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UBC Theses and Dissertations

A study of barium minerals from the Yukon Territory Montgomery, Joseph Hilton 1960

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A STUDY OP BARIUM MINERALS PROM THE YUKON TERRITORY by JOSEPH HILTON MONTGOMERY B.Sc,  U n i v e r s i t y o f B r i t i s h Columbia,  19^9  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  i n the Department of Geology  We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , I960  In presenting the  this  r e q u i r e m e n t s f o r an  thesis in partial  advanced degree a t the  of B r i t i s h Columbia, I agree that it  freely  agree that for  available  the  f o r r e f e r e n c e and  permission f o r extensive  s c h o l a r l y p u r p o s e s may  D e p a r t m e n t o r by  be  gain  s h a l l not  a l l o w e d w i t h o u t my  GEOLOGY  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, C a n a d a . Date  APRIL 13,  Columbia,  I960,  study.  I  copying of  his representatives.  copying or p u b l i c a t i o n of t h i s  Department o f  shall  the  of  University  Library  g r a n t e d by  that  be  fulfilment  make  further this  Head o f  thesis my  I t i s understood  thesis for written  financial  permission.  i  ABSTRACT  A study o f r a r e barium m i n e r a l s from the Yukon T e r r i t o r y has r e s u l t e d i n the d i s c o v e r y o f a t l e a s t one and p o s s i b l y f i v e new s p e c i e s .  The p r e s e n t  i n v e s t i g a t i o n i s concerned w i t h one o f these, a bariumc a l c i u m - i r o n - a l u m i n o - s i l i c a t e , which i s t e n t a t i v e l y c l a s s e d as an I n o s i l i c a t e and named k e e l e i t e . o p t i c a l and p h y s i c a l p r o p e r t i e s , a chemical  The  analysis,  and the c a l c u l a t i o n of i t s formula are p r e s e n t e d . m i n e r a l has a l s o been s u c c e s s f u l l y s y n t h e s i z e d . X-ray  The An  study o f some supergene and a l t e r a t i o n products  p r e s e n t i n the r o c k s r e v e a l e d the presence  o f an i n t e r -  e s t i n g mixture  salts,  o f barium-calcium  carbonate  s i m i l a r to those obtained as l a b o r a t o r y p r o d u c t s . paragenesis Is a l s o p r e s e n t e d .  A  ii TABLE OF CONTENTS Acknowledgments  ,v  Introduction  1  R e g i o n a l Geology . . . M i n e r a l i z e d Zones Petrograph D e s c r i p t i o n o f the Quartz Monzonite.  2 3 i|  Keeleite . 5> Occurrence f? Physical Properties . . . . . . . . . . . . $ Optical Properties • . . . . . . 6 Chemical A n a l y s i s and C a l c u l a t i o n of Formula 7 Synthesis of K e e l e i t e . 1 1 A l t e r a t i o n Products o f K e e l e i t e 20 Associated Minerals .. 31 Faragenesis . . . . . . . «^2 Conclusions  i|7  Bibliography  . . . . . . . . . .  . . . . . . . .  1*9  ILLUSTRATIONS Figure 1 .  Optic O r i e n t a t i o n o f K e e l e i t e  2.  Possible Optic O r i e n t a t i o n of  Figure  . . . .  22  Mineral C Table 1 . Table 2. Table 3 «  Table I4.  Spectrographic Keeleite  1  Analysis of 8  Chemical A n a l y s i s and C a l c u l a t i o n of Formula f o r K e e l e i t e .  9  X-ray Data f o r N a t u r a l K e e l e i t e , Fused-Annealed K e e l e i t e , and Synthetic Keeleite R e v i s e d C a l c u l a t i o n of K e e l e i t e Formula . . . . . . . . . . . .  l£ .  .  .  1  7  iii  Table 5»  Comparison of Oxide Percentages i n the Two C a l c u l a t e d Formulas . . .  18  Table 6»  X-ray D a t a f o r B a ^ F e ^ F e ^ S i O ^ J l O * . 19  Table 7 .  X-ray Data f o r M i n e r a l C . . . . . .  22  Table 8 .  S p e c t r o g r a p h s A n a l y s i s of Mineral C  23  Table 9 .  S p e c t r o g r a p h s A n a l y s i s of Mineral E  2$  Table 10.  X-ray Data f o r M i n e r a l E  26  Table 1 1 .  Comparison of X-ray Data o f White Goating, S y n t h e t i c B a r y t o c a l c i t e , and S y n t h e t i c A l s t o n i t e . . 2 9  Table 12.  S p e c t r o g r a p h i c A n a l y s i s of T a r a m e l l i t e (Ross R i v e r , Y.T.)  . . .  33  Table 1 3 .  X-ray Data f o r T a r a m e l l i t e  3k  Table  Chemical A n a l y s i s of Taram e l l i t e and C a l c u l a t i o n of i t s Formula  36  Table 1$,  X-ray D a t a f o r G i l l e s p i t e  38  Table 16.  Spectrographic A n a l y s i s of Gillespite  39  Table 1 7 .  Spectrographic A n a l y s i s of Sanbornite  I4O  Table 18.  X-ray D a t a f o r Sanbornite  I4I  Plate I.  Laths o f K e e l e i t e ( c r o s s e d nicols)  Plate I I .  . . . . . l l i -  X-ray Powder Photographs of Keeleite . . . . . . . . . . . . . . .  16  P l a t e I I I . X-ray Powder Photograph o f the Compound, 5Ba0.2FeO.FegO^.lOSiOg Plate IV.  Mineral  Plate  X-ray Powder Photograph o f  V.  Mineral Plate VI.  C, g l l l e s p i t e ,  keeleite  C  M i n e r a l E and k e e l e i t e  P l a t e V I I . M i n e r a l E and sanbornite  . . . .  P l a t e V I I I . X-ray Powder Photographs o f Mineral E . P l a t e IX. X-ray Powder Photographs o f Barium-Calcium Carbonates . . . P l a t e X. Taramellite . . Plate XI.  X-ray Powder Photographs of Taramellite  .  P l a t e X I I . G l l l e s p i t e , K e e l e i t e , and ' Taramellite . . . . . . . . . . P l a t e XIII.  X-ray Powder Photographs of Sanbornite  Map 1.  Key map showing l o c a t i o n o f mineral deposit . . . . . .  Map 2.  Map o f r e g i o n a l geology  • .  V  ACKNOWLEDGMENTS I am g r e a t l y Indebted t o Dr. R.M. Thompson o f the U n i v e r s i t y of B r i t i s h Columbia f o r h i s many sugg e s t i o n s and guidance throughout the course  of t h i s work.  I would a l s o l i k e to thank the Department o f Mining  and M e t a l l u r g y f o r the l o a n o f equipment neces-  s a r y f o r the s y n t h e s i s o f k e e l e i t e , and the s t a f f members of that department, a l l o f whom o f f e r e d t h e i r  willing  co-operation. I n a d d i t i o n , I would l i k e to express  my  g r a t i t u d e t o Dr. K.C. McTaggart o f the U n i v e r s i t y of B r i t i s h Columbia f o r p r o o f - r e a d i n g the f i r s t f o r h i s many h e l p f u l  d r a f t , and  suggestions.  I would l i k e t o thank Dr. R.E. D e l a v a u l t of the U n i v e r s i t y o f B r i t i s h Columbia f o r p r e p a r i n g the f e r r o u s oxide used i n the s y n t h e s i s of k e e l e i t e , and f o r h i s generous help during the course this  of preparing  thesis. I would a l s o l i k e  t o thank Dr.  J.O. Wheeler  and D r . J.A. Roddick of the G e o l o g i c a l Survey o f Canada, Mr.  S. Sandner, Mr. Pat C l a y , and the Newmont  Mining  C o r p o r a t i o n of Canada f o r t h e i r v a r i o u s a s s i s t a n c e s . I am al so indebted to the Royal Museum f o r the l o a n of type  Ontario  specimens f o r comparison.  M A P INCH  =  2 MILES  4  GRANITIC  STOCKS  METASEDIMENTS DRIFT  COVERED  KEELEITE  <  1  INTRODUCTION The purpose of t h i s i n v e s t i g a t i o n i s t o desc r i b e a new barium m i n e r a l , k e e l e i t e , which occurs i n a c o n t a c t metasomatic  d e p o s i t i n the Yukon T e r r i t o r y .  The m i n e r a l d e p o s i t i s l o c a t e d on the Sheldon Lake Sheet (Map 1 0 £ J ) near the head-waters  of Ross R i v e r and about  two m i l e s southwest o f G i l l e s p i t e Lake on the Gun group of c l a i m s .  These claims were staked for t h e i r z i n c con-  tent f o r the Newmont Mining C o r p o r a t i o n o f Vancouver, B.C.  i n 1957*  Map  1  shows the g e n e r a l l o c a t i o n o f the  d e p o s i t and Map 2 i t s exact l o c a t i o n and r e g i o n a l geology. Previous g e o l o g i c a l work i n the area c o n s i s t s only o f s e v e r a l r e c o n n a i s s a n c e o p e r a t i o n s .  Joseph Keele^"  explored the Upper P e l l y and Ross R i v e r s i n 1 9 0 7 and 1 9 0 8 . No f u r t h e r work was done u n t i l 19kk when E.D. K i n d l e made a g e o l o g i c a l r e c o n n a i s s a n c e a l o n g the Canol Road. 1958,  J.A. Roddick and J.O. Wheeler  In  of the G e o l o g i c a l  Survey o f Canada i n i t i a t e d " O p e r a t i o n P e l l y " , a g e o l o g i c a l reconnaissance which i n c l u d e s the Sheldon Lake sheet. I t was w h i l e I n the employ o f the G e o l o g i c a l Survey o f Canada during the 1 9 5 8 f i e l d season that the author c o l l e c t e d the specimens on which the p r e s e n t work i s based. The present i n v e s t i g a t i o n was suggested by Dr. R.M. Thompson o f the U n i v e r s i t y of B r i t i s h Columbia, who identified gillespite  ( B a P e S i ^ 0 ) i n a specimen sub1 0  2 m i t t e d by Mr. in  S c o t t y A l a n of Newmont Mining  Corporation  1957The  l a b o r a t o r y work was  of B r i t i s h Columbia i n 1959  and  done at the U n i v e r s i t y  I960.  