"Science, Faculty of"@en . "Earth, Ocean and Atmospheric Sciences, Department of"@en . "DSpace"@en . "UBCV"@en . "Osborne, Freleigh Fitz"@en . "2009-07-15T22:28:40Z"@en . "1925"@en . "Master of Applied Science - MASc"@en . "University of British Columbia"@en . "[Abstract not available]"@en . "https://circle.library.ubc.ca/rest/handle/2429/10868?expand=metadata"@en . "47651749 bytes"@en . "application/pdf"@en . "HHEBKBW.-io- * \u00C2\u00AB \" * , , U.B.C. LIBRARY wattmrammemi //he Mao/7ehfe Occurrences oF the West Coast of ]/ct\"Couver /s-Und, \u00E2\u0080\u00A2& C / * W Contact M*i*-nnorbhism and 0r9 Genesis 0 ST \u00E2\u0080\u00A2S5 -~Fi.*rf 7 QUA TiA\"\u00C2\u00B0 \u00C2\u00AEOlO J PORT KYUQUOT @ Cfovrr/ pf//veg (2) p/}*&r A/yo So*\" /Z) 0S)tD &ACAF @ co#/&/y /F/YS/P 0/yt THE MAGNETITE OCCURRENCES OF THE WE8T COAST OF VANCOUVER ISLAND. B . 0 . ; THEIR CONTACT METAMORPHISM AND ORE GENESIS - By \u00E2\u0080\u0094 L R E L . E I G H \u00C2\u00A3 1 X 1 O S B O R N E \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 * * * . A THE3IS SUBMITTED FOR THE DEGREE OF MASTER OF APPLIED SCIENCE - In %M -DEPARTMENT OF GEOLOGY \u00E2\u0080\u00A2 * * * * T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A \u00E2\u0080\u0094I\u00E2\u0080\u0094\u00E2\u0080\u00A2\u00E2\u0080\u0094\u00C2\u00BB\u00E2\u0080\u0094\u00E2\u0080\u00A2\u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2^^\u00E2\u0080\u00A2 \u00E2\u0080\u00A2H l l l .H I .WPH ! \u00E2\u0080\u00A2 \u00C2\u00BB I \u00C2\u00BB APRIL 1 9 3 5 \u00E2\u0080\u00A2 ' \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 ' \u00E2\u0080\u00A2 ; \u00C2\u00BB * \u00C2\u00BB * * + THE MAGNETITE OCCURRENCES OF THE WEST COAST OF VANCOUVER ISLAND. B.C.; THEIR CONTACT METAMORPHISM AND ORE GENESIS 1. PREFACE IS) Acknowledgments. / Bibliography of Geology of West Coast. > -J*-3. SUMMARY AND CONCLUSIONS & -JT' 3. INTRODUCTION, (a) Physical features and geology of West Coast. _ -..-.-\u00E2\u0080\u0094 \u00E2\u0080\u0094 ..- \u00E2\u0080\u0094 -- A (b) Magnetite occurrences. -'-- 4-. (1) Situation and development. _ - - \u00E2\u0080\u0094 *\u00E2\u0080\u00A2\u00E2\u0080\u00A2 (\u00E2\u0080\u00A2; Topography of occurrences. - - - *\u00E2\u0080\u00A2 (3) Geology. - _ _ . . - _ \u00E2\u0080\u0094 - -5-. (c) Classification of deposits. __ - - -\u00C2\u00A3\u00E2\u0080\u00A2 (1) By types. _ - _ . . _ - - _ (S) By sounds. _ _ _ _ _ -4. DEPOSITS IN LIMESTONE ft! Endotheraiio effects of intrusion. Exothermic effects of intrusion. 5. DEPOSITS IN VANCOUVER VOLOAMIOS -[a) Copper Island. - -(b) Crown Prince. ,c) Darby and Joan. _ - -*\u00E2\u0080\u00A2 DEPOSITS IN LIMESTONE AND VOLCANICS 7. TIDEWATER AND JUNE ._ _ _ 8. MINERALOGY w Metallic Minerals - -II) Non-Metallic Minerals. 9-- -/\u00C2\u00A3>\u00E2\u0080\u00A2 - / / \u00E2\u0080\u00A2 . - , J. -/ 8. - /s>. 2. -2 . \" z * . 2S. ' 2 7-3 3 - + * 9. CONTACT METAMORPHISM (1) General. - ^ ^ (2) Formation of silicate zones on Vancouver ^ Island. (3) Relation of silicates and ore. _ _ _ - j - r 10. ORE DEPOSIT!QH -r\"c5' 81 Ore precipitat ion by l laes tone . \u00E2\u0080\u0094--*\u00E2\u0080\u00A2/ Ore precipitat ion by other than l i m e - ^ ^ stone* (5) Character of ore-bearing solut ions . e'e U . gUjOUBY OF THE TYPES OF MAOHETITE OCCURRENCES OF ^a^iW* 1 3 . BIBLIOfiBAPHY OF OOITAOT METAM0RPHI3M _ _ _ _ - 7 S - - LIST OF ILLUSTRATIONS - -Oatllne nap of West Coast. Showing location of properties. Frontpieoe. Sarita River and Sydney Inlet. To follow Page. i. Maiden Hair Fern, Elijah M.C. To follow Page ^ Magnetite - Conqueror M.C. and Head Bay. To follow Page 4-. Camera Luolda sketch from thin section. To follow Page / z. Camera Luclda drawing from polished surface. To follow Page ye. Magnetite Replacing Voloanlcs. To follow Page Leith, O.K. \u00C2\u00AB*-Mead, w.J. \"Metamorphic Geology\u00C2\u00BB 1915, p. 264. PLATE i U TO FOLLOW PAGE 4-. ' Maiden-hair -- E l i j ah lj\u00C2\u00BB-jugabgo C~reeK, * * # This illustrates the luxuriant growth found in some of the valleys. These ferns are growing on soil about four inches thick on the surface of weathered limestone at about 45\u00C2\u00B0. This shows the ease with which the surface may be covered by vegetation especially in moist places. PLATS I T . TO FOLLOW PAGE 4-Sf/H/jrermF ifa/y/yef = ^J / * Magnetite In Llaeetone Hootka Sound \u00E2\u0080\u00A2 Falle over Magnetite \u00E2\u0080\u0094 Outcrop Bugaboo Oreek. -Showing Limestone magnetite oontaot 5. INTRODUCTION on account of its hardness, homogeneity and resistance to weathering, especially when pure, so it stands out in relief against the common country rock, such as diorite and limestone. This characteristic results in the formation of prominent topographical features such as: steep bluffs, tops or caps of ridges and waterfalls in streams. The resistance of the mag-netite is so noticeable that a general statement may be made, that where ore-bodies are intersected by the present surface, some prominent topographical features will be present. It can toe seen that this conclusion has an important bearing on the probable continuation, on the surface, of exposed ore bodies. APPEARANCE OF THE ORE BODIES The pure magmetite, where exposed, has a characteristic steely blue colour, and usually shows a rather smooth surface. The normal colour may be obecured by a \"rusty\", that is llmonite, stain due to the decomposition of iron bearing sulphides or silicates. This rustiness is an important criterion for deter-mining the purity of the ore. A steely blue outcrop is not neoessarily a pure outcrop, because running water will remove the limonlte, or, in certain cases, the roots of the mosses may remove it. Under these conditions, where piteous magnetite is found, it may lie due to the removal of sulphides, silicates or calcite. 