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The Rainy Day mineral prospect Emmons, Richard Conrad 1920

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THE  RAINY  DAY  feilKERAl  by E . G. Emmons.  INTRODUCTION AND LOC^IIOII. TOPOGRAPHY. gggBRAL GDOLOGY. B3CI0EA1. •U00u.lt.  Vancouver Srou.%. Volcanies. Sutton Formation. Plutonics. Structure„ Anticlinal Fold. Lithology of :jatioline. Origin. E00E0LIC GEOLOGY. WORKINGS. MINERALOGY. PARuGHIIESIS. CLASSIFICATION AITD OONCLUSiDOITS,  PROSPiCiJ  "1". INTRODUCTION. The i'/est Coast of Vancouver Island is thickly wooded and rather mountainous,though to a much less degree than its interior. Numerous prospects have boon located on Barkley Bound  and of these  the Rainy Day has been chosen as representative of the contact metamorphic type,both with respect to geologic relations and estimated dimensions of the ore body. LOCATION. The property is situated 01S the cast shore of Henderson Lake about one and a half miles above the outlet ( Fig: 1.). prospect adits are less on a steep hillside.  The  than fifty feet above the level of the lake The outlet of the lake is a broad stream  emptying into Uchucklesit Harbour an arm of Barkley Sound and falls only a few feet in a distance of half a mile.  Dredging operations  have been carried on by the government making possible the commercial transportation of ore. TufuC^.IHY. The general trend of the mountain ranges of Vancouver Island is N 65  v/, this direction conforming roughly with the axes of folding  and planes of faulting of the district.  Glaciation has gouged out  the valleys giving them the typical U- shape and removing a great quantity of material.  Several large valleys have developed trans-  versely to the trend of the rocks, namely  N.E. and S,W..  Examples  are Alberni Canal, Henderson Lake, Pipestem and Effingham Inlets. It is probable that their relative  size is dus to  would be from the centre of the Island outward.  glaciation  which  These have been  "2". converted into Fiords with the exception of Henderson Lake which is a few feet  above high water level.  Other valleys equally impor-  tant have formed subsequent to the trend of the rocks and folding; as examples of these may be cited Sproat Lake, Mahmint Luke and the northern portion of Henderson Lake.  An area of lowlands borders I  the west c o a s t of t h e I s l a n d ; in the v i c i n i t y of Barlflfcey Sound i t  Ctf consists of folded sedimentary and plutonic rocks. Glapp (1). C. H. Glapp: Hem: 15. page 23. Geo: Surv: Can: that the Tertiary sediments  states  were deposited in small embayments off  a mountainous coast with bold promontaries  .  This proEess can be  seen still going on in Effingham Inlet where recent Ufjlift has brought several marine deposits above yea level and they are now suffering erosion by young streams.  G-jaa^L GEOLOGY. HSGIGIkJi. Island  The major portion of the rocks exposed on Vancouver  consists of sediments,and volcanic roeks - the Vancouver  Group of Dawson- which'are lower Uesosoio in age.  They are  con-  siderably folded and are intruded by both acidic and basic granitic roaks.  Other rock  types are found on the Island that do not  enter into the geology of the Rainy Day prospect.  During Pleisto-  cene times Vancouver Island was covered with ice which eroded deeply sending out valley glaciers to the lower levels and modifying the topography as already mentioned. LflCAL.  Altered -^ndesite predominates in the crystalline rocks of  the district.t  The volcanics are thought to have accumulated under  the sea, on the evidence that structure  thought to be pillow structur  "3". was observed ,and that beds of Limestone in which Clapp found marine fossils are intercalated in the volcanics.  The Limestone  is generally in thin lenses though occasional beds of considerable thickness were found.  .here intruded by rranitio rocks it is  metamorphosed into such minerals as garnet, epidote, amphihole and pyroxene. All the Vancouver ^rpup have been greatly folded and f.ulted causing the limestone beds to have various dips.  The strike cono forms roughly tb that of the axes of folding, namely, 11.65 d.  Following the deformation and probably during it there were intrusions of granitic rocks which,in general, followel a north-west,south-east trend,evidently the lines of weakness caused in the overlying beds by the regional folding.  These intrusives have been classified as  late Jurassic • ; (2). C.H.Glapp: Mem: 13: page 112.  Geo: Surv: Can:  Deposits of glacial drift caver areas in the district but do not enter into the geology of the Rainy Day prospodt. Vancouver Group.  These rocks have been subdivided by Clapp in  Southern Vancouver Island, chiefly on the basis of lithological differences.  