 84 .6 .97 13.56 .03 99. 17 861.85 98.09 0 1. 19 .04 99.31 988.01 Au 52-4-26 86 .25 .01 12.73 .03 99.03 871.39 95.44 0 3.57 .02 99.03 963.94 Au 01-4-28 80. 92 .07 19.74 .05 1O0.83 803.89 100.13 .02 .63 .09 100.89 993.75 Au 02-2-24 90.89 .03 9.15 .08 100.14 908.53 100.37 .02 .54 .04 100.97 994.64 * Hg Rim 71 TABLE 9: Hg C o n t a m i n a t i o n Tea t Sample Number 0 Au Hg Ag Cu T o t a l F i n e n e s s O r i g i n a l 81.01 2.36 16.45 O 99.82 .831.21 Au 1 1 - 2 - 7 R e p o l l s h 80.38 1.83 15.91 .03 98.15 834.77 - 1 0 Removed * O r i g i n a l Au 11 -2 -8 R e p o l l s h 86 .17 1.54 10.6 0 98.31 890.46 - 1 0 Removed 87.44 1.19 10.78 .09 99 .49 890.24 O r i g i n a l 78.79 10.52 8 .03 97.34 907.82 Au 1 1 - 2 - 1 0 R e p o l l s h 78.97 9.28 6 .02 94.27 929.38 - 1 0 Removed O r i g i n a l 72.73 .2 26.96 .03 99.92 729.56 Au 11-2-11 R e p o l l s h 72.47 .11 27.57 0 100.15 724.41 - 10 Removed 74.21 .15 25.05 0 99.41 747.63 O r i g i n a l 79.45 .79 20.71 O 100.94 793.23 Au 11 -2 -12 R e p o l l s h e d 76.88 .79 20.8 0 98.47 787.06 - 10 Removed * A f t e r Au 11 -2 -10 has been removed. 72 TABLE 10: R1m D i s t r i b u t i o n Sample Number Au50 Au51 Au52 Au11 Au01 Au43 Au75 % of T o t a l Number o f P a r t i c l e s w h i c h a r e Rimmed 40.4 37.5 58 .0 28.8 41.7 9.9 33.3 % o f Rimmed P a r t i c l e s wh ich a r e > 20% Rimmed 34.2 72.2 58.S 2 1 . 0 74.3 20 42 .3 % o f T o t a l Number o f P a r t i c l e s Which a r e > 20% Rimmed 13.8 27.1 34 .0 G.1 30.9 2.0 14.1 T o t a l Number o f P a r t i c l e s In Mount 94 48 150 66 84 101 78 Rimmed P a r t i c l e s 38 18 87 19 35 10 26 > 20% Rimmed P a r t i c l e s 13 13 51 4 26 2 1 1 TABLE 11: Lode G o l d Au Hg Ag Cu T o t a l F i n e n e s s B r a l o r n e Au 21 86 .22 . 1 13 .78 .03 100. 23 862 .2 Au 22 96. 29 .07 3. 38 1 .08 100. 85 966 .09 Au 25 82. 87 .25 16. 2 .04 99. 47 836 .48 C a r i b o o Au 17 94 .39 0 4.38 .05 99.85 955.6 74 PLATE 1 Plate 1a : AU48-2 i s an example of angular, unflattened grains, (reflected l i g h t image). 1b : AU52-2 i s an example of smooth, flattened grains, (reflected l i g h t image). 75 76 PLATE 2 Plate 2a : AU52-3-6 shows the smooth contact between core and rim, (backscattered electron image). 2b : AU52-2-9 shows the smooth contact between core and rim, (backscattered electron image). 2c : AU52-5-15 shows the smooth contact between core and rim, (backscattered electron image). 2d : AU52-1-18 shows high fineness gold along cracks, (backscattered electron image). 