0 7We {v v ; , 6 IHTRODiJCTION All the ore occurrences examined belong to the con-tact metamorphic type, that is, they are due to the intrusion of the rocks of the Coast Range age into the rocks of the Vancouver group with consequent mineralization along the con-tact , usually confined to the intruded, but in some cases ex-tending into the intrusive reek as well. In most oases observed, the intrusive is a hornblende diorite. The deposits are divided Into a number of elaeeee which will be discussed la detail later. BOW TBS CONDITIONS OB VANCOUVER ISLAND AFFECT THE VALUE OF THE ORE A brief review of how the conditions on Vancouver Island affeet the value of the iron properties of the West Coast will be given. The first problem to be met is that of transportation; as stated before, most of the deposits are within three miles of navigable water, so if a short railroad or tramway were built to the shore, shipments oould be made by water* In order that the ore could be loaded, a harbour is necessary so the deposit must be on one of the sounds rather than on the open coast. Outside of the sounds severe storms are common from October to March, so it is doubtful if at all regular shipments oould be made by scow. Special barges might be used, but even then shipments might be hazardous and uncer-tain. Berkley Sound is the only sound at present connected to the East Coast by railroad, so ore mined on It might be shipped to Port Alberni, the railroad terminate, and then ?. mmmm transhipped. The ore from Gordon Elver, Bugaboo and Harris Creeks, might be shipped directly to Victoria, If a projected railroad were built. Zf ore were mined from any known occurrence on the West Coast, it would be a very expensive matter to market It due to its isolation* If a smelter were established there, essentially the same transportation problem would have to be met In taking in coal and taking out the manu-factured product* Sarkley Sound appears to be the only location which, at the present time, is at all feasible for such an undertaking* The climate Is such that mining operations could be carried on all the year around* The next condition to be considered is the geology. The deposits are all of the contact metamorphic type, one that Is noted for its Irregularity* This irregularity combined with the heavy soil mantle makes exploration difficult and expensive* Measurement of magnetic properties by the dip needle or magnetometer may be of value where the drift is thick, but they tell nothing of the quality Of the ore* The ore may be less valuable for a number of reasons. It may contain ex-cessive amounts of sulphides necessitating roasting, or sllloeons impurities may be present which makes special furnace treatment necessary. In some occurrences, copper minerals are found with the iron, where these are present in sufficient quantity it may pay to concentrate the ore and smelt the iron and copper separately. 8. 9LA39srt Head Bay 1 June '* OldSport 6LASS A A A | A 1 A A A A ' A 1 B 1 B 1 B 1 C ! c ! \u00C2\u00B0 ! \u00C2\u00B0> A ; o, ' C MAGNETITE DEVELOPED IN LIMESTONE 11. The oontact metamorphic deposits in limestone are the most common type and the one most noted in the literature* In general , the statement may be made that deposits in this rock have a tendency to be purer and more regular than those in other country rook* On the West Coast of Vancouver Island the claims that belong to this group are: Those on Gordon River, Bugaboo - Greek in the HiUnat limestone including; Rose, Little Bobs, 0 Baden Powell, Conqueror, Elijah and David; The Sarlta River claims also belong to the Nitinat limestone. The magnetite at Head Bay, Nootka Sound, occurs in the Sutton limestone and it le probable that the limestone of the claims on Harris Creek belong in it, but this is not certain. The intrusive responsible for mineralisation in this group is, in all cases observed, the Beale diorlte. The effects of the intrusion are of two kinds, the endothermic or changes in the intrusive; and the exothermic or changes in the limestone, due to the intrusive. 0 Clapp C.H. Geol. Surv. Can., Mem. 13, p. 189. ENDOTHERMIO EFFECTS In many oases, pronounced endothermlc changes are noted in the Intrusive. This effect is not confined to contacts with3 limestone, but is also found along contacts* with other rocks, although it is usually most markedly developed along the limestone oontacts. The most common change is a decrease in size of grain in the intrusive olose to the oontact. This is often, but not necessarily, accompanied by darker colour In the diorlte, due to 12 MAGNETITE IK LIMESTONE Endothermic EffectB a large increase in the content of dark ferromagneeian minerals. In some oases porphyritlo phases may represent the intrusive at the contact, and it is only by a consideration of the mineralogical composition and its field relations that its true nature can be ascertained. \"Solutions* derived from the magma of the diorite itself may cause an alteration of the intrusive* These can be divided inte two types, those which act before the magma is completely consolidated, and those acting after consolidation. The first case has not yet been fully worked out, so all the effects have not been described, but it seems probable that the formation of alteration products in feldspars, of \"injection perthites* and of typical contact metamorphlc minerals, a s ^ primary constituents of an igneous rock may be due to this. The alteration of plagioclase to more acid feldspars along the margins is probably also due to this action. To what extent this last stage alteration may be governed by the position of the contact is difficult