REGIONAL GEOLOGY The  area, as shown i n Map  2, i s c h a r a c t e r i z e d  by s e v e r a l i n t r u s i v e stocks which vary I n composition g r a n o d i o r i t e to g r a n i t e .  from  At the c o n t a c t s of these Igneous  bodies, the metasediments, which c o n s i s t o f a r g i l l i t e s , s h a l e s , s l a t e s , q u a r t z i t e s , and limestone, have been conv e r t e d to h o r n f e l s e s and  skarns.  Many m i n e r a l i z e d zones  have been r e p o r t e d a s s o c i a t e d w i t h some of these stocks.  granitic  Most of them are simply p y r r h o t i t e Impregnations  of the t h e r m a l l y metamorphosed r o c k s , but values i n g o l d , s i l v e r , copper and z i n c have been obtained i n a The  few.  c o n t a c t aureole from which the present  of specimens was  c o l l e c t e d surrounds  a q u a r t z monzonite  s t o c k which i s exposed over an area of approximately square m i l e s . the e a s t , and almost  The  to 85  degrees.  and has an apparent  i  is  The c o n t a c t on the n o r t h and west s i d e s  o f the s t o c k d i p s outward from the stock at an angle 80  five  i n t r u d e d rocks are s t e e p l y d i p p i n g to  along the western c o n t a c t , the bedding  vertical.  suite  The  of  c o n t a c t aureole i s r e l a t i v e l y narrow  width of 50  to 75  feet.  3 M i n e r a l i z e d Zones The m i n e r a l i z e d zones are lens^e-shaped and concordant w i t h the bedding  i n the metamorphic r o c k s ,  and are p r o b a b l y d e r i v e d from l o c a l l i m e - r i c h b o d i e s . Two main outcrops o f the skarn zone were examined. The f i r s t  outcrop i s a t an e l e v a t i o n o f 5>,1{00  f e e t and i s exposed on the west w a l l o f a small c i r q u e . I t Is a concordant  body (0°/60°E) and c o n s i s t s  essentially  o f f i n e t o medium-grained w i t h e r i t e , s a n b o r n i t e , and hedenbergite.  The l e n s ^ i s about 200 f e e t l o n g and 30  f e e t t h i c k at i t s t h i c k e s t p o i n t .  The r o c k on the hanging  w a l l c o n s i s t s o f s l a t e , and on the f o o t w a l l o f s l a t e and quartzite.  Compositional banding  i s prominent i n the  l e n s e , w i t h i n d i v i d u a l bands v a r y i n g from l / 2 t o 2 inches i n t h i c k n e s s and composed o f v a r y i n g c o n c e n t r a t i o n s o f s a n b o r n i t e , w i t h e r i t e , and hedenbergite. The  other m i n e r a l i z e d zone Is i n the c i r q u e  f l o o r and i s exposed l a r g e l y by open p i t s which were excavated by Newmont Mining C o r p o r a t i o n .  T h i s body shows  no d e f i n i t e a t t i t u d e , but i n some p l a c e s , appears flat-lying.  almost  I t c o n s i s t s mostly of f i n e to medium-grained  skarn which c o n t a i n s hedenbergite, g l l l e s p i t e ,  keeleite,  t a r a m e l l i t e , and other s i l i c a t e s p l u s s m a l l amounts o f s p h a l e r i t e , c h a l c o p y r i t e , and p y r r h o t i t e .  k F e t r o g r a p h i c D e s c r i p t i o n of the Quartz Monzonite In hand specimens, the quartz monzonite i s l e u c o c r a t i c , medium-grained p h a n e r i t i c , homophanous, and very s l i g h t l y In  porphyritic.  t h i n section, plagioclase, orthoclase,  quartz, b i o t i t e , c h l o r i t e , and accessory a p a t i t e are evident.  The p l a g i o c l a s e Is almost  c a s i o n a l l y twinned  a l l zoned, and oc-  ( C a r l s b a d and A l b i t e t w i n n i n g ) .  The  zoning i s normal and covers a r a t h e r wide range, v a r y i n g from c a l c i c l a b r a d o r I t e (  ( A n ^ ) i n the cores t o o l i g o c l a s e  An£Q) on the o u t s i d e .  anhedral c r y s t a l s  O r t h o c l a s e i s p r e s e n t as l a r g e  (f>mra.) o f a s l i g h t l y p o r p h y r i t i c  nature,  and which c o n t a i n many i n c l u s i o n s of s m a l l p l a g i o c l a s e c r y s t a l s and b i o t i t e fragments. partially sericitized.  Quartz  Both f e l d s p a r s have been occurs as anhedral g r a i n s  i n t e r s t i t i a l t o the f e l d s p a r s , and c o n t a i n s i n c l u s i o n s of p l a g i o c l a s e and b i o t i t e .  A s m a l l amount of b i o t i t e  occurs as subhedral c r y s t a l s which have been s l i g h t l y chloritized.  A p a t i t e , the only accessory m i n e r a l  i s p r e s e n t as minute euhedral  found,  crystals.  Mode: Plagioclase Orthoclase Quartz Biotite Chlorite Apatite  -  30% 30% 30% 8% 2% present.  The wide range of zoning i n the p l a g i o c l a s e i s i n d i c a t i v e o f a v e r y r a p i d change i n temperature pressure•  and/or  5  KEELEITE Keeleite  (pronounced  of Joseph Keele, a former  k e e l - i t e ) i s named i n memory  o f f i c e r o f the G e o l o g i c a l Survey  of Canada who made a g e o l o g i c a l reconnaissance  from Ross  R i v e r Post t o the MacKenzie R i v e r i n 1907-1908. Occurrence; Keeleite (Ba^Ca^e^-Pe,'Al^(SiO^)]^)  i s found  i n a c o n t a c t metasomatic d e p o s i t adjacent t o a p o r p h y r i t i c q u a r t z monzonite s t o c k .  I t occurs as a massive,  l i n e c o n s t i t u e n t o f skarns which have developed limestone bodies adjacent t o the igneous  T i ( S I ^ 0 ) (OH)^, g i l l e s p i t e l 2  i n original  contact.  m i n e r a l assemblage i n c l u d e s k e e l e i t e , b a r i t e , quartz, andradite, t a r a m e l l i t e  crystal-  The  hedenbergite,  ( (Ba,Ca,Na)lj. (Fe',Mg) Pe'2  ( B a P e S i i | 0 ) , sanbornite 10  (BaSi20cj), c h a l c o p y r i t e , w i t h e r i t e , double carbonate  salts  o f barium and c a l c i u m , and f o u r other m i n e r a l s which may be new s p e c i e s . Physical Properties; In hand specimen, k e e l e i t e i s massive,  crystal-  l i n e , and i n t i m a t e l y mixed w i t h i t s a s s o c i a t e d m i n e r a l s and a l t e r a t i o n p r o d u c t s .  I t possesses  three p o o r l y d e v e l -  oped cleavages which are u s u a l l y evident only i n t h i n section. hardness  The m i n e r a l i s c o l o r l e s s to p a l e yellow, has a of 6,  a s p e c i f i c g r a v i t y o f 3*5>1, and fuses a t 3  to a weakly magnetic bead.  I t possesses  a vitreous lustre  6 and c o n c h o i d a l f r a c t u r e  very s i m i l a r t o t h a t o f q u a r t z .  The a l t e r a t i o n products of k e e l e i t e i n c l u d e a f i b r o u s b l u e pleochroic mineral, a s e r i c i t i c mineral, a pale yellow fibrous pleochroic mineral, a yellow i s o t r o p i c mineral, and a yellow-brown m i n e r a l .  These m i n e r a l s a l s o r e s u l t  from the a l t e r a t i o n of g l l l e s p i t e or s a n b o r n i t e and are more f u l l y d e s c r i b e d i n the s e c t i o n on a l t e r a t i o n p r o d u c t s . Specimens which were c o l l e c t e d from the s u r f a c e are coated w i t h a y e l l o w , e a r t h y m a t e r i a l and a white c r u s t of bariumc a l c i u m carbonate  s a l t s and o p a l .  Optical Properties: The determined  i n d i c e s of r e f r a c t i o n o f k e e l e i t e were  w i t h immersion o i l s and the o p t i c a l  t i o n by the u n i v e r s a l stage method.  orienta-  The values g i v e n f o r  the o p t i c angle and cleavage angles were c o r r e c t e d u s i n g Federow's diagram.  The o p t i c a l o r i e n t a t i o n i s r e p r e s e n t e d  i n F i g u r e 1 and the o p t i c a l p r o p e r t i e s are as f o l l o w s : Color  -  colorless i n thin section.  Form and Cleavage - subhedral t o euhedral t a b u l a r c r y s t a l s w i t h two p r i s matic cleavages which make an angle of w i t h each other, and one p i n a c o i d a l cleavage. A l l the c l e a v ages are p o o r l y developed. Indices of R e f r a c t i o n n  n  x  4  Y  Birefringence  = 1.61*3 -  = 1.61*5 *  .003  .003  = 1.61*9 * .003 -  h  z  - n  x  = .006  7  Extinction  - P a r a l l e l to e l o n g a t i o n of crystals.  