The nomenclature employed by him will be applied to the rocks  encountered,where correlation is possible. Volcanics.  The preponderant rocks exposed in the district are  the Vancouver volcanics, which apparently form a belt parallel to that of the Island. belt.  with a trend  Henderson lake is situated in this  The volcanics are principally flow type and are represented  "4". "by amygdaloids .porphyries and tuffs.  No fragmental types were  found,however, in the iiranediate vicinity of the Rainy Day prospect. Alteration has taken place in all the rocks, being more pronounced near the intrusions. I.eta-andesite  is the most commonA  Uagascopically it  appears cs a dark green rock,usually porphyritic, the phenocrysts being felspar and hornblende.  Veinlets of epidote cut the andesite.  and occasionally fill the vesicles.  Small cubes  of pyrite could  often be detected in the hand specimen. Llicroscopioally the ixndesites were seen to be much altered in all the slides examined.  In places the original character  of  the ground mass was completely obliterated,the phenocrysts ssrbing to indicate the relative basicity of the unaltered material.  The  ground mass consists of felspar laths intergrown and being replaced S  c  by $eri$ite,chlorite and calcite.  The phenocrysts consist of  fel-  spar altering tc a^risite and hornblende considerably replaced by calcite and chlorite; the felspar phenocrysts are of the andesine variety.  The Iron leached from the ferrQ-magnesian minerals is  concentrated in patches about the slide. Some Of the raeta-andesite showed under the microscope a greater degree of petamorphism .  The hornblende phenoerysts  were  almost completely altered to chlorite,the original crystal boundarias usually being retained and also some of the structure; chlorite was abundantly present in all the field. Near solution channels the volcanics  are silicified making  the ground mass a fine aggregate of cjuartz grains usually associated with pyrite.  There were small areas of granular epidote and veinlets  "5".  of oalcite and epidote cut the rock. Dacite  occurred as a light green or almost white fine  grained rock,in which no quartz is visible to the unaided eye; it is found with the andesite but is quite easily distinguished by its colour. I.Iicroscopically the normal Sacite is seen to have porphyriti texture, the phanoerysts being hornblende, felspar and -quartz. The felspar is of the oligoclase-andesine variety, the hornblende the is altering to chlorite and epidote while anhedral phenocrysts of tz  crystals  enclose small felspar microlites.  The ground mass  is felted consisting of felspar laths simple or once twinned.  The  altered Dacite differs by having chlorite replacing the hornblende and kaolin a-' .1 ^erifite replacing the felspar. ..patite was found as a minor accessory in all the volcanics, and magnetite in the andesite. A thin section r&s uade of a rock impregnated with pyrite, selected from the face of a tunnel in which the o:;e lead had failed. The hand specimen was dark green in a>pearance with a flinty lustre, pyrite cubes being quite abundant.  Under the microscope the gangue  was se">n to consist wholly of quart* in small grains. The type of alteration undergone ijy the volcanics is known as to propylitic alteration and is thought to be due ascending hydrothermal solutions. ' (3). V, H. Emmons. Prin: Economic Geology: pccge 249. »7. Lindgi&an. Ore Deposits: page 478.  Sutton Formation.  Limestone lenses which occur interSedded in  the Vancouver volcanics have been determined by Qlapp as Lower Jurassic  "6".  they also occur thinly Interbeclded with tuff, in which case the limestone appears to be more impure.  Thin sections were not  made of the limestone,hut it is apparently finely crystalline with coarser veinlets of calcite running through it.  It is highly  probable that the limestone and volcanics are contemporaneous in age since they are folded and faulted together, both formed under the sea and generally closely associated.  The presence of frag-  mental types in other imrts of the district similarly associated with the limestone, also supports this view. Plutonies;  There are several intrusions of dyke and batholithic  rocks in Barkley, Sound and it is with one of these in particular that the Rainy Day prospect is concerned.  They have metamorphosed  and in places mineralized the overlying volcanics and limestone giving rise to several ore deposits. - quartz-diorite dyke occurs just north of the Rainy Day prospect adits; it is about two hundred yards in wiftth and has a general o strike of S 65 3. The superior resistance to erosion of the diori has resulted in the formation of a mountain on both sides of the lake,marking its location.  