to say, but it seems to have a marked influence in many cases. A detailed petrographical study of a suite of specimens from the intrusive close to a contact would probably throw some light, not only on theee last stage phenomena, but else on the nature of the magma and seae of the causes of contact metamorphism. The alteration after consolidation is represented by epldotization and sillcifloation in the diorite, often along joint oraoka. Occasionally garnet may be developed and magnetite may occur in the intrusive* 0 Pcflre \u00C2\u00A3 A-PLATE V. TO FOLLOW PAGE /2 Fig. A. Diorite^Conqueror M.O. showing formation of new plagioolaae (P) along the margins and within old altered feldspars (F). Where the new feldspar is close to the old For a dsscription of dlallage occurring under somewhat similar conditions BOO -Miller, W.J. - \"The Magnetic Iron-ores of Clinton Co. I.Y.* So. Geol. Vol. 14, pp. 514 - 533. See ftt*r\u00C2\u00A3 ~V 0 \u00C2\u00AB m: % 30. TIDEWATER teratione. . The next stage la a further formation of contact silicates so large masses of the rook are eventually replaced by garnet and epidote with miner amounts of diopside or hedenbergite. The period of metallization followed and probably to some sxtent overlapped it* The first metallic to be formed was magnetite, fol-lowing it bornits was deposited. Chalcopyrite was formed later than the bornite as seen both under the microscope and in the hand specimen. The order found in the case of the Tidewater is essentially the same as that found by Dolmage at the Marble Bay Mine, Texada Island. The bornite Is commonly replaced along joints and contact with ether minerals, by oovelllte and sometimes chalcocite. The alteration is only occasionally noted in the ehalcopyrlte and In no ease observed, was the alteration found along the contact of bornite and ehalcopyrlte, which, if the oovelllte were formed later than the ehalcopyrlte, would be a favourable place for it to form. The explanation that would seem to cover the case is that the copper sulphides, In par^,were formed before the deposition of the ehalcopyrlte but that some action extended beyond this time so a little of freshly deposited ehalcopyrlte was altered. The alteration of the limestone and andesite probably followed essentially the same order of,' formation of silicates, than metallisation but the ohange could not be worked out in as grsat detail. 0 Dolmage V* \"The Marble Bay Mine,Texada Island,B.O.M. So. Qeol. Vol. 16, PI. 12, p. 384. 31. TIDEWATER The complexity of the metamorphic process outlined above may be due to emanations from several intrueives below the ore-bodies. Endotheralc effects in the sills may account far some of the alteration in them. Tfg fpys finis Taa June or Jeune group of claims la about four \u00E2\u0080\u00A2ilea from Quatsino Sound. Liaeetones and volcanics have been Intruded by a dierite; a mere acid intrusive oocura near the claim and it probably la reeponeible fox many of the effects observed in the diorite, volcanics and limestone. The con-tact effecta on the volcanics are not extremely marked; some quarts, epidote and garnet are developed and they are miner-alised by magnetite and sulphides. The way In which the mag* netite replaces the volcanics, along strlngsrs and around graina la of interest beaouae it auggssts that the iron must have been introduced in very tenuous solutions or in some fora approaching a gas. Io vary exteneive mineralisation of the limestone was observed, but it was found to be largely replaced by clear, coarse grained quarts, resembling that of pegmatite dykes or igneous reeks. REPLACEMENT OF PIORITS The mast notable feature of thia deposit was a re-placement and mineralisation of the diorite. This process was noted in ether occurrences but net so extensively developed ae here. It followed some lines of weakness such as a joint oraok, so It can bs obeerved In all stages from a narrow line to one embracing large amounts of ths diorite. The first alteration JUNE GROUP is the introduction of magnetite vhloh, in most cases, replaces the ferroaagnesian constituents of the rook, although it is rarely found replacing feldspars. This replacement must have been by very tenuous solutions or by gases because of the preferential replacement of certain constituents, and due to the fact that en the polished surface no *lalbl\u00C2\u00BB connection Is visible between the magnetite masses. The basic plagio-olass is largely replaced by pyrite and pyrrhotite, in some cases tills replacement seems to have chosen alternate twinning lamellae In the feldspar. Bornite followed the Iron sulphides and some quartz veins observed were probably related to it. Covelllte and ohalcoclte are found in the bornite but in this oase they were not observed at all In the chalcopyrlte, so they were judged to have formed before the chalcopyrite, whloh was later than the bernite. Fine grained quartz with pyrite, in contrast to the clear, coarse grained quartz related to the bornite, cute all the ore minerals. Other non-metallic minerals include a dark-green, fine columnar epidote which appears as an alteration of the plagioclase, apparently follow-ing the formation of the pyrrhotite. Serpentine Is found in veins cutting the other minerals. It may be an alteration of the early minerals or of later introduction. The origin of the mineralizing solutions could not be worked out; whether they were from the diorlte Itself or the \u00E2\u0080\u00A2ere acid intrusive. It is peculiar that the diorlte should be replaced when ten feet away a limestone occurs, but it is probable that the limestone does not extend very far below the surfsow. MINERALOGY - METALLIC Before discussing the contact metamorphism, In