77 78 PLATE 3 Plate 3a : AU52-1-21 shows high fineness gold along cracks, (backscattered electron image). 3b : AU52-4-26 shows the uniform thinness of the rim on straight sections and thickening along external bends, (backscattered electron image). 3c : AU52-3-12 shows islands of o r i g i n a l gold separated by rim gold, (backscattered electron image). 3d : AU52-4-13 shows islands of o r i g i n a l gold separated by rim gold, (backscattered electron image). 7 9 8 0 PLATE 4 Plate 4a : AU52-2-20 shows islands of o r i g i n a l gold separated by rim gold, (backscattered electron image). 4b : AU52-4-15 shows lenses of rim gold within a gold p a r t i c l e , (backscattered electron image). ( 8 1 82 Figure 1: Sample Location Cu Weight % Au Figure 2a: Experimentally Derived Solvus at Various Temperatures for the Cu-Ag-Au Ternary (after Chang et a l . 1977). MESH NUMBER 300 200 ISO 100 65 46 39 28 20 14 10 8 _J I I I I I _J • ' • ' ' 0.05 0.074 0 10 0.15 0.21 0.30 0.42 0.60 0.83 1.20 1.6 2.40 Au PARTICLE SIZE (mm) Figure 2b: Recovery of Different Size Au P a r t i c l e s by Gravity Devices (after Wang and Poling, 1983). 84 1 9 2 2 - 1 1930 H 1940 H DC < UJ 1950 H 1960 H 1970 H 1972 F i g u r e 3: B r a l o r n e B u l l i o n F i n e n e s s N e w mi l l , p r o p e r t i e s c o n s o l i d a t e d Amalgam f ree r e c o v e r y C y a n i d e mill B r a l o r n e - P i o n e e r c o n s o l i d a t e d New mill C y a n i d e only 7 0 0 8 0 0 FINENESS 9 0 0 1910 -i 1920 H 85 Figure 4: Pioneer B u l l i o n Fineness < GC LU 1940 H 1950 H C y a n i d e Mill 1930 i 932 1960 700 -i r 800 FINENESS 900 00 CO AU01 CM CO X ia a" o " CM + + + T + - i . , ~~I 1 1 1 1 1 1 1 1—"T 600 700 800 FINENESS 00 CO -t-|! Hp+-900 CD X ca 'a a CM Figure 5b: Lytton 1000 oo - j 03 Ul CM CJ CO o" CO o" CM AU01 ' : . i — i — i — ( ' * I *t I Y 600 700 800 FINENESS CO CM ZD CJ co Figure 5c CM Lytton <f2 1Q00 89 T3 OJ u 3 60 C o 4-1 4-1 £9H 9"! 9T VI ZT OT 9*0 9*0 fr"0 2'0 I I i i I | I I I I I I | J 1 i i OT) O Z) < U3 CM oa to a 'a CM ' a i—1 r*—i 1 1 M ^ H — h r 8 - 1 r J L - j y¥f 4,—II |rWrl 8' I 9T K l ZT OT 9TJ *3H 9*0 fr'O ZTJ 0*0 CO U3 CD AU01C + + + + "i r ~ — i — r 600 700 i 1 — i r T BOO FINENESS 900 i 1 1 r + CO to CM CO CD o a a Figure 5e: Lytton (Rimmed) a a 1000 o CD CO AU01U CO X CO i 1 1 r 600 700 "i 1 r \ r -800 FINENESS i 1 r ta CM CO CD o CJ CM o Figure 5f: Lytton (Unrimmed) 900 1000 I—1 10 AU02 CM CD X CO o " + •+ + + 600 i r — r ^ - r 700 1 r — ^ + .4 i r BOO