It is a medium coloured, coarse  grained rock quite rich in hornblende; in the hand speoimen it appeared guite fresh• Microscopically the normal diorite is holocrystalline, consisting essentially of BUDhedral crystals of hornblende altering to chlorite,and andesine felspar slightly altered to sericitev .yiiartz is present interstitially in small quantities; Apatite, Magnetite, and Titanite appear as accessary minerals-, The rock  tt 17 tl  therefore, is classified as a  ^^rtL-c' iorite.  The „ltared liorite is chloritised to a much  greater  extent and tho felspars are thickly clouded T"ith setieite.  The  The Iron_le^ched fron the ferro-roagnesian^.is segregated in patches in the slide.  Quartz,apparently  secondary, is present in  the altered rock; this alteration is produced ne^r the borders of the dyke and is evidently due to the solutions fro  bl e still warm  interior. Structure;  Aside from the major structures referred to and sr  topography, the structure In the vicinity of the prospect is connected with -fefrw igneous activity.  The intrusion of the diorite  dyke resulted in folding, faulting, and fracturing.  The fold-  ing and faulting followed almost the strike of the dyke, while the fracturing served to ohliterate nost of the traces of original structure. Strikes and dips of lines tone lenses measured on the shore,, where a continuous exposure could he found, were yuito irregular. (Sketches nade of this in tho field are shown in Fig 2.) evidence of deformation  SEEK  There was no  ?Ff££^&& in the dyke rock.  The n^rlhern adit has he en driven into an anticlinal fold that presents some very interesting geological feature-. ( Fig.3.) On the south side a fault cuts off the anticline and is thought to be genetically related to it:  the  a hundred feat by the tunnel*  fault m i l has been followed for A layer of gouge  lies between the  fold and the silicified andesite on tho south side of the f*.*ult plana The innermost of the concentric layers forruing tha fold consists of  "8". a pyroxene, separated from the next layer of the same mineral by c-arnet.  a  hand of  There is distinct parting in the garnet at angles of  about 90,, probably dodecahedral - these parting lines hoar a fixed relation to the plane of the garnet band.  Incipient crystallization  has developed in the garnet, the dodecahedron and trapezohedron having been recognized (iPig; 4 0 ) ,  Between the second and third  layers of pyroxene were some large fragments of limestone vith open spaces between them£  the  surfaces ox the fragments were weathered  and gave no information concerning their position.  It Is important  to note that the fragments were not wholly recrystu-llized.  All  three bands of pyroxene showed a tendency towards comb structure, the crystals standing out in better relief near their bases than toward the center.  Another band consisting of a fine grained  aggregate of vesicular epidote lay outside of the pyroxene.  leither  the epidote nor the pyroxene was fractured. The typical mixture of country rock,namely, limestone and andesite if8JS found bounding this formation where exposed.  In th  extreme center of the fold was some leached material,q,uite norous and black.  The contact of the garnet and pyroxene wus frozen but  well defined,that of the layers of pyroxene was not so solid, nor was that dividing the epidote and pyroxene; these latter were narked •u _,-, . surface^, . _ by a very thin S K S of material presumably gouge. Very slight metallization has taken place In the pyroxene, there being merely a few traces of the persistent mineral pyrite in thin sheets parallel to the longitudinal axes of the crystals. T;Ms association of sulphide and pyroxene was noticed elsewhere.  '9".  tlithology of the Anticline:  The garnet is "brown in colour  and very brittle, separating easily along the two sets of parting jdmmtf  these  ~^t<+rrw were noticed to cross and run parallel to  the plane of the hand.  Under the microscope one set of parting  linos was m^re numerous than the other, suggesting slight stress; a few crystal borders were noticed.  Veinlets of ^uartz gMtiojfc  cut the garnet.usually parallel to the^ parting . tests were run for  Qualitative  Aluminium, Iron, and Calcium, proving the  absence of Aluminium and the presence of Iron and §alcium.  It  is concluded that the garnet is of the andradite variety. The epidotlzed rock is rather lighi grea^finely granular and with many vesicles of snail slaw; there were no fractures evident.  Microscopically the rock consists almost wholly of epidote  in small euhedral crystals and grains.  Considerable leucoxene is  present lining the vesicles and scattered over the slide.  