general, the properties of the minerals found and peculiarities in them will be described so descriptions to use in the discussion of contact metamorphism and ore-genesis may be kept together* To determine the minerals present and their ages,\u00E2\u0080\u00A2 polished surfaces were prepared of over twenty-five pieces of characteristic ore. The general results will be summar-ised below under the particular mineral species. In the polishing of the ore, not much difficulty was experienced. The majority of the minerals in the section were hard, so that they could be ground to a good surface rapidly by means of a steel lap, using \"Wellsworth Emery No. 180\". It was found, that If little water were used, and the emery run until fairly dry, much better results could be obtained. After this treatment, It was put on another steel lap with \"Wellworth Emory No. 303*, and ground until all the scratches were re-moved. The polishing was carried on on a steel lap covered with fine linen, revolving at high speed. Chromic oxide mixed to a stiff paste with water or liquid soap was the polishing agent. The surface was held on this lap with con-siderable pressure until the lap was nearly dry, then a further application of the chromic oxide made* Most of the polishing 34. MIMSRALOGY - METALLIC Of the hard minerals took place when the lap was nearly dry and in this case the soap was of advantage because it dried more quickly on the lap. The specimens were mounted on glass slides with plasticine and examined under a Leitz mineral \u00C2\u00A9graphical microscope, fitted with a prism illuminator. . An qtc lamp with condensing lease was found useful for oblique illumination to supplement the vertical illuminator under medium power ob-jectives. By Means of the oblique Illumination, minerals which mould not be determined otherwise were easily made out, such as the nature of some of the gangue minerals. In the determination of the paragenesls of the minerals in the section, a constant difficulty was encountered, das to, not only the hard metallic minerals present, but also to the hard silicates, such as garnet, which tend to have idiomorphic form. VIth these minerals and softer ones in the same section there is a constant tendency for the softer ones to be called younger'. This probably accounts for the obscure time relations noted between pyrrhotite and magnetite. The commonest metallic mineral found in the deposits was magnetite. This mineral has the composition usually written T9s0f - H 5.5*6.5 G 5.2. It crystallises in the isometric system as octoheoVons and dodecahedrons. It is strongly magnetic and in some cases has polarity. In the surfaces from Vancouver Island magnetite is usually the oldest metallic mineral. I n general it is slightly later than the garnet 0 Gilbert 6. vThe Relation of Hardness to the Sequence of Ore Minerals* Ec. Geol. 7\u00C2\u00A91. 19, pp. 668-673. MIHERALQGY , METALLIC? minerals. The size of grain varies from some one-half inch aoross to some toe fine to see, and vlth difficulty distinguishable under the microscope. One difficult thing to account for ob-served under the microscope was the different appeamoe of grains. In the ease of the claims at Head Bay, Nootka Sound, in ons of ths small wins in limestone, the magnetite in the centre of the vein is much lighter than that at the two sides. No visible impurities oan be detected under the microscope. Adjacent grains of different oelors sight he accounted for by different optical orientation of the plane of too section, as an ootonedrar plane and a cubic plane but no apparent reason oan be found why, on opposite sides of a vein, a different orientation should hold from that In ths centre, the obvious explanation would be a slight change in the composition ef ths depositing solutions at the time of deposition. Broderiokf for a similar ease, but obssrvsd in adjacent grains of similar Orientation, comes to the conclusion that it may be due to a solid solution of Fe ZQ3 In F\u00C2\u00AB3 0t . In the Nootka Sound oaee there wae not much difference in the etch figures produosd on ths surface by hot hydrochloric aoid. Unfortunately accurate chemical analyses could not bs made. In a great number of cases, adjacent magnetite grains had a different color, but their orientation oould not^be drawn from them. In some cases these grains etched very differently with hot hydrochloric aoid. Ho titanium minerals were found either by etching or blowpipe tests. O Broderick T.M. \"Some of the Relations of Magnetite and Hematite.\" So. Oeol. Vol. XIV. 1919. p.363. 36. MINERALOGY - METALLIC In several places \"geniculated* magnetite was found. This type was named because of the resemblance to the geniculated twins of rutile. Examination of specimens failed to show any simple crystal face in the isometric system, which could form the twinnlng^lane so it was concluded the structure was not due to twinning. One explanation is that it was produced by inter-ference of individual crystals during growth, and the longitudinal furrows on the individual grains are due to the oscillatory com-bination of thus dodecahedron and the octohedron. The magnetite with polarity, constituting the variety lodestone is of Interest, because of its relative rarity. Two occurrences were noted on the West Coast. At the Sunshine group on Cascade Creek. Berkley Sound, magnetite with a strong polarity was found. At the Black Prince claim, about one mile from the above locality, more lodestone was founds its polarity was ' relatively weak. Pieces from both localities were polished and etched. The two magnetites were of totally different character. That from the Sunshine Group polished with a pitted surface. It was relatively pure with only a small amount of quartz later than the magnetite.thWt.