FINENESS - i — r 900 T 1 t^l + + co CO CM CD X co " o CM Figure 6b: Gold Pan 100? vo co CO CO CO AU02 CO 3 H CM ZD CJ co co co o " " o 600 + + i 1 r 700 +v + ++ + i i ' i n — r * BOO FINENESS + •+ T 900 CM " a 1000 Figure 6c Gold Pan 95 o vO c CO 0) PU U 3 T3 oO rH •H O O 8T 9T t>T 2T OT 9'0 9'0 t?Tj Z' 0 0*0 I _L_ I I I l_ I I I I I 1 0 0 CM O ID < + 10 IN ca 'a ••2 + + + + + t + < i 1 1 1 1 1 1 1 i 1 1— i 1 1 r*—i 1 f ? • 8T 9T >T Z'l OT 9TJ 9TJ fr'O ZTJ 0*0 *3H to CM to o " AU11 A A 600 T \—n 1 r»—i r«—r 700 -t + +4-800 FINENESS 1 1 r "i 1 r 900 - f ^ - f — r CM CD CD 'a Figure 7b: L i l l o e t t 1000 vo 03 AAA A A— to AU11 CM ZD C J CM o + +, -*i r 600 700 S i *- +|—• 600 FINENESS + + 4 44 4 i r 900 ~i 1 1 r co CM ZD CJ ta a 1000 Figure 7c: L i l l o e t t VO 00 99 T3 r~ 4J 4J 0) OJ U. O 3 rH OO rH •H -rt 8T 9T frT ZT I I I I I I l _ *9H OT B'O 9*o v o z'o cro J I I I I I . I I I I I co < + CM h 3 CO CO ' o CM ' O + 8T i—i—i—r-9T frT i—i—i—i—i—r—i—i—i—r—v i ZT OT 9TJ 9'0 f O 10 *9H • "0 CO AU11C CM CD H . X co CO •«J-o 600 i r—n 1 1 1—-i 1—t 700 T" BOO FINENESS l 1 1 r soo i 1 1 r IO h CD X co Figure 7e: L i l l o o e t (Rimmed) 1000 o o CO AU. 11U A A + + + + + + ++. 1— 1 1 r 600 700 "i n — i r 600 FINENESS l — ~ i r i i 900 +++ \+ t i • < co to CM CD U3 a a Figure 7f: L i l l o e t (Unrimmed) a a 1000 A A A A 600 AU12 + + + + + + i 1 1 r •~T~ 700 i—i—i 1 — r 800 FINENESS i r ~ i — 300 i r m I- CD X 'a *3 a o Figure 8b: Lower Bridge 1000 00 A A AAA A M i — „ ID AU12 CM ID U CO a" (Nl + + + + + 6 0 0 + + + 7DD T •4, + + + + 1-T 1— r\ " ' l • I' BOO FINENESS ~ i — goo CM ZD CJ CD 'a co 'a a CM Figure 8c: Lower Bridge IDo'o CO to (N CD H X CD a to a ' a ' + + St AU12 T 1 — I 1 1 1 1 1 1 1 1—1 1 1 1 1 1— 0.0 0.2 0.4 0.6 0.B 1.0 1.2 1.4 1.6 to I- CD X CD to ' O ' o CM o 1 .8 Figure 8d: Lower Bridge A CO AU13 CN) LO X co CN! a " o a , + + 600 i r ~ r — 700 i r i r BOO FINENESS 1 r 900 "i r + + ± 1—r |+» -H CO CO X co a a Figure 9b: Bridge-Yalakom Junction o o 1000 00 A A* A* Ar-_; CO AU13 ZD to o * IN + + 600 700 n — i 1 — r BOO FINENESS -r— 900 co CM ZD CJ CO "a "a Figure 9c: Bridge-Yalakom Junction a C3 1000 A 10 CN s H (0 a ' CN AU13 + a I •—1 1 1 1 1 1 0.0 0.2 0.4 a.6 -1 1 r~ 0.B 1.0 CUZ ~ i — 1.2 - | r 1.4 CD CM h CD X co ' o CM Figure 9<J: Bridge-Yalakom Junction " i r 1.6 1.8 A AAAA A/Nt 4MNbVvv\ A 10 AU14 (Nl LO co o" + + + T 1 1 r 600 - 1 — 700 n 1 1 r T 600 FINENESS 1—T I— 900 i 1 1 r + + to (Nl LO X to a Figure 10b Yalakom a o 1000 CD CO