Chlorite  and quartz are found between the Bx^idote crystals many of which show wavy extinction. The Pyroxene is a dark green mineral consisting of elongated crystals in a sub-parallel arrangement.  Small veinlets of  Calcite run parallel to the other crystals and a little Pyrite is scattered through the rock.  Microscopically the Pyroxene h^s a o 0 high maximum extinction angle 42 - 43* The index of refraction v/astteternined,byimmersion, to be over 1.70, which limits the miner; to Augite or Hedenbergite.  A qualitative test for Aluminium  gave  a negative result; it is concluded, therefore, that the mineral is Hedenbergite.  The calcite contains numerous grains of Pyroxene  many of which show typically the square cross section with truncated corners  "10" The Garnet-Pyroxene contact shows crystals of Garnet intergrown with Pyroxene* which, is in short crystals, extinction angle 40- 44°,in sections showing one set of parallel cleavage lines|. Quartz grains are also present. Origin:  The study of the origin of the anticline has proved  interesting as throwing light on the order of events in contact metamorphism.  The intrusion was preceeded by a period of folding  and faulting which affected the covntry rock for some distance  SEXX  around; it will be remembered that the intrusion was undeformad. The result was the obliteration locally of all traces of original structure and the formation of channels which would facilitate the free movement of solutions.  In one small area may be represented,  in various sized fragments, limestone beds which were laid dovm undei widely different conditions.  There are fragments,therefore, in  juxtaposition some) of which may have been,under certain conditions, easily penetrable by solutions and others comparatively unaffected. Selective assimilation of materials from the solutions may give rise to similar results in different parts of the same bed and the propt* l ( 4) ducts may even be divided by a sharp M » e * The relatively (4)  U. H. Scimons: Principles of IDconomic Geology: page 226:  small  quantity of Iron in the epidote rock, estimated from its  mineral composition, would seem to preclude the possibility of its having formed from the andesite  'hich high in Iron.  assuming  the epidote to be metamorphosed limestone, the vesicles are easily accounted for by the escape of carbon dioxide.  Similarly the  andradite garnet, which is high in lime,relatively to the andesite  "11 is nore easily explained as a metamorphosed limestone than altered andesite.  The Pyroxene, however, may possibly have resulted from  either "by addition of material from the solutions.  If the veinlets  of Calcite,parallel to the Pyroxene crystals, are considered  res-  idual, the rock is metamorphosed limestone; if regarded as introduced either possibility remains.  The solid contact of the yyroxene and  Garnet is one such as would he expected if a thin limestone bed between two bands of andesite were folded togetiier, the high pressure produced locally by the folding, having caused flowage in the limestone, mineralization following and finding no obstructions such as gouge.  VThe contacts of the Pyroxene^ on the other hand,may have  originated by two beds of andesite  slipping slightly during the  if  process of folding andAsubsequent metamorphism giving rise to the pyroxene,but failing to sufficiently alter the gouge.  ITo residual  minerals,such as apatite, characteristic of the volcanics, were found in the pyroxene. Propylitization of the andesite probably commenced with the development of fractures,which acted as solution channels, and was evidently accompanied and followed by silicification nearer the intrusive, or^channols more directly connected with it.  The Iron  bearing minerals were in such oases altered to chlorite and -fyrite. No silicification was noticed away from well defined channels. The fault and its accompanying fold were formed by the advance of the intrusive|,as evidenced,first, by the fact that the solutions exuded by it followed the strudture mineralizing the adjacent rocks, and secondly, by the absence of fractures and the negligible development of cataclastic effects in the metamorphosked rock3.  "12" The fold and its fault are considered as genetically connected,as revealed by theArelations brought out in the diagram. She garnet, epidote, and pyroxeite must, therefore,have been formed between the time of formation of the fold ar.fi the crystallization of the diorite.  