O r i e n t a t i o n - length, f a s t or l e n g t h slow Because of the t a b u l a r nature of the c r y s t a l s . Twinning  - The t w i n plane i s p a r a l l e l to the e l o n g a t i o n of the c r y s t a l .  Optic Angle and S i g n - the f i g u r e i s b i a x i a l p o s i t i v e w i t h 2V = i | 7 ° . Dispersion  - rhombic, very s t r o n g r y v.  F i g u r e 1.  with  O p t i c O r i e n t a t i o n of K e e l e i t e .  Chemical A n a l y s i s and C a l c u l a t i o n of Formula; K e e l e i t e i s i n t i m a t e l y mixed w i t h i t s a l t e r a t i o n products  and  the m i n e r a l s g i l l e s p i t e , q u a r t z , t a r a m e l l i t e ,  hederibergite, a n d r a d i t e , s u l f i d e m i n e r a l s , I t was  therefore impossible  enough f o r a n a l y s i s .  to f i n d any  and  carbonates.  specimens pure  Consequently, i t was  necessary  to  8 r e s o r t t o g r i n d i n g , s c r e e n i n g , magnetic  s e p a r a t i o n , heavy'  l i q u i d s e p a r a t i o n and f i n a l l y , hand-picking under the b i n o c u l a r microscope. to be  The f o l l o w i n g procedure was  found  satisfactory. Hand specimens which c o n t a i n e d r e l a t i v e l y  large  amounts of k e e l e i t e were crushed to l / i * i n c h s i z e . c l e a n e s t of these fragments o b t a i n a +80  The  were ground and screened to  and -60 mesh f r a c t i o n .  This f r a c t i o n  was  then passed through a Pranz Isodynamic Separator s e t at a 2 5 degree  0.i|25  tilt  and a 1 5 degree c a n t .  An amperage of  removed most of the g l l l e s p i t e , the blue  alteration  product, and the s u l f i d e s w h i l e the k e e l e i t e and mixed g r a i n s remained  behind i n the non-magnetic f r a c t i o n .  The  mixed g r a i n s were removed by hand-picking under the b i n o c u l a r microscope.  A very s m a l l amount of q u a r t z was  moved by g r a v i t y s e p a r a t i o n i n broraoform.  re-  The r e s u l t s of  a s p e c t r o g r a p h i c a n a l y s i s made on a p o r t i o n of the sample are presented i n T a b l e 1 .  Major  Intermediate  Minor  Trace  Ba  Ca  Mg  B  Si  Al  Zn  Be  Pe  Mn  Ti  Na  Zn  Sr  Table 1 .  S p e c t r o g r a p h i c A n a l y s i s of Keeleite.  9  A sample o f k e e l e i t e weighing  about 0 . 8 grams  was submitted f o r chemical a n a l y s i s to H.V* S h a r p i e s , G»S. E l d r i d g e & Go., Vancouver, B.C.  The r e s u l t s appear  i n Table 2 w i t h c a l c u l a t i o n s f o r a chemical f o r m u l a .  Oxide  %  BaO  31*. 16  CaO  6.25  Si0 A  1  2  2 ° 3  PeO *  Corr.$  31*.  33  Mol. Wt. 153.36  Mol.P.  Mol. Ratio  Th.$  .223  6.021  3!*.07 6.23  6.28  56.08  .112  3.021*  1*0.50  1*0.70  60.06  .667  18.009  3.53  3.55  101.91*  .031*8  12.03  71.58  .1665  .0080  11.97  MnO  0.57  0.57  70.90  MgO  1.1*6  1.1+8  1*0.32  .0365  ZnO  1.05  1.06  81.38  .0130  SOr> j  0.91*9  3.77  ) 15.90  76.01*8  -  tr. 99.1*9  1*0.03  100.00  -xTotal i r o n c a l c u l a t e d t o PeO Table 2 .  Chemical A n a l y s i s and C a l c u l a t i o n o f Formula:, f o r K e e l e i t e .  In c a l c u l a t i n g the formula, the f o l l o w i n g procedure was used.  N e g l e c t i n g the t r a c e o f s u l f u r , the  metal oxide percentages were c o r r e c t e d t o b r i n g the t o t a l to 1 0 0 $ . and t h e i r m o l e c u l a r p r o p o r t i o n s c a l c u l a t e d by d i v i d i n g the c o r r e c t e d percentages by t h e i r a p p r o p r i a t e m o l e c u l a r weights.  I t was then necessary t o decide which  elements were s u b s t i t u t i n g f o r others and which were e s s e n t i a l  10 to the c r y s t a l s t r u c t u r e .  Since barium and  s i l i c o n oxides  are the major components, they were c o n s i d e r e d ions.  The  alumina c o u l d have been added to the  aluminum commonly r e p l a c e s tures.  essential  I t was,  silica,  s i l i c o n i n many s i l i c a t e  as  struc-  however, r e t a i n e d as an e s s e n t i a l con-  s t i t u e n t because there  are not  s u f f i c i e n t monovalent  cations  present to compensate f o r the d e f i c i e n c y i n p o s i t i v e charge which would r e s u l t , and  a l s o because the near p e r f e c t b a l -  ance of Si02:BaO = 3 : 1 would be u p s e t .  The  ferrous  z i n c when added  i r o n , manganese, magnesium, and  t o g e t h e r gave a m o l e c u l a r p r o p o r t i o n equivalent silica.  oxides of  of 0 . 2 2 1 * which i s  to t h a t of barium oxide and  one-third  that  High valence manganese might s u b s t i t u t e f o r  aluminum, but would be  a g a i n the balance of m o l e c u l a r  d e s t r o y e d i f MnO  Although the  ionic radius  proportions  were c a l c u l a t e d i n w i t h alumina.  Calcium oxide i s a l s o c o n s i d e r e d  an e s s e n t i a l c o n s t i t u e n t .  of calcium  (0.99)  is sufficiently  s m a l l to enable i t to s u b s t i t u t e f o r barium (1.31+), size difference i s greater  than the \$% l i m i t  accepted f o r i o n s u b s t i t u t i o n . CaOrBaO = 1:2  part f o r ferrous j e c t e d f o r the The  i r o n ( O . 7 I 4 ) , but  3  occupies an e s s e n t i a l  this possibility i s re-  same reasons s t a t e d above. s m a l l e s t near whole numbers are  derived  obtained  are m u l t i p l i e d by  a factor  formula i s thus 6BaO„3Ca0.6FeO.Al 03.  18S102, or i n the more c o n v e n t i o n a l (Si0 )l8.  ratio  Calcium might a l s o s u b s t i t u t e i n  when the m o l e c u l a r p r o p o r t i o n s The  the  generally  Furthermore, the  suggests t h a t c a l c i u m  p o s i t i o n i n the l a t t i c e .  of 2 7 .  of  2  manner - B a ^ C a ^ e ^ A ^  11  Although m i c r o l i t e s o f k e e l e i t e were  obtained  from a mixture of t h i s composition, the formula, B a ^ C a ^ F e ^ A l ^ S i O ^ J l S i s not the c o r r e c t formula. reasons f o r t h i s statement w i l l be d i s c u s s e d  The  fully in  the s e c t i o n on s y n t h e s i s . Synthesis  of K e e l e i t e : In order  t o t e s t the p o s s i b i l i t y o f s y n t h e s i z i n g  k e e l e i t e by d i r e c t f u s i o n o f the c o n s t i t u e n t oxides, the n a t u r a l m i n e r a l was fused  to a g l a s s .  An X-ray powder  photograph o f the f u s e d m a t e r i a l showed that the s t r u c t u r e had been completely destroyed.  The m i n e r a l was then p l a c e d  i n an evacuated s i l i c a tube and annealed a t 850°C f o r 21* hours.  The r e s u l t a n t product was not completely  l i z e d , probably owing t o the r e l a t i v e l y short  crystal-  annealing  p e r i o d , but m i c r o l i t e s i n r a d i a t i n g groups were s c a t t e r e d throughout the g l a s s .  An X-ray powder photograph of t h i s  product proved the c r y s t a l s to be k e e l e i t e . or gaseous c o n s t i t u e n t s The  Thus, no hydrous  are p r e s e n t .  main d i f f i c u l t i e s encountered i n s y n t h e s i z i n g  k e e l e i t e were the i n s t a b i l i t y o f i t s c o n s t i t u e n t the problem o f a s u i t a b l e c o n t a i n e r , maintaining  oxides,  and the n e c e s s i t y o f  a n e u t r a l atmosphere d u r i n g f u s i o n and c r y s t a l -  l i z a t i o n t o prevent the o x i d a t i o n of f e r r o u s i r o n . and  Bowen  Schairer-^ experienced d i f f i c u l t y i n c o n t r o l l i n g and  d e f i n i n g the s t a t e of o x i d a t i o n of i r o n i n t h e i r work on  12 the system PeO - S i 0 . 2  to  They found t h a t even i n vacuums  O.GOOI4 mm. Hg, the f e r r o u s i r o n o x i d i z e d .  A solution  was o b t a i n e d by u s i n g I r o n c r u c i b l e s i n a n i t r o g e n atmosphere.  The i r o n c r u c i b l e s served t o keep the i r o n i n  the f e r r o u s s t a t e , but s m a l l amounts o f i r o n were added to  the melt by r e a c t i o n w i t h the c r u c i b l e .  S c h a i r e r and  Y a g i ^ s u c c e s s f u l l y c r y s t a l l i z e d s i l i c a t e s i n the system PeO-Al203~Si02 by f o l d i n g p i e c e s o f the g l a s s i n i r o n s e a l i n g them i n evacuated temperatures  foil,  s i l i c a tubes, and heating a t  below the s o l i d u s f o r s e v e r a l days or weeks.  S e v e r a l charges  of k e e l e i t e composition were f u s e d i n i r o n  c r u c i b l e s , but without  success.  ^  Barium oxide i s a v a i l a b l e as c h e m i c a l l y pure m a t e r i a l , but i s somewhat hygroscopic and consequently not keep w e l l .  does  Ferrous oxide i s v e r y u n s t a b l e and o x i d i z e s  r a p i d l y to a mixed m a t e r i a l on s t a n d i n g .  The product  used  i n the s y n t h e s i s o f k e e l e i t e was obtained by h e a t i n g f e r r o u s o x a l a t e (FeC^O^.SB^O) under vacuum t o e x p e l the carbon d i o x i d e and water.  The r e t u r n t o atmospheric  p r e s s u r e must  be g r a d u a l t o prevent combustion o f the unstable It  appeared  product.  t o be homogeneous and composed e n t i r e l y o f  b l a c k ferrous oxide.  Since c a l c i u m oxide Is very  hygro-  s c o p i c , c a l c i u m was added i n the form o f CaSiC^ which was made by f u s i n g c a l c i u m carbonate  and s i l i c a .  Alumina and  s i l i c a were e a s i l y obtained i n pure form and o f f e r e d no problem.  13 The c o n t a i n e r s w i t h which the w r i t e r was most s u c c e s s f u l were V i t r e o s i l tubes which were s e a l e d  under  vacuum t o o b t a i n an atmosphere as c l o s e to n e u t r a l as possible. The oxides were weighed out i n a p p r o p r i a t e amounts to make a 10 gram charge.  Only 2 grams were r e -  q u i r e d f o r the f u s i o n , but g r e a t e r accuracy i s obtained by weighing the l a r g e r amounts. i n a mortar and thoroughly mixedr  The oxides were ground The mixture was then  p l a c e d i n a s i l i c a tube and heated g e n t l y under vacuum to  e x p e l any moisture which may have been p i c k e d up d u r i n g  g r i n d i n g and m i x i n g .  The tube and contents were g r a d u a l l y  heated t o a r e d heat, then s e a l e d by m e l t i n g i n an oxygengas flame and t w i s t i n g o f f the end o f the tube.  The  charge was then f u s e d a t 1350°C i n a "Glow-Bar" furnace and kept i n the f u s e d s t a t e f o r one hour.  Some c o r r o s i o n  took p l a c e on the i n s i d e w a l l o f the tube, but a p p a r e n t l y a s m a l l amount o f excess s i l i c a i s not d e t r i m e n t a l t o the f o r m a t i o n of k e e l e i t e .  The s t a b i l i t y  o f k e e l e i t e i n excess  s i l i c a i s suggested by the occurrence together o f k e e l e i t e and quartz i n n a t u r e . of  The tube was then opened.  A piece  the charge, now a s i l i c a t e g l a s s , was chosen from the  c e n t e r of the melt and p l a c e d i n another s i l i c a tube, which was evacuated and heated at 8£0°C f o r 1*8 hours. of  The purpose  the change was t o a l l o w most of the s u r f a c e area o f the  s i l i c a t e g l a s s t o be out o f c o n t a c t w i t h the tube i n order  Ik  to prevent r e a c t i o n during the l o n g p e r i o d o f a n n e a l i n g . The product obtained was a p p a r e n t l y e n t i r e l y and composed of f i n e p r i s m a t i c c r y s t a l s .  crystalline  An X-ray powder  photograph o f t h i s m a t e r i a l proved i t to be k e e l e i t e w i t h a small amount o f contaminating q u a r t z .  A comparison o f  X-ray data f o r s y n t h e t i c k e e l e i t e , n a t u r a l k e e l i t e and and fused, annealed n a t u r a l k e e l e i t e i s presented i n Table 3»  O p t i c a l determinations were not made on the  s y n t h e t i c product because o f i t s extremely f i n e g r a i n , and a s p e c i f i c g r a v i t y d e t e r m i n a t i o n was not made because of t h e p o s s i b l e presence  of undetected g l a s s or f r e e  silica.  Plate I.  Laths of k e e l e i t e (crossed n i c o l s ) .  X7£  15 Table 3 .  Natural  X-ray B a t a f o r N a t u r a l K e e l e i t e , Fused-Annealed K e e l e i t e , and Synthetic Keeleite.  Keeleite  (UBC X2528) d  I  I  -  6.51  k  5- • 3 -  5 . 9-9  1  1**21  2  3.1*5 -  1 2 10  -  -  -  3.88  10  -  10 1 1  -  -  10  3.16 3.00 2.86  i  -  -  -  2.62 2.1*6  7  1 2 2 2  I s  1 3  2.36 2.30  2.21* 2.18 2.11  l 2  2 2 2 3 1 2  2.07  2.02 1.953 1.899 1.831*  -  -  1.778  3  2 2  I.707  3 X  1.535 1.506 1.1*80  3  1.1*33  I.678 1.6l6b  -  2 5  q  Fused-Annealed Natural Keeleite (UBC X2701*)  -  -  -  1  2  -  1  -  2 1 S2  *•"  d —  14.25 5.99  3.90  3.60  3.1*5 3.16  -  2.85  -  2.65  2.147  2.21* 2.37  —  1.838 1.778 1.610 i.5l*o 1.965  1.1*80 mm  p o s s i b l e quartz l i n e s .  Synthetic  Keeleite  (UBC X29i*7) I 1 2 3 3 3  56 -  d  6.51  5.95  1+.65 1*.23  i*.08 3.83 —  10 8  3.30  1  3.03  7  1  1 8 1 2 1 1 1 1 2  -  3  k  2  1 2  1 1 2  2  3 3  1* 2  q  3.1*8  3.16  q  2.92 2.80 2.61 2.I46 2.36 2.31  2.21* 2.19 2.12 2.08 2.02 1.91*9  -  -  1.8l7q 1.781 1.707  I.678 1.631* 1.588 1.537 1.512 1.1*78 1.1*33  P l a t e I I X-ray Powder Photographs o f Keeleite. Top  - K e e l e i t e , Y.T. - UBC Cu/NiO.  X2529  Center - Pused-Annealed K e e l e i t e , Y.T.UBC X 2 7 0 1 * Cu/NlO. Bottom - S y n t h e t i c Cu/NiO. The  K e e l e i t e - UBC X2968  data above show that almost every l i n e on  the X-ray f i l m f o r n a t u r a l k e e l e i t e i s a l s o present f o r the s y n t h e t i c m a t e r i a l .  The e x t r a l i n e s marked (q) are  a t t r i b u t e d t o the presence o f a small The  remaining d i s c r e p a n c i e s  i n spacing  amount o f q u a r t z . and i n t e n s i t i e s  are b e l i e v e d due t o p r e f e r r e d o r i e n t a t i o n o f m i c r o l l t e s i n the s y n t h e t i c m a t e r i a l .  L e v i n and U g r i n i c ^ were con-  f r o n t e d by a s i m i l a r problem i n t h e i r work on the system Ba0-B203-Si0 . 2  They found that X-ray d i f f r a c t i o n data  17 f o r t h e i r s i l i c a t e s v a r i e d b o t h i n the l i n e s p r e s e n t or absent,  and i n t h e i r r e l a t i v e i n t e n s i t i e s .  buted the d i s c r e p a n c i e s to p r e f e r r e d  They  attri-  orientation.  I t was s t a t e d p r e v i o u s l y t h a t , although  crystals  were o b t a i n e d from a melt o f composition Ba^Ca^Fe^AlgCSIO^JlS, that t h i s formula was i n c o r r e c t .  I n the a n a l y s i s g i v e n i n  Table 2,  only t o t a l i r o n was determined  to FeO.  However, a l a t e r sample submitted  and t h a t c a l c u l a t e d to the same  a n a l y s t f o r the d e t e r m i n a t i o n o f f e r r o u s and f e r r i c  iron  showed t h a t 8.32$ FeO and 4.16$ Fe203 are p r e s e n t i n the mineral keeleite.  A new chemical formula was c a l c u l a t e d  on the b a s i s o f these r e s u l t s as shown i n T a b l e 1*. Oxide BaO CaO S102 AI2O3 FepOo FeO MnO MgO ZnO  314.16  6.25 ij0.50 3.53 I|.16 8.32 0.57 1.1+6 1.05  J  Mol.Wt.  Mol. Prop,  Mol.Ratio  153.36  .223 .111 .671+ .035 .026 .116  1+.011+ 1.998 12.132  56.08 60.06 101.91+  159.16 71.58 70.90 1+0.32 81.38  }  1.098  .008  .036 .013  3.111+  tr.  100.00 Table 1+. The  Revised C a l c u l a t i o n of K e e l e i t e Formula.  c a l c u l a t i o n o f the formula was done i n the  same manner as shown i n Table 2, except t h a t Fe203 was added t o AI2O3. molecular r a t i o s .  A f a c t o r o f 18 was used  t o o b t a i n the  The r e s u l t i n g formula i s !+Ba0.2Ca0.  18 3PeO. ( P e A l ) 0 . 1 2 S i 0 2  3  q u e s t i o n of how  or Ba.Ca Pe'»(P8 ,Al) (SiO )12.  k e e l e i t e c r y s t a l s c o u l d be obtained from  the o r i g i n a l formula may the percentages  be answered r e a d i l y by  of oxides c o n t a i n e d I n the two  Oxide  Ba Ca3Pe Al (.SI0 )l8  BaO  34-07 %  6  6  3  2  2  2  3  33.70 6.16 11.80  15.9 3.77  8.7*1  1*0.03  39.59  Fe 0-j  formulas  Ba^C & Fe^ (Pe', A l j ( S i 0 ) 12  6.23  CaO  comparing  5*  as shown I n Table  PeO AloOo  The  f  2  2  SI0  2  Table 5«  Comparison of Oxide Percentages i n the Two C a l c u l a t e d Formulas.  The percentages  of the oxides of barium, c a l c i u m  and s i l i c o n are c l o s e enough i n the two  formulas t o allow  c r y s t a l l i z a t i o n of k e e l e i t e from e i t h e r . between FeO  and  ( A l , F e ) 0 2 i n the two 2  The  formulas  discrepancy indicates  that o x i d a t i o n of the f e r r o u s i r o n must c e r t a i n l y have taken p l a c e to a l l o w the development of k e e l e i t e i n the m e l t .  Any  crystals  oxides i n excess over those r e q u i r e d f o r  the f o r m a t i o n of the compound may  have combined w i t h  silica  and remained i n the g l a s s y s t a t e . In the course of syntheses a d d i t i o n a l compound was 5Ba0.2FeO.Pe 03.10Si0 . 