AU14 CM ZD CM o + i r 600 1 1 r — 700 + „ v i + -H-+ + + 1 * 1 * 1 1 1 1— T 800 FINENESS - 1 -900 CD (a CM ZD CJ 10 a Figure 10c ™. Yalakom 1000 03 to (Ni CO a ' a" CM AU14 CO CM CD X ID a 1 n 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 Figure lOd Yalakom •AIM CO 600 AU15 t ++ ++ + 4. + i 1 1 1 r 700 n — r — r 800 FINENESS i r + A + , * ; \ i—i—t—t—i—1-+ CO CO CO X CO "o Figure l i b 900 1000 A A A A M AA IO AU15 (0 IN CM 3^ eo ZD U co CO " a CM CM Figure 11c Relay •tff 1**.% t< 44^ 600 700 r 800 FINENESS 900 1000 CO IN co H X eo IO rr a' AU15 + f y i • i IO CM CO X CO ' o " O CM O i — i 1 1 1 1 1 1 1 1 1 1 1 1 r 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 CUZ 1 . 8 Figure l i d : Relay CO CO CM CD H co o " AU18 n 1 1 1 1 1 1—"i 1 1 1 1 1 I ** i 1 i — 1 1 " i "—r 6 0 0 700 BOO 900 FINENESS CO CO CM CD X co " o |- Figure 12b: CM Bassford o 1000 CO to ZD CJ to o " a' OJ a o a " AU18 + + 4 +++ i i r— i r*—i i — i — i r — i — i — r n — " n •— 600 700 BOO 900 FINENESS CO CO CNi U CO " o "a Figure 12 Bassford CO to CM CO x to a' CM AU18 "i 1 — i 1 1 1 1—n 1 1 r — i r — i r~ 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 co CO X co ' o XT ' o CM Figure 12d Bassford o CD i.a AU19 CM CD X co CM — i 1 1 i — t — i ) r — r — i ' y 6 0 0 700 800 FINENESS CM o Figure 13b CM Lightening GO AU19 t t -1 1 1 1 1 1 1 1 — p — i — n r 600 700 .800 FINENESS + + + + + 900 1 CO CO ZD U "o Figure 13c: OJ Lightening 1000 ts) so IO IN CO x to IN AU19 i—I—r- I I I 1 1 1 1 1 1 1 1 1 r— 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 cu; to CM C O X to o CNI o Figure 13d Lightening i a A A to fM AU33 i 1 1 1 r — i 1 1 — i 1 1 1 r 600 700 BOO FINENESS Figure 14b: King Curve - 1 -900 o 1000 03 CM C J co o " AU33 1 1 r—1 1 — I 1 1 1 1—*-r»—r*—r 600 700 600 FINENESS to Figure 14c King Curve 03 AU33 — i — i — i — i — i — i — 0.0 0.2 0.4 0.6 to CM CO to o ~i i i — i 1— i i r— i i — 0.8 1.0 1.2 1.4 1.6 1.8 CUZ Figure 14d King Curve OQ to (Nl co a ' A U 3 4 + + + i 1 1 1 1 1 1 1 1 1 1—n r 600 700 800 FINENESS 03 to (Nl CO a Figure 15b Alhambra 00 AU34 — i — i 1 — i — i — i — i — i — i 1—|r+-n—r 600 700 BOO FINENESS 00 ZD (_) Figure 15c; Alhambra 900 a a 1000 LO 03 (O (Nl CO X AU34 03 to CM CO X I I I I I I—I—I 1— I — I — I — I — I 1—I 1 — 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 cu; Figure 15d Alhambra 3 FINENESS AU37 'BOD T — i — i — r 1 1 +'+4>+- '+ a uoo Figure 16a 851 GO CO CM LO X 600 AU37 4 i—i 1—r ~ i — 100 i 1 1 r BOO FINENESS i — i — i — r i— 300 i 1 1 r CD to CM LO to ' a a CM a Figure 16b: 851 1000 CD CO A U 3 7 CM 3 CJ C M o" —i 1 1 1 1 r 600 700 M 1 ' V* I BOO FINENESS i r 1 r— 900 "i 1 1 r CO IO CM 3 C J to 'o Figure 16c: L'V 851 1000 to CTl 03 AU37 -1 1 1 1 r 0.0 0.2 0.4 03 to CM CO X to o ~i i 1 i i i r — i — i — n i 1 — 0.6 0.8 1.0 1.2 1.4 1.6 1.8 cu; Figure 16d 851 CO CO CM CD X co o " CM AU38 + —I 1 1 1 1 1 1 1 1 1 1 — T 600 700 BOO FINENESS CO CO CM CD X CO " o " o Figure 17b: CM Pioneer M i l l CO AU38 — i 1 r — i 1—i 1 1 — i 1 * i l +*r— i—=*. 1— 600 700 800 900 FINENESS i r CO CO CM ZD CJ CD o co ' a " a CM Figure 17c: Pioneer M i l l I O O ' O O CD -1* IN CO X IO a' IT* AU38 i 1 1—~i 1 1 1 1 1 1 1 — i 1 1 1 1 r 0.0 0.2 0 .4 0.6 0.8 1.0 1.2 1.4 l.E CU* »-«. CO X to ' o Figure 17d: .•V. Pioneer M i l l A M A + 10 AU40 + + 4 4 4 4 4t.-H . 4 ^ i 1 1 1 1 1 1 1 1 1 1 + 1 ' — r ^ n r 600 700 800 900 FINENESS CM h CD X CD "o ' a Figure 18b: Bralorne M i l l 00 AU40 — i — i — i — i — i — i — i — i — i — i " r * 600 700 800 FINENESS Figure 18c: Bralorne M i l l CD IO IN CD H X to a a CN + AU40 — i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r 0 .0 0 .2 0.4 0 . 6 0 .B 1.0 1.2 1.4 1.6 CU* to INI CD X CO o o Figure 18d: CM • Bralorne M i l l 00 CN CO CN AU42 A A + + + + + + + + + + ;+++* • 4- + * 4-— i 1 1 1 1 — i 1 1 — i r " — t — r — T ^ n — » n — t — i r 600 700 BOO 900 FINENESS Figure 19b: Cadwallader CO CM ZD CJ co CM AU42 i 1 1 — r -600 700 800 900 FINENESS CO CM Figure 19c: Cadwallader OQ -1* to (Nl •a • i j -to tl AU42 T i 1 1 f 1 1 1 1 1 1 1 r 1 —i 1 1 r 0.0 0.2 0.4 0.6 0.B 1.0 1.2 1.4 1.6 cuz co to CM XT O Figure 19d: Cadwallader IO AU43 . IM CD + + + + * + +# +- * + X + +-H-+ + + ~ i — i — i — i — i — i — r * — i — i — i 1 1 1—*r 600 700 800 FINENESS - i 1 1 1 1 — T o 900 1000 IP CD 3Z Figure 20b ™ Yale CO CO AU43 CN ZD U co CN a 600 700 800 900 FINENESS A Figure 20c Yale 09 IO I CM CD H X (0 o' I N I*- + AU43 - 1 1 r o.o 0.2 ~1 1 r — 0.4 O.E - i 1 1 r 0.8 1.0 cu; H 1 1— 1.2 1.4 CD IO CM CD X co ' o ' o CM F i g u r e 20d Y a l e a-1.6 i .a A A A A A A UP AU45 IN DO ID IN o" + + + + + + . i r 600 i 1 1 — r 700 - i 1 — + • i 1 t, t f * t + 800 900 FINENESS CO CM H CD X cn co 'a "o CM Figure 21b: Upper Bridge 1000 A CO A A A AA MAAAj - _ 600 AU45 4 4 i r - T -700 4 4 + + 4 ^ M 4, +4 +. +. 