Quartz is among the latest of the gangue miner-  als, gxatacHty a product,  therefore, of a more advanced stage of  mineralization. The presence of pyrite as a probale alteration product in the volcanics would suggest that some of the pyrite associated witllh the pyroxene is dui to the alteration of the iron bearing minerals, and preceeded the expulsion of the materials from the intrusive givin rise to the metalliferous deposits. In the alteration of the rocks forming the anticlinal fold there are two possible courses th-t may have been followed by the solutions. First, they may have travelled ^long the axial plane of the fold and permeated the beds outward,or secondly, they may have followed the fault plane, each bed tapping this source.  In the  first case the process would be one of selective absorption due to chemical affinity rather than the alteration or beds of different composition; whereas in the second case, the latter explanation would seem to be more plausible.  The first theery is a possible explan-  ation but does not appear to lond itself as readily to the available evidence as does the second.  It is doubtful that Solutions from  the fold would penetrate the fault gouge and mineralize the rock beyond since gouge is so often found to he impermeable to solutions. The silicification of the hanging wall of the fault may then be considered as an indication thut the fault was  a  solution channel.  The hypothesis which most easily explains the alteration of the foot wall postulates a genetic  connection with there solutions.  lv-  It seems Inadvisable , therefore, tc place a great deal of emphasis upon the influence on the surrounding rocks of the solutions which  travelled along the axial zone of the fold,  On the other hand, the leached nature of the central member of the fold,now merely a black porous residue,indicates that some solutions actually have made use of that channel, but the-absence of siliceous matter suggests that the solutions were posterior to the formation of the minerals of the fold. Considering then,th^.t the fault and the folding took place prior to the advance of the intrusive to its present position relative to the deposit, and therefore, prior also to the contact metamorphic minerals of the fold, the conclusion follows that the formation of the pyroxene did not take place in the zone of rock flowage, since the limestone which had not flowed so at such a depth.  r  rould certainly have done  It is interesting to know that Koyes believes  (5)- - Keyes: Economic Geology : Vol IV: p^.go 265. Garnet Gontact Deposits. that the heavy anhydrous minerals formed well above the zone of rock flowage at the"San ledro '  copper deposits and neighbouring local-  ities. •BCOl^OiJLU G-^OLuGY.  ..'orkinfts.  The workings consist of  two prospect adits, one driven on the ore lead and the other parallel to it.  Tho former divides immediately inside the portal, one branc  striking S.5-0 E., for a distance of forty five feat,the latter strike N..75  B., for a distance of Shirty feet; a winze is sunk near the  end of this but was filled with water.She second  adit is about 50  feet north of the first and runs parallel to the apparent strike of the ore lead.  "14".  It follows the fault,strike due E.,for a distance of one hundred X feet, then crosscuts and feet.  icks up the ore following it for some 25  A winze was sunk hero alsofbut yielded nothing upon exam^n ore dunp of a few tovis of al lost solid sulphide gave  ination,  an idea of the material extracted. yniaftALQgy:  The ore consists of massive pyrrhot Lte .and pyrite  mixed with some c>alcopyrite and gangue; veins consisting of Chalcopyrite and pyrite and veins of pure pyrite cut the pyrrhotite. The gangue consists almost ./holly of metamorphosed country roukpyroxene - altering to chlorite,associated ;ith quartz w nd a little calcite; epidote was not fount i"1 the ore although associated with it.  The sulphides form over 75f' of the mass. Pyrrhotite is the most ahundent sulphide; it occurs in  massive form replacing the contact rock ard is itself cu1" and replaced "by the other sulphides. Pyrite is found in considerahle quantities  usually mix-  ed with some chalcopyrite; it is both massive and grahular often associate^ /ith quartz as <~ gangueJ in such cases it commonly forms small cubes.  . * .  Cho-lcopyrite^ore mineral of the distxic$,but is not found in large quantitie' on the Rainy DJ.J prospect.  lb occurs in small  veins associated with pyrite irre_"ularlj cutting the pyrrhotite. Assay results fmg*t»hgd(by the ovmer/are stated to have occasionally run quite high in copper,but to have averaged about 1$; the sulphur content ran about 30$.  "15" Except for a surface coating of limonite and a little copper carbonate the ores are unoxidized.  It is possible that they  were at one time enriched by supergene action but the i.iirnense amount of erosion "'rhich has taken place subsequent to Mineralization has removed all trace of it.  