2  2  of k e e l e i t e ,  obtained from the  one  composition  The c r y s t a l s o b t a i n e d were dark  19 brown, p l a t y , and d i s t r i b u t e d  i n coarse r a d i a l  groups.  X-ray powder d i f f r a c t i o n data f o r t h i s compound i s g i v e n i n Table 6.  I t does not resemble any known m i n e r a l or  previously reported s i l i c a t e UBC  compound.  X2852  I  10 9 7 2  6 3 1 2 1  Table 6.  Pe/MnO d  I i  3.98 3.73 3.28 3.08  1 2  2.77  1  2.98  2.67 2.28 2.22  2.16  a T 5  k i 2  1  k  d 2.12  1.989 1.961* 1.870 1.803 1.706 1.61*0 1.595 1.1*95  X-ray Data f o r B a ^ P e ^ e ^ S i O ^ J l O  P l a t e I I I X-ray Powder Photograph o f the Compound 5Ba0.2PeO. P e 0 o . l 0 S i 0 p . UBC X 2 8 5 8 2  20  A l t e r a t i o n Products The  of K e e l e i t e :  a l t e r a t i o n products  of k e e l e i t e i n c l u d e  s e v e r a l minerals which are of hydrothermal which have been i d e n t i f i e d as carbonates cium.  The  hydrothermal  designated by  replacement  o r i g i n and s e v e r a l  of barium and  minerals  cal-  have been  letters.  The most abundant a l t e r a t i o n product i s M i n e r a l C, a f i n e l y f i b r o u s blue m i n e r a l which i s s t r i k i n g l y p l e o c h r o i c i n b r i l l i a n t blues and p a l e y e l l o w s .  This m i n e r a l a l s o  appears as an a l t e r a t i o n of g i l l e s p i t e and was  f i r s t re-  p o r t e d by S c h a l l e r ^ i n 1 9 2 9 i n a s s o c i a t i o n w i t h g i l l e s p i t e from Dry D e l t a , A l a s k a . from Mariposa  I t i s a l s o found I n the  County, C a l i f o r n i a .  c r i b e d by P a b s t  7  in  P l a t e IV  gillespite  T h i s occurrence was  19U3-  M i n e r a l C (blue) which has r e p l a c e d g i l l e s p i t e (pink) and k e e l e i t e (white). X7£.  des-  21 I t s o p t i c a l p r o p e r t i e s are as f o l l o w s . Color  Form  -  -  blue, strongly pleochroic with x - c o l o r l e s s to p a l e y e l l o w , y - pale blue, z - dark b l u e . F i b r o u s aggregates, i n t i m a t e l y mixed w i t h a s e r i c i t i c m i n e r a l .  Cleavage  - one cleavage p a r a l l e l to the l e n g t h of the c r y s t a l , and one p o o r l y developed cleavage or p a r t i n g p e r p e n d i c u l a r to the first.  I n d i c e s of R e f r a c t i o n  -  = 1.659 ± .005 ny = 1.70i* ± .005 n = 1.70i| ± .005 z  Birefringence  -  Extinction  parallel.  -  n  z  - n  x  =  .045»  O r i e n t a t i o n - the f a s t r a y i s p a r a l l e l Eo the l e n g t h of the c r y s t a l . Twinning  -  no twinning  Optic Angle and  Sign  -  observed. the f i g u r e i s  b i a x i a l negative w i t h 2 V ~ X  Dispersion  -  strong, with r <  A possible optical Is presented  i n F i g u r e 2.  45°*  v.  o r i e n t a t i o n f o r Mineral C  22  Figure  2.  Possible Optic O r i e n t a t i o n of M i n e r a l C.,.  S e v e r a l X - r a y powder photographs were taken on p i c k e d g r a i n s , and although and  the m i n e r a l  i s finely  i n t i m a t e l y mixed w i t h k e e l e i t e and g i l l e s p i t e ,  making i t d i f f i c u l t  on d i f f e r e n t m a t e r i a l .  i n Table 7. M i n e r a l C - UBC X261+6  3.62 .  3 10  3  I  1.689  3.35  3.0I|  2  1.605 1.51+0 1.508  3.21  k  Is  I  k k  i  2.1+7 2.26 2.11  2  1.1+17  1  1.377 1.318 1.291 1.258  2.04  u 5  1.888 1.821  k Table  7.  1.661+  2.81 2.59  2  thus  to o b t a i n pure m a t e r i a l , the same  X-ray p a t t e r n was obtained data i s presented  divided  2  i  2  1  1.1+82  X-ray Data f o r M i n e r a l C  X-ray  Plate V  X-ray Powder Photograph o f M i n e r a l C, Yukon T e r r i t o r y , UBC X26i|6 Cu/NiO.  A c l o s e d tube t e s t of M i n e r a l C y i e l d e d a small amount of water. disappeared  The blue c o l o r of the m i n e r a l  and a yellow-brown, g r a n u l a r r e s i d u e  i n the tube.  A spectrographic  remained  analysis of Mineral C  showed the presence of minor boron and l i t h i u m i n a d d i t i o n to those elements detected i n k e e l e i t e and g l l l e s p i t e . r e s u l t s are t a b u l a t e d i n Table  8.  Major  Minor  Trace  SI Pe Ba  B Li  Mn Mg Al Ca Cu Zn  Table 8.  Spectrographic M i n e r a l C.  A n a l y s i s of  The  M i n e r a l C, as s t a t e d p r e v i o u s l y , r e p l a c e s both k e e l e i t e and g i l l e s p i t e .  In g i l l e s p i t e , i t f o l l o w s the  prominent b a s a l cleavage, but i n k e e l e i t e , the replacement has no p r e f e r r e d d i r e c t i o n .  The a l t e r a t i o n product i s  commonly a heterogeneous product  c o n s i s t i n g of M i n e r a l C  and f i n e l y f i b r o u s aggregates of a s e r i c i t i c - l o o k i n g m a t e r i a l . Another a l t e r a t i o n product has been designated  of k e e l e i t e , which  M i n e r a l D, i s a b r i l l i a n t y e l l o w ,  t r o p i c m i n e r a l or m i n e r a l o i d which a l s o r e p l a c e s I t may be the m i n e r a l mentioned by Rogers  iso-  gillespite.  i n 1 9 3 2 as  o c c u r r i n g with sanbornite from Mariposa County, C a l i f o r n i a . This mineral sequently,  occurs  only i n very s m a l l amounts and con-  s u f f i c i e n t m a t e r i a l f o r X-ray or s p e c t r o g r a p h i c  analyses was u n a v a i l a b l e .  Another y e l l o w m i n e r a l , which  occurs as f i b r o u s aggregates c u t t i n g through k e e l e i t e , has a s l i g h t b i r e f r i n g e n c e and may be s t i l l t i n c t species.  T h i s mineral I s designated  another d i s M i n e r a l P and  i s shown i n P l a t e VI.  P l a t e VI  M i n e r a l P(yellow) c u t t i n g k e e l e i t e (white). The dark brown m i n e r a l i s s p h a l e r i t e . X75-  25 A f o u r t h n i n e r a l , which has been designated M i n e r a l E , i s r e l a t i v e l y common as s c a t t e r e d anhedral g r a i n s throughout the m i n e r a l ,  Plate VII  sanbornite.  M i n e r a l E (yellow) which has formed by a l t e r a t i o n of sanbornite (white). X75  I t a l s o occurs i n small amounts i n minute cracks t r a v e r s i n g k e e l e i t e and i t s a s s o c i a t e d m i n e r a l s . It i s strikingly pleochroic i n b r i l l i a n t  orange and y e l l o w .  A s p e c t r o g r a p h i c a n a l y s i s showed the presence o f major q u a n t i t i e s o f manganese and t i t a n i u m i n a d d i t i o n to those elements contained  i n keeleite, g l l l e s p i t e ,  and s a n b o r n i t e .  The r e s u l t s of the s p e c t r o g r a p h i c a n a l y s i s are presented i n Table  9. Major Ba Si Pe Mn Ti Table  Minor Ca  9.  Spectrographic Mineral E.  Trace Mg Sn Al  Analysis of  26  A c l o s e d tube t e s t of M i n e r a l E y i e l d e d d e t e c t able amounts o f water. the b l u e m i n e r a l .  No c o l o r change took p l a c e as i n  X-ray powder photographs o f the m i n e r a l  occurring with sanbornite  and o f t h a t o c c u r r i n g i n cracks  t r a v e r s i n g k e e l e i t e gave i d e n t i c a l p a t t e r s .  The r e s u l t s  are t a b u l a t e d i n Table 1 0 .  M i n e r a l E - UBC X25l*8 Cu/NiO I  10 2 k 2 8 2 2 3 1 1  Table 1 0 .  d  I  d  3.75  2 2 2I  2.16 2.09 2.0i* 1.965 1.910 1.821* 1.71*9 1.650 1.1*27  3.55  3.31 2.91 2.83 2.74 2.60 2.1*9 2.21  2 2 2 3 3  X-ray Data f o r M i n e r a l E .  27  • Plate VIII  X-ray Powder Photographs of M i n e r a l E. (Top) M i n e r a l E a s s o c i a t e d w i t h s a n b o r n i t e , Yukon T e r r i t o r y , UBC X2548 Cu/NiO (Bottom) M i n e r a l E a s s o c i a t e d w i t h k e e l e i t e , Yukon T e r r i t o r y , UBC  X2976  Cu/NiO  In a d d i t i o n to the replacement m i n e r a l s c r i b e d i n the f o r e g o i n g s e c t i o n , s e v e r a l unusual minerals are p r e s e n t to weathering.  The  dessupergene  on the specimens which were exposed first  of these commonly occurs as a  very f i n e - g r a i n e d ocherous powder i n t h i n c o a t i n g s keeleite.  Where k e e l e i t e i s mixed w i t h a p p r e c i a b l e quan-  t i t i e s o f g l l l e s p i t e , i t g i v e s an unusual mottled  on  appearance to the r o c k s .  r e d and  yellow  An X-ray powder photo-  graph o f t h i s m a t e r i a l showed only a few very weak l i n e s  28  indicating a poorly c r y s t a l l i n e  material.  