% __. tended to have a somewhat parallel . arrangement throughout the surface. On etching, this surface showed a parallel arrangement of etched bands w>rh/renounced cracks v\u00E2\u0080\u00A2-:.\u00E2\u0080\u00A2:. etched deeper between them . , In one case, a radiating structure was observed, resembling that in specular!te, but no Ijematite could be found in the section. A similar structure was found in seme of the magnetite at Bead Bay even more highly dsveloped than this, but it showed no trace of polarity* The MINERALOGY * METALLIC speoimensfrom the Black Prince MUG. showed a mass of very pure magnetite consisting of grains from one-half a millimeter to one centimeter in diameter, intergrown with one another. Apparently when this magnetite was being formed, numerous centres of crystallization were set up so the equidimensional grains grew until they interfered with one another. The faces represented are, therefore, not crystal faces, but contact faces Under the microscope the grains appear different colors, and on etching the color,contrast is greater* Noganing Is observed within the grains. Specular!te or specular hematite occurs in several places. Under the microscope it shows needle like forms which are not as easily etched, by hot concentrated hydrochloric acid as the magnetite crystals. In all cases, where found, the hematite fojned later than the magnetite with needle like pro-jections cutting the grains of magnetite giving angular outlines to the pieces. For a somewhat similar occurrence, BrOderIck\u00C2\u00B0 or /arto otto (j rc/r-q / f> rfff * J , suggest these may be replacements of magnet!te\u00E2\u0080\u009E The relat ion to the sulphides i s not clear , except In the case of the Waterloo M.C. where the chaleopyrlte Is younger. In a l l cases the specularlte was formed by magmatic solutions or a l t e ra t ion . of ear l ie r magnetite under deep seated conditions. It could not be formed by weathering because ef the unoxidized condition of the sulphides near I t . Some of the hematite was s l ight ly magnetii'o but this i s probably dueto included magnetite. a> Br Oder i ok T.M, \"Some of the Relations of Magnetite and Hematite\" Ec. Geol. Vol. 14, 1919, p . 362. 38 MINERALOGY - METALLIC Pynhotite was found to be the most common sul-phide in the deposits. In certain cases it was found to son8titute practically the entire mineralization along the contact as at the small occurrence, described on Sarita River. On the polished surface, the mineral appeared as; veins in the magnetite and garnet, or as disseminated grains in them. These small grains never showed crystal boundaries and since they vera almost structureless as viewed under the microscope, it was very difficult to determine the relative ages of the pyrrhotite and the enclosing hard mineral. The hand specimens where the pyrrhotite occurred as stringers often proved mere valuable in telling the relative age than the polished surface. In general the conclusion arrived at was that the pyrrhotite was in most eases later than the magnetite. Fyrite occurred as stringers in the ore, as a 0 f i l l i n g for jo int cracks, and as disseminated grains with a strong idiomorphlc tendency. In some cases pyrite of several generations was found. The most usual occurrence was for i t to be ;just l a t s r than the pyrrhotite and occurring as veins in i t , however .when pyrrhotite did not occur pyrite often did, In which ease i t occurred as grains or veins in the magnetite and garae t i te . In some oases the pyrite occurred after ohalcapyrite associated with veins of oalolte or quarts; but I t wasmjore usual for i t to precede the copper iron sulphide. Chalcopyrite belonged to the l a s t stage of sulphide mineralization, except when small amounts of pyrite appear of la ter formation. Under the microscope this mineral i s easily recognised by i t s softness and color. I t i s almost & PL. ?}. PLATS 71. TO FOLLOW PAGE J<9 fiat A\u00C2\u00BB Camera lucida drawing of section from June. Mine, showing forms of pyrite (P) replacing pyrrhotite (M). The tendency to develop idiomorphic form is noticeable. The spherical structure seen in the two grains was noted in several places, hut It could not he explained* i x 2\u00C2\u00B0& Fig. B. June Mine. Magnetite (M) showing idiormorphlc form replacing calcite (C) interstitial to idiormorphlc grossularite (G). The magnetite is also replacing the garnet. MISERALOGY - METALLIC? u. 39. m\ w 4 . ,; If entirely structureless and seldom shows crystal forces, then usually against a soft mineral such ae calcite. In some eases where cut by later quarts veins the line of the veins shewed curious angular displacements suggesting a following of some structure as cleavage or parting, but since it is negative to the usual reagents, it was not etched. One peculiar Structure between magnetite and chalcopyrite was noted at the June group of claims. Here masses of magnetite were found which shewed in cress section, concentric elliptical bands of chalco-pyrite. The whole structure was about four Inches across the major axis. Under the microscope the chalcopyrite was seen to toe definitely later than the magnetite. The only explanation that would seem at all feasible is,that the magnetite was formed and then subjected to stress so concentric lines cf weakness I were formed. Later copper bearing solutions came along and |\u00C2\u00A7 took advantage of this to deposit. ||| m Bomite was found only in the two localities, namely |j the Tidewater and June. In both these localities it was definite-ly earlier than the chalcopjprite although at the June one occurrence suggested a later generation of bomite but the !