44 ± 4*»4 4 f ^ » V 4,+4 4  4 I f I' ' I 1 1* 1 1 1 -FINENESS i 1*—i 1 1 r 900 co CM U co " a CM Figure 21c: Upper Bridge 1000 tn CT i 00 IO IN co X IO + + 4-4-4-4-AU45 IN J * * -O I + s* * *++++ I ' I 4 I r — 0.0 0.2 0.4 0.6 I 1 r -0.8 1.0 cu; ID IM co X to o CM Figure 21d: Upper Bridge ~1 1 1 1 1 1 — 1.2 1.4 1.6 1.8 A A A ' 4 CO CM L D X co o " CM AU48 + + + 4 u • + 4 4 i 1 1 1 1 1 1 1 1 1 1 1 1 1 r 1 — H ^ F — i 1 600 700 BOO 900 FINENESS CO CD X CO ' a "a Figure 22b: .™ St i r r u p a M 1000 °J CO CM CJ co o" to M" o CM AU48 ^ t t T 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 600 700 800 300 FINENESS CO =3 CJ CO ' a "a CM Figure 22c Sti r r u p a a A AAA + 10 CN W. CD H X ca 1 0 a o CN AU48 o.o 1*—r 0.2 ~i r 0.4 • .6 - 1 1 r~ 0.8 1.0 CUZ ~i r 1.2 - 1 r 1.4 1.6 CD CO co CD X CO o o Figure 22c Sti r r u p o o 8 A A A co CN CD H X to a' C M o AU50 + 4 4 + 4 4 4 4 4 4 4 4 4 4 4 + + + t + + + 4 + + + *~n 1 1 1 ' V * I* " l " I M + *| * i 1—*i 4 i »'V^  600 700 BOO 900 FINENESS CD CO CN CD X to 'a Figure 23b: C M Upper Fraser 4 2 1000 CO A U 5 0 CM ZD CD • +1 • rt-t-600 TOO ++ + +* CO CM h 3 C O a a Figure 23c: Upper Fraser BOO FINENESS 900 q 1000 a to AU50 fM CD X IP ci' a ' 0.0 10 CD co a rt a Figure 23d: Upper Fraser ~ ~ l 1 1 T 1 1 1 1—~1 1 1 1 1 1 1 1— 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 c u ; AU50C i 1 1 r 600 700 i—nr + 4 4- + i — n — . I i — r 800 FINENESS I r 900 1 I ' *T CN) CD o [ ~ C D Figure 23e: Upper Fraser a (Rimmed) 1000 A A CO co o" 10 o AU50U < O < +- + 1 1 r 600 t + I 1 1 i ' i 700 I +1* I-600 FINENESS ~1 4 I " Y ^ M 4 T-+^T ca h CO X ta a a a Figure 23f: f- Upper Fraser o (Unrinuned) 900 1000 noo Figure 24a: Big Bar as co to AU51 CM CO + + i—i—r*—i—r*—i—i—r to CM CO co • Figure 24b I C M ' Big Bar 600 700 800 FINENESS i 1 1 1 1 r 900 1000 10 AU51 CN 1-600 -1 r ~ i — 700 800 FINENESS 4 V — r n — r 900 T— i r — r CQ 10 IN ro C_J to a Figure 24c: Big Bar 1000 o 03 U3 3 H GO o" + + + + | " AU51 U3 (M CO I N 'a —i r™*n 1 1 1 1 1 1 1 1 1 1 1 1 r 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 cu; 1.8 Figure 24d Big Bar AU51C 600 1—-V + + + "i 1 r*~ 700 "i r i BOO FINENESS l — n 1 r 900 i 1 r CO CO CM CD co o to o 1000 Figure 24e: Big Bar (Rimmed) GO AU51U + + "i i 1 r*—i 1 1—ii 1 1 r»— 600 700 BOO FINENESS Figure 24f: Big Bar (Unrimmed) AU52 A A A A A A to AU52 IN CD 1 + + 4- + 4 + + . ++ + + ++ + + . + +>+ + T 1—T1—i 'i» " f ' » 1 ' i — h r^H-o BOO 900 1000 4-+ T 1 1 1—*r 600 700 to IN CD 03 'a Figure 25b: Fountain Bar B  FINENESS co A U 5 2 CM 3 H <_> 600 100 + ++ + BOO FINENESS 900 CO CO to o CM o Figure 25c: Fountain Bar 1000 to CM CD X A U 5 2 4 + 4 + + 4 CD I O CM CO 1 0 