The s u r f a c e s of many o f the specimens with layers  are  coated  of b o t r y o i d a l w h i t e m a t e r i a l , most of w h i c h  was d e t e r m i n e d as w i t h e r i t e and o p a l .  Some of i t  is  a p p a r e n t l y a more complex m i x t u r e of b a r i u m - c a l c i u m c a r bonates.  A comparison o f an X - r a y powder photograph of  t h i s m a t e r i a l w i t h those o f a l s t o n i t e ,  the  orthorhombic  b a r i u m - c a l c i u m c a r b o n a t e and o f b a r y t o c a l c i t e , c l i n i c dimorph, showed t h a t the supergene neither  of t h e s e m i n e r a l s .  i t s mono-  p r o d u c t was  However, a comparison w i t h 9  X - r a y d i f f r a c t i o n d a t a of s y n t h e t i c barytocalcite"^  alstonite  and  p r o v e d almost c e r t a i n l y t h a t the  supergene  p r o d u c t i s a m i x t u r e of b o t h these c a r b o n a t e s a l t s . comparison of X - r a y d i f f r a c t i o n d a t a f o r the w h i t e gene c o a t i n g , alstonite  synthetic barytocalcite,  and  i s given i n Table 11.  \  A super-  synthetic  29  White UBC  1  7 3 10  Coating X2973  1*.1*8 3.99 3.69 3.11+  S y n t h e t i c Barytoc a l c i t e . A.S.T.M, Index Car I - O 7 7 O  3.96  25  100  3.16  100 62 31 10  1*0  2.51*  6 6 6  2.15 1.991+ 1.933  30 30 25  2.11+ 2.00 1.91+  5 3  1.61+2 1.563  13 13 3 5  1.61* 1.57 1.51 1.1*7  3 k  1.39 1.31*  1 1  1.337 1.318  Table  1.32  1.29 1.28 11.  7  50  2.56  1.1*75  Synthetic Alstoni t e . A.S.T.M. Index Card 3 - 0 3 2 2  k  37 17 31 2 12 7  l*.5i 3.93 3.68 3.12 2.60 2.51* 2.27 2.13 2.00 1.92 1.81+ 1.61* 1.56  5  1.1*9 1.1*6  5 7  1.36 1.33 1.27 1.22  2  2  5  Comparison of X-ray d i f f r a c t i o n data o f White Coating, S y n t h e t i c B a r y t o c a l c i t e and S y n t h e t i c Alstonite.  30  A.  B,  D.  Plate A. B.  IX  X-ray Powder Photographs o f BariumCalcium Carbonates.  C.  W i t h e r i t e , Yukon T e r r i t o r y - UBC X 2 ^ 9 2 Cu/NiO. Mixed Carbonates, Yukon T e r r i t o r y - UBC X 2 9 7 3 Cu/NiO. B a r y t o c a l c i t e , Cumberland - UBC X 2 9 8 2 Cu/NiO.  D.  A l s t o n i t e , Cumberland  - UBC  X2988,  Cu/NiO.  A comparison of X-ray p a t t e r n s B, C, and D i n Plate  IX shows that the supergene mixed carbonates (B)  bear no s i m i l a r i t y t o e i t h e r b a r y t o c a l c i t e (D).  However, the X-ray d a t a f o r s y n t h e t i c  barytocalcite coatings.  (C) or a l s t o n i t e a l s t o n i t e and  are s t r i k i n g l y c l o s e t o that o f the supergene  31 This anomoly is explained later i n the section on paragenesis. Associated Minerals: The minerals which occur i n association with keeleite include the minerals which are found usually In contact limestones such as garnet, quartz, and hedenbergite.  The  latter mineral occurs commonly i n such mineral deposits with chalcopyrite.  It is present i n the keeleite assemb-  lage with pyrrhotite and marcasite.  Occasional very small  grains of magnetite were noted In some thin sections.  The  remaining minerals found i n the keeleite assemblage are very rare barium s i l i c a t e minerals, most of which are known only i n one or two l o c a l i t i e s , and many of which are probably new species.  Those minerals which occur as altera-  tion products have been described i n the section on that subject.  Three additional minerals which occur with keeleite  are taramellite ( B a ^ F e F ^ T i C S ^ ^ C O H ) ^ gillespite (BaPeSi^0 ), and sanbornite (BaSi20£). 10  Taramellite occurs as small equant grains or r e l i c t crystals disseminated throughout keeleite, quartz, g i l lespite, and Mineral C. A new formula which is proposed for the mineral taramellite and which i s based on a chemical analysis published by M a z z i i n 1957. 11  Plate X  R e l i c t c r y s t a l s of t a r a m e l l i t e i n quartz and k e e l e i t e X7£.  Taramellite (Pink)  (yellow) i n g l l l e s p i t e X75.  33  The  f o l l o w i n g o p t i c a l p r o p e r t i e s were d e t e r -  mined i n t h i n sections or on i n d i v i d u a l g r a i n s i n immersion oils: Color P l e o c h r o i c y e l l o w to deep brown, x - l i g h t yellow, y - l i g h t yellow, z - dark brown. Form and Cleavage s h o r t p r i s m a t i c g r a i n s w i t h square cross-sections"; one poor cleavage p a r a l l e l to the l e n g t h of the c r y s t a l . Indices of R e f r a c t i o n - n ~ Birefringence not determined, interfered.  I.76  strong pleochroism  Extinction - parallel. Twinning  - no twinning  observed.  O p t i c Angle and S i g n the f i g u r e i s b i a x i a l p o s i t i v e w i t h 2V =  35°.  Dispersion - strong, with  r>v.  These p r o p e r t i e s compare c l o s e l y w i t h those of t a r a m e l l i t e from the type l o c a l i t y , C a n d o g l i a ,  Italy.  A s p e c t r o g r a p h i c a n a l y s i s of t a r a m e l l i t e  from  the Yukon l o c a l i t y gave the r e s u l t s which are presented i n Table  12. Major Ba Fe Ti Si  Table 1 2 .  Minor Mg Ca B  Trace Mn Sn Cu Ag Pb Zn Ha Al  Spectrographic Analysis of T a r a m e l l i t e , (Ross R i v e r , Y.T.)  31*.  Taramellite  a l s o occurs i n sanbornite  specimens from Mariposa County, C a l i f o r n i a . Rogers^ mentioned an unknown brown p l e o c h r o l c which occurred i n 1929,  i n that assemblage.  described  (BaSi20^)  I n 1932, mineral  In addition, Schaller ,  a p l e o c h r o l c y e l l o w to deep brown m i n e r a l  occurring i n g i l l e s p i t e  specimens from Dry D e l t a ,  Alaska.  Specimens from the l o c a l i t y were examined by the author, and i t i s believed  that t h i s m i n e r a l i s a l s o t a r a m e l l i t e . The  X-ray d i f f r a c t i o n d a t a f o r m a t e r i a l from Mariposa and Yukon i s compared to t h a t f o r t a r a m e l l i t e from the type  locality  i n Table 1 3 . Candoglia, I t a l y UBC X25i|6 Pe/MnO  Ross R i v e r , Y.T. UBC X 2 i * 7 9 Pe/MnO  I  d  I  d  1 2 8 1  7.00 6.12 3.86 3.69 3.1*8 3.33 3.16 3.02 2.79 2.59 2.1^8 2.1*0 2.31 2.18 2.06 1.989 I.878  1 1 8 1  6.92 6.19 3.90 3.69  f  52 2 10 6 6 3 3 2 ii 2 2 1  -  3 3 1 2 2 1*  • - ..  1.798 1.71*1* 1.699 1.638 1.521*  plus  -  -  1* 1 10 3 5 1 1 1 1* 1 1 1  3.33 3.18 3.03 2.80 2.61 2.1*9 2.1*0 2.32 2.18 2.08 1.998 1.881  2 1  1.791* I.752  1 3  1.61*2 1.533  -  -  -  s e v e r a l more d i f f u s e  lines  Mariposa C t y , C a l i f . UBC X 2 6 8 9 Pe/MnO I  d  _ 1 2 7 2 1 6 1 10 5 6 3 3. 2  —  1* 2 1 1 3 3 2 1 22 1*  Table 1 3 . X-ray data f o r T a r a m e l l i t e .  6.09 3.88 3.71 3.50 3.31* 3.19 3.01* 2.81 2.60 2.50 2.1*1 2.33 2.18 2.08 1.998 1.886 1.815 1.798 1.753 1.708 1.658 1.538  ?  35  P l a t e XI  X-ray Powder Photographs of Taramellite. (Top) T a r a m e l l i t e , C a n d o g l i a , UBC X251+6 Fe/MnO. (Center) T a r a m e l l i t e , C a l i f o r n i a , UBC X2689 Fe/Mno. (Bottom) T a r a m e l l i t e , Y.T., UBC X 2 5 7 0 Fe/MnO. 11  In 1957,  F l o r e n z o Mazzi c a l c u l a t e d the formula,  (Ba,Ca, Ua) ( F e , M g ) F e T i ( S i ^ C ) (OH)^ f o r the m i n e r a l t a r a i|  2  L2  m e l l i t e from a chemical a n a l y s i s on m a t e r i a l d r i e d at 110°C.  A r e c a l c u l a t i o n by the author based on the same  a n a l y s i s gave the formula B a ^ F e F e T i ( S i 0 3 ) g . ( O H ) ^ . 2  This  formula f i t s the a n a l y s i s b e t t e r , and i s suggested as the c o r r e c t one. Table 11+.  The method of c a l c u l a t i o n i s presented I n  36 Oxide Si0  2  Tio|  Pe20o PeO MgO BaO CaO Ng20 K0 H0 2  2  %  Mol.Wt.  Mol. R a t i o  .565 .096 .076 .052 .020 .245 .020 .013 .001 .117  7.91 1.34 1.06 1.01  60.06 79.9 159.7 71.58 i+0.32 153.36 56.08 62.0 9i|.2 18.0  33.9 7-7 12.2 3.7 0.8 37.5 1.1 0.8 0.1 2.1  Table 14«  | >  3.90 1.65  Chemical A n a l y s i s of T a r a m e l l i t e and C a l c u l a t i o n of i t s Formula.  A f a c t o r of 14 was ratios.  Mol.P.  used t o o b t a i n the m o l e c u l a r  The formula which r e s u l t e d from the above c a l -  c u l a t i o n s i s 4BaO.FeO.Fe2O3.TiO2.8SiO2.2H2O or i n the more c o n v e n t i o n a l manner, B a ^ F e F e ^ T I f S I O ^ ^ O H ^ . t a r a m e l l i t e i s t h e r e f o r e c l a s s e d as an Glllespite  The  mineral  inosilicate.  (BaFeSih.O^Q) occurs as  crystalline  masses i n a skarn c o n s i s t i n g of hedenbergite,  andradite,  q u a r t z , k e e l e i t e , and l e s s e r amounts of the other m i n e r a l s d e s c r i b e d under other s e c t i o n s .  