|f m evidence was not conclusivs and it was met only in one place in |i one section. * |:|j Oovelllte and chalcocite were found ae primary minerals la the bornite. They occurred as small stringers and veins in the bomite, sometimes apparently parallel to the octohedral cleavage of that mineral. The evidence would point to the formation cf the coveliite and chalcocite, before the intro-duction of the chalcopyrite. > >!, * & * * * & * & : \u00E2\u0080\u00A2'-\u00E2\u0080\u00A2''\u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u00A2'-''\u00E2\u0080\u00A2 MINERALOGY - METALLIC Galena *as found as small cubes in toe altered line-atone at the June. The above Hat constitutes the primary metallic minerals observed in the magnetite occurrences. In general the average pangenesis of the minerals for all the deposits would be magnetise, pyrrhotite, pyrite, bornite, chalcopyrite. Lsoally there might be variations, but this list, except for the bornite, corresponds to Claps's'list for Southern Vancouver Island* 0 Olapp, C.H. Osol. Surv., Can,, Mem. 13, p. 168* MIKSRALOGY - mH-ti\u00C2\u00A3?klLIQ 41. In the case of the non-raetallies, the paragenesis tf mors difficult to dstannine because thin sections of the contact metamorphosed products weirs not asAlable. The identity of the transparent minerals was determined by in-spection and by the examination of powder in oil using Larsen's tables, A few were determined by their optical properties in thin section,where these were available. 0 Larsen E.3. \"The Microscopic Determination of the Nonopaque Minerals\" 0.S.G.S. Bull 679 - 1921. MIKERALOGY - SON-METALLIC 42. Garnet is present in the deposits both in massive and in crystal forms, showing the dodecahedron, and icosltetra-dron. The commonest form that occurs is the red calcium iron garnet, andradite. The calcium aluminium garnet, grossularite, occurs quite commonly but does not form as large bodies as the andradite. <4uite often the two minerals occur together and can only be separated under the microscope, by the different indices if refraction* The garntft does not show preference for any type of intruded rock, but apparently developed squally well in any of then* In general, garnet appeared to have been formed before the metallic minerals were deposited, but probably in \u00E2\u0080\u00A2est cases there was some overlapping in their time of formation. Epidote is another very common constituent in the com tact zone, occurring often intimately mixed with the magnetite. More often it occurs as an alteration of the volcanic rocks Invaded, often extending long distances from the contact. It ie quite often found as alteration of the Intrusive rook, especially almng fissures. Ho attempt was made to distinguish G> epidote formed by \"contact metamorphism*, and that formed later, \"as in fissure veins,n In the amphibole group actinolite and tremolite were found in some quite large crystals but they did not occur as plentifully as the epidote. Some hornblende may have been formed by contact metamorphlc process, but it was found impossible to distinguish between the product of Contact metamorphism and toe product of normal uralitization. 0 Lindgren 1. \u00E2\u0080\u00A2Metasomatic Processes in Fissure Veins* Tr. A.I.M.E. Vol . 30 , pp.610-611 - 1901 . few 43. MIHERALOGY - SOB-KJETALLIO In the pyroxene group several individuals were found* Diopslde is of quite common occurrence in the contact metamorphosed voleanics, but it Is quite easily overlooked in the field. In several localities a dark green mineral resembling dippside was found, probably hedenbergite or an intermediate mineral. So wollaatonite was observed but Dolmage reports some from the West Coast. Some vesuvianite was found under the microscope in a \u00E2\u0080\u00A2ass with epidote and quarts. Chlorite and serpentine were observed in a number of plaoes. They occurred later than the ore and in some oases are probably secondary, fotmdd by the alteration of earlier contact, silicates* Exaot relations of these were difficult to determine due to their softness and tendency to be removed during the polishing of surfaces. In several cases under the petrographlcal microscope small- grains of minerals thought to be clinosoisite or zoisite were found. On account of the high magnification required, it could not be distinguished whether the extinction was parallel or nearly so* Quarts is of very frequent occurrence in the deposits of * the Vest Coast* It is found in the masses of contact metamorphosed roes containing epidote and diopslde. It also occurs as veins cutting the ore in many of the deposits and is later than the majority of the mineralisation although it is occasionally found with pyrite. (D Dolmage f \u00C2\u00BBM. G.S.C* Sum. Rept. 1920 p. 15A 4 4 \u00E2\u0080\u00A2 SfilHERALOGY s NON-METALL?0 Calci te occurs as residual fragments of limestone in the contact metamorphosed rock and ore and a l s o as veins cut t ing the ore gone* Some c a l c i t e crys ta l s found were due to recent so lut ions and deposit ion from meteoric water. Titonite was observed in several s l i d e s of both the igneous rock and the contact metamorphosed product* Plagioclase near ol^oclase and more ac id was found as an a l t e r a t i o n product in some of the s l i d e s . The new feldspars seemed to he developed in the elder more bas ic ones A e t h e r by the replacement of the e ld feldspars bodily by the new ones, or by the removal of lime and addition of soda to the more basic ones. qopTAgT MgSMfiSaOgB - \u00C2\u00AB\"\u00C2\u00BB\u00E2\u0080\u00A2* Before discussing the contact metamorphism of the magnetite deposits It Is as well to review the existing ideas of this process and the definitions of the word. The word metamorphism Is, Itself, a much abused term; it has been defined by various authors with various applications so now, when metamorphism Is mentioned, the exact meaning of the author has to be judged from the context or from a definition. Contact metamorphism has also suffered from the usages imposed upon It* The definition adopted by probably the majority of geologists is. \"Contact metamorphism comprises all metamorphic changes due to contact with or proximity to any body of eruptive (igneous) rook, the new crystallizations not being definitely directed by dead weight stress.