o Figure 25d: Fountain Bar 0.0 n i i — i — i — i — i — i — i — i — i — i — i — i — i — i — r 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.1 C U Z A A A A A A U 5 2 C 4 4 4 + 4 + 4 •+ 4 + 4 + H 4 4 n n—i i—h 1 r 700 i h—t-t ~i r ~ — r — 7 BOO FINENESS 4 4 I 900 T—i 1 r to (Nl »-< CD 03 a to a a \_™. Figure 25e: a Fountain Bar „ (Rimmed) 1000 CO LO AU52U to CD 4 + CM 1 1 1 I 600 ~ i — r 700 i 1 r i r BOO FINENESS + + 4 300 + + ++ i r •+-H-00 LO CM CD CD O CO 'a 'o a Figure 25f: Fountain Bar (Unrimmed) 1000 •^1 CO to AU52R CO CM a ~~i 1 1 1 — i r — i 1 1 1 r 600 700 600 FINENESS A "i 1 r 900 i r to CM h CO CM a a C3 Figure 26b: Fountain Rim 1000 o o CO AU52R ~~i i i i i i 1 1 1 1 r 600 700 800 FINENESS Figure 26c: Fountain Rim to CO AU52R CO to CM CO to 'a 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0.0 0.2 0.4 0.6 0.6 1.0 1.2 1.4 1.6 1.8 cu; Figure 26d: Fountain Rim AU59 CM CD i s o" i i — i i 1— * \— t * * * ' i 1 — i — f 600 TOO 800 900 FINENESS to Figure 27b - 2 ! Nelson (0 CM C_) (0 a AU59 T I I I I I I I I '* «*.| * t * I * 600 700 800 FINENESS co CM Figure 27c: Nelson 900 1000 oo CT> AU59 i 1 1—I 1 1 1 1 1 r — r 0.0 0.2 0.4 0.6 0.8 1.0 CUJ (0 I N CD Figure 27d Nelson - | 1 1 1 1 1— 1.2 1.4 1.6 1.8 to CM CO AU60 —i 1 1 1—i—1 1*—i—i 1 1 r 600 TOO BOO FINENESS CD to CO to + + Figure 28b ™ Sovereign 1 H I « " r — I — r 900 1000 to AU60 (M to • *** **** ~~i i i i i i — P — i — i 1 — i — i — i — i — i r 600 700 800 900 FINENESS so ta a Figure 28c: Soverei an C M I 1000 £ 03 AU60 T 1 1 1 1— 0.0 0.2 0.4 0.6 co to CM LO X to o ~1 1 1 1 1 1 1 1 1 1 0.8 1.0 1.2 1.4 1.6 1.8 cu; F i g u r e 28d S o v e r e i gn A LO CN 3 . CO CM Q < AU75 600 i — i — i — i — n — r * - ^ T — h — r TOO T 800 FINENESS — 1 — T 4 + + H 1 I t I 1 H r 7 900 r — n — n r 4 LO CD Figure 29b: , M Hope a 1000 OJ CO CO AU75 CM ZD C J CM o i »i > > * « I — > — i — i i* * i 600 700 BOO FINENESS + 4.+ * — i 1 r 900 co CM ZD C J to a Figure 29c: C M Hope a a C 3 1000 vo CD CD CM CD H X oo a" to a" + 4 4 4 AU75 CO CM CD ID a CM a 1 I I 1 1 1 1 1 1 1 1 1 1 1 l i e 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 CUZ Figure 29d: Hope VO on OQ LO CD co a < AU75C i 1 1 r + + 600 700 r 1 — n — n — r T 800 FINENESS l 1—n r 900 i 1 1 r LO CM C D to ' a ' a C M a Figure 29e: Hope (Rimmed) 1000 VO A ID AU75U 1 1 T + 600 i—n 1 r 700 i—i 1 r 600 FINENESS i 1 r 900 ** ii H—h to CN h CO X to o Figure 29f: Hope (Unrimmed) a a 1000 

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