G l l l e s p i t e i s a deep r o s e  r e d c o l o r , has a prominent micaceous cleavage, a p e a r l y l u s t r e , a hardness  of 3,  I t s a l t e r a t i o n products with k e e l e i t e .  and a s p e c i f i c g r a v i t y of 3«33» are the same m i n e r a l s which occur  37  Plate XII  The  G l l l e s p i t e (pink), keeleite (white), and t a r a m e l l i t e (brown). X75  o p t i c a l p r o p e r t i e s of g l l l e s p i t e are as f o l l o w s : Color  - strongly pleochroic 0 = p a l e p i n k to c o l o r l e s s E = deep rose r e d .  Form and Cleavage - anhedral g r a i n s w i t h a p e r f e c t b a s a l cleavage. I n d i c e s of R e f r a c t i o n  - n~1.62.  Birefringence  -  Extinction  parallel.  Twinning  -  very weak.  no twinning  observed.  O p t i c Angle and S i g n - the f i g u r e i s u n i a x i a l negative. These p r o p e r t i e s compare c l o s e l y w i t h obtained f o r g l l l e s p i t e from the two D e l t a , A l a s k a and Mariposa m i n e r a l was  localities,  County, C a l i f o r n i a .  f i r s t d i s c o v e r e d by W.T.  Schaller  those Dry The  (1929)^  i n a s i n g l e specimen from a g l a c i a l moraine at the head of Dry D e l t a , A l a s k a Range, A l a s k a .  The m i n e r a l assemblage  i n the A l a s k a specimen i s very s i m i l a r to t h a t i n the  38  Ross R i v e r specimens except t h a t k e e l e i t e i s absent i n the  former.  The only other p r e v i o u s l y r e p o r t e d  for  glllespite  i s near I n c l i n e , Mariposa County,  locality Calif.  No k e e l e i t e has been r e p o r t e d from that l o c a l i t y , b u t the  remainder of the assemblage  that of the Ross R i v e r  i s almost i d e n t i c a l t o  specimens.  Table 15, which f o l l o w s , p r e s e n t s a comparison of X-ray d a t a o f specimens from C a l i f o r n i a  and Yukon  Territory. Ross R i v e r , Y.T. UBC X2188 Pe/MnO  10  7-89  4.42  8  k  3.9-9  2  3.55 3.40 3.19  8 8  -  2  2.71*  3  2.66  ?  2.1*0  1  ¥ s 1  £ 2  1  2.52 2.29  2.22 2.05 1.998 1.91*0 1.875 1.771 1.531* 1.1*78  2 3  Table 15.  Mariposa Cty., C a l i f , UBC X2187 Pe/MnO  10  8 3  2  8 7 1  2  3 1 2 5 2  -  1 1  2  I  S 2 3  X-ray Data f o r G l l l e s p i t e .  7.95  1*.03 3.55 3.1*0 3.20 3.10 2.75 2.67 2.52 2.39 2.29  2.00  1.937 1*881 1.771* 1.656 1.51*3 1.1*79  39 A s p e c t r o g r a p h i c a n a l y s i s of g i l l e s p i t e  from  the Yukon occurrence i s presented i n Table 16.  Major  Minor  Ba Pe Si  crystals  Trace  Al  Mg B Ca Mn Cu Zn Ti Na  T a b l e 16.  Spectrographic A n a l y s i s of G i l l e s p i t e .  Sanbornite  (BaSi 0^)  occurs as f i n e - g r a i n e d  2  ( 0 . 5 t o 2.0 mm.)  a s s o c i a t e d w i t h M i n e r a l E,  q u a r t z , hedenbergite, and w i t h e r i t e .  I t was not found  w i t h k e e l e i t e , but o c c u r r e d i n an outcropping lense' about 100 f e e t away from the igneous  contact.  Sanbornite  r e c o g n i z e d i n t h i n s e c t i o n by I t s c h a r a c t e r i s t i c p r o p e r t i e s which are as f o l l o w s : Color  -  colorless i n thin section.  Form and Cleavage - anhedral g r a i n s w i t h a p e r f e c t b a s a l cleavage. I n d i c e s of R e f r a c t i o n n = 1.60 Z .005 n = 1.62 ± ,005 n = 1.62 + .005 x  y  z  Birefringence Extinction  -  n  2  - n  x  =  .020.  - i n c l i n e d e x t i n c t i o n , small angle.  O r i e n t a t i o n - the f a s t r a y i s p a r a l l e l to the cleavage. Twinning  -  no twinning  observed.  was  optical  1*0 Optic Angle and S i g n  -  the f i g u r e i s  b i a x i a l negative w i t h 2V = 6£ . Dispersion  -  not  observed.  A s p e c t r o g r a p h i c a n a l y s i s of s a n b o r n i t e from the Yukon T e r r i t o r y i s presented i n Table Minor  Major  Table 17»  Trace  Na Al  Ba Si  17.  Fe Cu Ca Mn Mg  S p e c t r o g r a p h i c A n a l y s i s of Sanbornite.  Sanbornite was  f i r s t d e s c r i b e d by Rogers (1932)  from specimens found i n Mariposa County, C a l i f o r n i a , the c r y s t a l s t r u c t u r e was  determined by Douglass  u s i n g specimens from the same l o c a l i t y .  and  (195>8)  12  X-ray powder  data on specimens from Yukon T e r r i t o r y i s compared w i t h that obtained by Douglass Table  18.  on Mariposa  sanbornite i n  8  Table 18.  X-ray Data f o r S a n b o r n i t e .  Ross R i v e r , Y.T. UBC X2£57 Cu/NiO I  d  Mariposa C t y . , C a l i f . R.M. Douglass 1  d  1* 3  6.81 5.01|  30 30  8  3.97  8 1 10  3.38 3.21 3.09  100 10 50 70 20 75 5 5 55 15 5  3.97 3.82 3.1*22 3.31*2 3.226 3.095 2.980 2.888 2.720 2.571* 2.5141  .5 .5 15 5  2.391* 2.327 2.317 2.281  10 30  2.236 2.226  15 25 l*o 10  2.193 2.162 2.130 2.109  5 15  2.038 2.025  -  10  1.990  2  1.911+  10  1.921  -  -  10'  1.903  -  --  7 2 —  -  -  2.72 2.57 —  -  -  —  —  2  2.30  —  —  -  -  3 —  5  -  —  1*  -  2  -  3 —  -  1*  2.23 —  2.15 —  2.02  20 5 20 1.791* 5 5 1.689 15 Plus s e v e r a l more l i n e s . 1.81*8  —  6.79 5.08  1.850 1.815 1.793 1.736 1.709 1.690  42  Plate XIII (Top) (Bottom)  X-ray Powder Photographs of S a n b o r n i t e . Sanbornite, C a l i f o r n i a , UBC X 2 5 5 6 Cu/NiO. Sanbornite, Y.T., UBC X 2 5 5 7 Cu/NIO.  Paragenesis: The m i n e r a l d e p o s i t i s o f the c o n t a c t metasoraatic c l a s s and has r e s u l t e d from the i n t r u s i o n of a quartz monzonite stock i n t o country rock c o n s i s t i n g o f s l a t e s , p h y l l i t e s , l i m e s t o n e s , and other low grade r e g i o n a l l y metamorphosed types. was  The metasomatic  replacement  favoured i n l i m e - r i c h l e n s e s present i n the o r i g i n a l  metasediments.  High temperatures  textural relationships  are i n d i c a t e d by  i n the s u l f i d e s , and r a p i d  i s suggested by the presence  cooling  of r e l i c t m i n e r a l c r y s t a l s  and pseudomorphs i n the skarn assemblage.  Rapid changes  43  i n temperature  and/or p r e s s u r e are a l s o suggested by  the extreme zoning i n p l a g i o c l a s e f e l d s p a r s  ( A n ^ to An o) 2  w i t h i n the i n t r u s i v e body. R e l a t i o n s h i p s between a l l the m i n e r a l s i n the assemblage were not observed i n t h i n s e c t i o n , but s u f f i c i e n t evidence was p r e s e n t to allow some c o n c l u s i o n s to be drawn r e g a r d i n g the paragenesis of the d e p o s i t . For convenience,  the p a r a g e n e t i c sequence i s d i v i d e d  i n t o three p a r t s or phases.  T h i s d i v i s i o n does not  n e c e s s a r i l y imply that there were three separate p e r i o d s of m i n e r a l i z a t i o n . was  I t i s q u i t e probable t h a t d e p o s i t i o n  continuous, and that the v a r i o u s m i n e r a l s were de-  p o s i t e d i n a d e f i n i t e sequence c o n t r o l l e d by r a p i d changes i n p r e s s u r e , temperature somatic  and the composition o f the meta-  fluids. The f i r s t phase was one o f temperature  increase  which r e s u l t e d i n the f o r m a t i o n of garnet and pyroxene. Some specimens c o n s i s t e s s e n t i a l l y o f euhedral c r y s t a l s of pyroxene and anhedral garnet i n k e e l e i t e and i t s a l t e r a t i o n products.  The garnet has p a r t i a l l y r e p l a c e d  hedenbergite, but the r e l a t i o n s h i p o f these m i n e r a l s t o k e e l e i t e i s obscured by the a l t e r a t i o n of k e e l e i t e and the l a t e r a d d i t i o n o f s u l f i d e m i n e r a l s which r e p l a c e a l l silicates. The second phase c o n s i s t e d of the metasomatic a d d i t i o n of barium,  titanium, s i l i c a ,  boron, l i t h i u m , a i d manganese.  i r o n , and minor  T h i s metasomatism r e s u l t e d  kk i n the f o r m a t i o n of g l l l e s p i t e , k e e l e i t e , and t a r a m e l l i t e .  sanbornite,  T a r a m e l l i t e i s b e l i e v e d to be e a r l y  because i t commonly occurs as r e l i c t c r y s t a l s which have been p a r t l y r e p l a c e d by other m i n e r a l s .  