In any c:,se the extent of sec ndary enrich  ment would have been small as is usual in ores so abundant in pyrrhotite. PAIla.GEltfiCSIS:  Specimens of the ore were polished and studied  under the metallographic microscope; it was found that the earliest of the ore minerals introduced was pyrrhotite, which replaced most of the contact rock that it penetrated leaving small irregular masses of gangue as inclusions.  Pyrite folio ed the pyrrhotite v  replacing the gangue inclusions from the margins inward. fy),  process can he senn in vafcious stages ( Pigs: 6 &  This No  evidence was founl to indicate that up to this time any chalcopyrite had been introduced,but following the impregnation by pyrite and, perhaps,during it some of the ore*. >/era subjected to stresses. These stresses caused the pyrrhotite to flow ( Pig: S)  and the  pyriteVto fracture,resulting in the pjrrrhotite flowing between and around the pyrite grains as though introduced later (Pig: fr & %) • T^e gangue displays,with the pyrrhotite, typical flow structure apparently being of approximately the same hardness.  accompanying  the stresses therB was an introduction of chalcopyrite,which was forced to  follow the direction of minimum resistance, namely,  the courses occupied by the fractured pyrite; accordingly chalcopyrite UcS invariably associated with pyrite.  No persistent  veins of chalcopyrite were noticed and none was found associated  "16" witV unfracture"? pyrite, which go^s t  prove that tve oh-lcopyrlte  X I G , for the most part, lutor than the pyrite and aire later thun the commencement of the period of stress which fractured the py 5 to. CLA.SSIFI0o.TI0r a'TD COHCLUSLTS:  Deposits of this nature havo  been classified elsewhere as contact metamorphio rlepoeite „nd are of common occurrence.  The Rainy Day may be considered is a typical  example m± and inference relating to it nay be governed,to tome extent, by the observations raada on similar deposits in other districts.  The extreme irregularity of the boundaries of the mineral-  iaea areas is an outstanding feature of tho deposit.  It is difficul  therefore,if not impossible, to estimate the sixe with any degree of aoouracy, but available information indicates that it is similar in dimensions to other deposits in the district,  none of which have  justified operations on a large soale under present conditions. (6) Kemp states that the emissions,fro the inner part of an outwardly (6) J.F.Kemp: 3conon:ic Goology: Vo! : 7111 : 1915: page 597. chilled intrusive emergence.  favour loe^l channels rathor than the ^erseral  It may be assumed,therefore, that the Rainy Day and a  few other prospects located along tho s.T.e of the mineralized area.  dyke for' onl- _ portion  .71th this principle ir mind it if oiite  possible that if the deposits of the district wire ex.lotted ue a whole in order to bring the cost of operation down t.« a minimum, th.it they might he worked to yield a suitable return.  The owner expre::eo  the intention of utilising the sulphides as an ore ~f  sulphur, hut  it is doubtful that ores so high in pyrrhotite could compete for this purpose with the higher grade products of pure pyrite now on tho m market*  Pig: 1. Regional map of Henderson Lata.  jr•  „  •v S here Sljore  Imp  Line  S"i o r e  Line,  Fig:2. Showing the structure of the limestone and arriosite as expose-! or the eboraa of Hsrcter^on l^ke n^-r the diorito intrusive.  p^W^S  L » " W Material  „ .  1  rear  Fig: 8# Anticlinal Fold. Ulav-.tion)  .  y y  ^ ~ —— - y s>  y  y  N N  .  V  \  l'  ^s  x  >  y  "*  S-~-j ^o  '  \/<  y /  7  •-—'  "NJ  i  \  /  \_.—CT/ ' / 1/  "  )  1 ""-v. 1J O-a  \  y  * ' '  A.  3  Pig : 4. Crystallization in the garnet. A. Trapezohedron, B. Trapezohedron and Dodecahedron.  Fig : 5 ; Plow structure in tha -cyrrhotite, X fo»  Eifr 6 : P y r i t e r e p l a c i n g gangue along the contact with i y r r h o t i t e . The i n a i t i a l s t * g e . x Co  Fig f : The s&rne process shown i n Pig 5, more advanced. X/oo  \ /  X \  ,r  TH d-f /-\  c  j  «>7 ' \  "S I* \  i  V  ... C ^  'A '-.  '.  Uu  ~»,a irvtWn  •  •V  -k/ ./  fr: . h o t o Lororraph shc;;in? \ ~ r r h o t i t a ( e a r l i e r ) flonv-ig •oxmi f r a c t u r e d p y r i t e . Oh&lcopvrlta i s coxdraa pallor.', x / ' "  /*X  fffc&^^XFJf L4 ^ £•« >  a ^ M  -w-S'^ L-..J  Fig  : Another occurrence of the sane phenomena shov-m in ITiff 7 a f t e r the i n t r o d u c t i o n of chi-lcopyrits (fallow) t ^ ' i g s . 5 to 3 forii] a sxiita.j x/"C  9: *?iOto:.-icsro,rTiiph shoving • -vshutito ( o u r l i o r ) '21o •ovurl "r&ctnrod p y r i t o . Ohiileoy; r l t o i s c ^ o r - a d ;;ollo r . x/'"  P i f 9 : another occurrence of tho SU' .e phenor-.orju ahovm "'r: ?if? 7 i r ' t s r t'.i-j <r."t r o t a t i o n of -*\ loov- r-: * j '. , _ I o . ; } . t_^ L .t>. o t o 3 i*or... M . , . • . 1 ' , . fytoo  


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