\" This definition is obviously intended to include the alteration, where materials are derived from the magma. Certain geologists would confine contact metamorphism to the effeote due to heat and mlneralisera without accession of material from the magma; , -~-~__zr55\u00C2\u00AB*&\u00C2\u00BB'i'*r'-'* \u00E2\u0080\u00A2\" \u00E2\u0080\u00A2 \"*\" \u00E2\u0080\u0094 ' \u00E2\u0080\u0094 - \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u0094 \" \" \" \u00E2\u0080\u0094 \"\u00E2\u0080\u00A2 * ....--this effect is usually, simply called recrystallization. The case where much material is contributed by the intrusive is oalled contact metasomatism. Barren further divides the metasomatio processes into, pneumatolytio and hydrothermal, depending whether the emanations are above or below the critical point for water\" vapour. Probably one reason for the confusion in the definitions of contact metamorphism and its phases, is the difficulty in determining which process* was the one most active, and so one 0 Daly R.A. \"Metamorphism and its Phases\". Bull, Oeol., Soo., of Am. Vol. 28, 1917 p, 405. ,f) Barrell, J. \"Geology of Marysvilie^Mining District Montana.\" U.S.G.S. Prof. Paper Ko. 57, pp.116-117, 1907. OOHTAOt METAMORPHISM e GENERAB term Is used to cover the several processes. In the same way, the distinction between pneumatolytic and hydrothermal alteration It very difficult to make so that, In many oases, these terms are used Interchangeably. mmsmmmm, There Is a disagreement among geologists as to the relatlTe Importance of the different processes of contact metamorphlsm. Recrystallizatlon, or the case where not much material has been Introduced from the magma, has been proved In a number of cases. By this process limestone is altered to marble and Shale to hornfels. The products of recrystallizatlon along igneous contacts are so similar to those which are due to the less severe regional metamorphlsm that It Is often difficult to separate the two effects. This may account for the overlooking of recrystallizatlon under conditions of contact metamorphlsm. Another reason for the overlooking of recrystallizatlon is that the alteration, by emanations from the intrusive, is usually much more striking and also due to the fact that they may replace or alter the recrystallized material. KAGfmq, gmmmsm The effect of Introduction of material from the magma Is usually so striking that all geologists must admit Its Importance In the formation of the contact zone. To discuss how the emanations from the magma arc given off to the contact zone, and the origin cf the mineral!zers it is necessary to follow the CONTACT METAMORPHISM \u00C2\u00BB SEKERAL changee In an intrusive from the molten atate to consolidation. If a normal magma is started with, it Is thought that it has a large quantity of gases associated with it auoh as; chlorine, water vapour, carbon dioxide, fluorine, sulphur, and other volatile eonetituente, which reduoe the fusion point of the melt and the viscosity. It is wall known that in the crystallization of igneous rocks the acoessory minerals, magnetite, pyrite, pyxrhotite, rutile, titanite, ilmenlte are the flrat to form. The flrat \u00C2\u00A9ryetallization of the metallica has always been difficult to explain becauae the same magma may form ore-bodies from ita mineralisers, as a laat product. Certain geologists? against the evidence of many petrographera, would even raverae the order of accessories first, and make them of later intro-duction by the mineral!zers. The processes advanced aa the moat prominent in the igneoua rook magma are; magmatic differentiation due to liquation and the principle of supersaturation abovs the amount necessary for the formation of entootles. To these may be added many minor processes which have been postulated for the formation of peculiar rook types. If the rigid principle of the formation of eutectics la hold, it la almost impossible to account for some igneoua rocks. \u00E2\u0080\u00A2a an example, a chip of a rock from Oliftan Point, Copper Island, 0 Tolman,G.F., and Rogers, A.F. *A study of the Magmatic Sulphide Ores.\" Stanford Univ. Publication 1916. pp. 30-31. Review Ec. Oeol. Vol. 13, pp.633-637. 48. CONTACT METAMORPHISM g GENERAL showed phenocrysts of quartz which was the first rock forming mineral to crystallise. Plagioelase phenocrysts were formed next, and the quarts was corroded and embayed and then a mioropegmatite which apparently altered the feldspar made up the groundmass. This case demonstrates how an eatectic may be passed and a mineral deposited whloh is unstable in the remainder of the magma* Vegt\u00C2\u00AE points out the tendency for the glass mal^ Lx of a reck to approach a eutectlc composition. This oscillation about eutootle omposition demonstrates how the \"enteotio* may not bo in equilibrium with the already deposited minerals whloh explains why a rook may be altered by its own \"eutootle juices.