I n one  specimen,  where t a r a m e l l i t e occurs w i t h k e e l e i t e and q u a r t z , almost every g r a i n of the t a r a m e l l i t e i s so badly corroded  as  to leave only a bare network of the o r i g i n a l m i n e r a l . K e e l e i t e and g i l l e s p i t e may  have been contemporaneous,  but i n one s e c t i o n , the former m i n e r a l was  seen to cut  across a c r y s t a l of g i l l e s p i t e , and f u r t h e r , g i l l e s p i t e c r y s t a l s are sometimes seen to b u t t up a g a i n s t the more euhedral k e e l e i t e g r a i n s . paragenesis  The r e l a t i v e p o s i t i o n i n the  of s a n b o r n i t e i s not known because i t occurs  s e p a r a t e l y i n a lense-shaped main d e p o s i t .  The  bed about 100  a l t e r a t i o n products  f e e t from the  are a l s o i n c l u d e d  i n t h i s phase although they are a l l o b v i o u s l y l a t e r . The presence of water and such elements as boron and l i t h i u m , which were d e t e c t e d i n M i n e r a l C, suggests  a  r a t h e r l a t e stage i n the process, q u i t e probably f o l l o w i n g even the d e p o s i t i o n o f s u l f i d e s .  M i n e r a l C,  the  blue f i b r o u s m i n e r a l , has r e p l a c e d g i l l e s p i t e along i t s prominent b a s a l cleavage  and i t s g r a i n boundaries.  In  some i n s t a n c e s , i t has completely r e p l a c e d t h a t m i n e r a l . K e e l e i t e i s a p p a r e n t l y l e s s s u s c e p t i b l e to replacement by M i n e r a l C, but has moderate extent.  a l s o been r e p l a c e d to a r e l a t i v e l y  M i n e r a l 3D has r e p l a c e d k e e l e i t e i n many  s e c t i o n s , p a r t i c u l a r l y I n those s e c t i o n s c o n t a i n i n g  45 s u l f i d e minerals. replacement  T h i s r e l a t i o n s h i p suggests  t h a t the  of g i l l e s p i t e and k e e l e i t e by M i n e r a l D  contemporaneous w i t h s u l f i d e emplacement. m i n e r a l seen to r e p l a c e sanbornite was  The  was  only  M i n e r a l E.  The  l a t t e r occurs as anhedral g r a i n s along the g r a i n bound a r i e s of s a n b o r n i t e .  I t a l s o occurs i n s m a l l q u a n t i t y  i n minute f r a c t u r e s i n the k e e l e i t e - g i l l e s p i t e r o c k s . The  t h i r d phase i s c o n s i d e r e d to embrace the  emplacement of the s u l f i d e m i n e r a l s .  Chalcopyrite  s p h a l e r i t e , p y r r h o t i t e , and m a r c a s i t e  have r e p l a c e d a l l  silicates.  C h a l c o p y r i t e occurs as exsolved rims  b l e b s w i t h i n and around s p h a l e r i t e g r a i n s g i v i n g "emulsion"  or "mottled" t e x t u r e .  p y r i t e are o r i e n t e d i n the (111) sphalerite.  and an  Some l a t h s of c h a l c o or ( 1 0 0 )  planes  of  A c c o r d i n g to E d w a r d s ^ ^ these t e x t u r e s r e -  present a l l stages i n the a r r e s t e d d i f f u s i o n of exs o l u t i o n c h a l c o p y r i t e to the g r a i n boundaries s p h a l e r i t e host.  He  of i t s  states also that t h i s texture i s  the r e s u l t of h i g h temperature d e p o s i t i o n and r a p i d  cool-  i n g , and t h a t the temperature of unmixing i s 350  450  degrees C.  P y r r h o t i t e e x h i b i t s mutual boundaries  -  with  the other s u l f i d e s and i s probably contemporaneous w i t h them, p o s s i b l y d e p o s i t e d from a complex s o l i d  solution  w i t h complete s e g r e g a t i o n of p y r r h o t i t e from the other sulfides.  M a r c a s i t e has r e p l a c e d p y r r h o t i t e to a con-  s i d e r a b l e extent along f r a c t u r e s . replacement  Edwards s t a t e s t h a t  of p y r r h o t i t e by m a r c a s i t e may  be caused  by  1*6  a change i n the pH and temperature mineralizing  of the r e s i d u a l  solutions.  A number of b a r i t e v e i n s occur i n the immediate v i c i n i t y of the m i n e r a l d e p o s i t . from two  or t h r e e Inches  t o one f o o t and may  s e v e r a l hundred f e e t l o n g . well-formed  They range i n width be up t o  The b a r i t e occurs i n v e r y  c r y s t a l s up t o three inches i n l e n g t h or i n  p l a t e s forming a boxwork.  These v e i n s cut across the  country rock and the m i n e r a l i z e d zones,  and are probably  the r e s u l t of a very l a t e stage i n the p a r a g e n e s i s . The f o r m a t i o n of white, supergene bariumc a l c i u m carbonates  as c o a t i n g s on the s u r f a c e r o c k s i s  a t t r i b u t e d to p r e c i p i t a t i o n from s o l u t i o n s at or very near the s u r f a c e .  The reason f o r t h i s b e l i e f i s found  i n the very c l o s e resemblance of the supergene to s y n t h e t i c barium-calcium  carbonates.  carbonates  The s y n t h e t i c  s a l t s were p r e c i p i t a t e d from s o l u t i o n s of CaCl2, BaCl2» and  and c a l l e d s y n t h e t i c b a r y t o c a l c l t e and  alston-  i t e even though t h e i r X-ray p a t t e r n s do not resemble of the n a t u r a l m i n e r a l s .  those  I t i s t h e r e f o r e suggested t h a t  the s y n t h e t i c m a t e r i a l s and those n a t u r a l m i n e r a l s  occur-  r i n g as supergene c o a t i n g s on k e e l e i t e are polymorphs of a l s t o n i t e and b a r y t o c a l c i t e w i t h the composition BaCa(C0.2)2. I t i s f u r t h e r suggested c a l c i t e may  t h a t n a t u r a l a l s t o n i t e and b a r y t o -  form o n l y under c o n s i d e r a b l e p r e s s u r e s of  COo.  hi CONCLUSIONS A new mineral, keeleite, is described.  The  chemical formula, based on chemical analysis and synthesis, is Ba^Ca Fe^(Al,Fe) (SiQ2)l2. 2  The mineral is  2  tentatively classed as an inosilicate.  Optical pro-  perties suggest that the mineral is orthorhombic. The minerals designated by the letters C, D, and E are probably new species. Three new localities for taramellite have been proven by X-ray and optical determinations.  In addition  to the type l o c a l i t y , Candoglia, Italy, taramellite occurs in the Yukon Territory, i n Mariposa County, California, and in the material from Dry Delta, Alaska.  Sanbornite,  previously a one-locality mineral, has also been shown to occur i n the Yukon Territory. The presence of supergene barium-calcium carbonates i n the deposit, which are similar to salts obtained synthetically, suggests a natural occurrence of minerals of composition BaCafCO^^*  If this assumption  is true, the minerals are probably polymorphs of alstonite and barytocalcite. A new formula, Ba, FeFe' Ti(SiO.) (0H)• , is sugn  gested for the mineral taramellite. A paragenetic sequence based on present evidence has been presented.  It is quite possible that this para-  genesis w i l l be revised with a more exhaustive examination  48  of the f i e l d relationships.  The author had the oppor-  tunity to spend only one day on the property, and i t is probable that careful investigation would reveal better crystallized material, additional mineral species, and more evidence for a paragenetic sequence.  1+9  BIBLIOGRAPHY 1.  Kindle, E . D . (191*5), "Geological Reconnaissance along the C'anolRoad from Teslin River to MacMillan Pass Yukon", Geological Survey of Canada, Paper 1*5 * 21.  2.  Wheeler, J.O. and Roddick, J.A. (1958) - the geological report of Operation Pelly is in preparation.  3.  Bowen, N.L. and Schairer, J.P. (1932), "The System FeO-Si02", Am. Jour, of Science, vols. 23-21*, 1932.  1*.  Schairer, J.P. and Yagi, Kenzo (1952), "The System P e 0 - A l 2 0 3 - S i 0 2 " , Am. Jour.-of Science, Bowen volume, 1952.  5.  Levin,  6.  Schaller, W.T. (1929), "The Properties and Associated Minerals of G i l l e s p i t e , " American Mineralogist, vol.ll*, pp.319-322.  7.  Pabst, A. (191*3), "Crystal Structure of Glllespite, BaFeSl),Q>i , " -American Mineralogist, v o l . 2 8 ,  and Ugrinic, (1951), "Journal of Research of the National Bureau of Standards," v o l . 5 1 , pp. 3 7 - 5 6 .  A  PP. 372-390.  8.  Rogers, A.P. (1932), "Sanbornite, a new barium silicate mineral from Mariposa County, C a l i f . , " American Mineralogist, v o l . 17, PP. i6i-i72~:  9. 10. 11.  —  A.S.T.M. X-ray Index Card 3-0322. A.S.T..M. X-ray Index Card I-O77O. Mazzi, Plorenzo (1957), "RIesame della taramellite," A t t i Soc.tosc.sci. ~nat., ser.A, v o l . 61*, 1957, PP. 237-245.  ;  12.  Douglass, R.M. (1958) "The Crystal Structure of Sanbornite, BaSi205," American Mineralogist, vol. 1*3, 1958.  13.  Edwards, A . B . , Textures of the Ore Minerals and Their Significance, Revised 195U. Aus. Inst. M.M., p. 100.  

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