\u00E2\u0080\u00A2 Colonjrbelleves that the last \u00E2\u0080\u00A2tags residium, approaching a enteotic, may with the mineralizers produce important effects on the already formed minerals such as; the formation of \"injection perthites\", and the formation of aetinolite, bzotite, chlorite, at the expense of earlier ^erromagnesian minerals. Zn the case where the end stage product extends into the Intruded rock, its importance cannot be overlooked. This tendency toward the formation of eutectics would account for the rather notable tendency for the contact sones along different intruslvos to be rather similar, a faet which has boon urged by a number of supporters of the recrystalllsatlon hypothesis as a streng&rgument for similar impurities in the \u00C2\u00AE Vogt J.H.L. \"The Physical Chemistry of the Crystallization and Magmatio Differentiation if Igneous Rocks* Jour, of Geol. Vol.31,1922. pp.333-252 - pp.407-419. .\u00E2\u0080\u00A2-\u00E2\u0080\u009E This absorption^ of wall rook, especially limestone has been noted in many cases with the resulting production of peculiar rook types. It seems probable that this interaction would modify, to a large extent, the content of the mineral!zers and also cause their emanation to be somewhat irregular. The effect of the intrusive on the country rock Is usually so much more noticeable than the endothermic effects, that contact metarnorphism is often applied to this phase alone. After the magma is in place in the intruded rock, and as \u00E2\u0080\u00A2\u00C2\u00BB consolidation begins, a heat wave travels out; this wave in some oases, produces a recrystallizion, and a general readjustment of the country rock. It travels out slowly and the temperature Q) Paly ft.A. \"Genesis of the Alkaline Hocks. * Jour, of Geol. VOl. 26. pp.97*13*. \"Origin of the Alkaline Hocks.* Jour, of Geol. Vol. 21, pp.87*118. fe'iv 50. CONTACT METAMCHPHISM \u00C2\u00AB. GENERAL gradient is steep, so that before it has gravelled a long distanoe a considerable part of the intrusive haa consolidated, so there is a collecting of the last stage of crystallization product, and the miaeralisers which are released and enter the country rock. The reasons the intruded rather than the intrusive rook is attacked, are two, chemical and textural. The emanations are derived from the intrusive and as a result are more nearly in equilibrium with it, so they prefer to attack a rack of another composition. < ^ However, ae shown in the consideration of the processes in the Igneous reck, the mineralizes may not be in equilibrium with the Intrusive, and so it may be attacked. The texture of the Intrusive is usually close grained, while the country rook is relatively parous either, as an original character, or due to the heat wave from the intrusive. In individual deposits variation in the composition of the emanations may be traced by the order of deposition of the minerals. Ho rule seems to hold except that, in general the more acid emanations precede the more basic ones, but exceptions to this have bean noted raanjj: times, even in the one deposit. . On account of this variation in the contents of the emanations several authorsf especially those working on the iron-ores of Eastern United States, have postulated the differentiation of the last stage material and the mineraiizers into two poles, one aeid and one basic Aoeording to this view the more acid Q Colony R.J. 'Magnetite Iron Deposit of South Eastern New York\" Saw Tork State Museum Bulls* 349-250. 193$. 51. OOHTAQT METAKQRPHI8M g OBfflSRAL pole would represent a normal pegmatite, using it as the name of a product about as acid as a/granite, and the basic one would contain the iron and other basic metals. They use pegmatite also as a nans for the basic differ^tiate, which is unfortunate because it leads to confusion. In the case of the contact metamorphic magnetite there is not the striking evidence for differentiation of the mineralizere and the last stage residium into poles; but the two types seem to ooae off together. The reason why over-lapping of the solutions is common, will be discussed in connection with the contact metamorphism on Vancouver Island. 53< FORMATION OF SILICATE ZONE - VANCOUVER ISLAND OOKTACT M\u00C2\u00A3TAMQRPHI3M OH VANCOUVER ISLAND > FORMATION OF iJt. jt.. ,T.\u00E2\u0080\u009EMm.- *-iJC -TisJPl. ~ I M U In considering the contact metaraorphism of the magnetite occurrences of Vancouver Island, the type of field-work done must he borne in mind. A series of isolated occur-rences were examined} the purpose of the examination being mainly economic so the work was confined to a limited area close to the ore bodies* The lack of broad field work made it relative-ly impossible to determine the order of some of the processes on a broad field basis. Taking the occurrences all together, it is impossible to find \u00E2\u0080\u00A2widmnee of reorystalllsatloa without addition of material except In the ease of the limestone which was marmorised. this recryetalllzation may have been due to an earlier regional metamorphism, but In certain cases, a gradual increase in sise of grain as tfao intrusive contact is approached suggests, that al-though It may have been altered to marble by regional metamor-phism that it subsequently was recrystallised under the influence of the intruaove. The action of emanations from the magma is much more Important both as a contact metamorphosing agent and as the source of the metallic minerals of the contact zone. A noticeable feature of the deposits of the test Coast is the small size of the garnet sons formed. Xn many occurrences elsewhere, the garnet sons forms important rook unite in the contact deposits, along lntruslves of the same basicity as those of Vancouver Island. The only explanation that may be advanced ie that the magmas \u00E2\u0080\u00A2IS,. 53. FORMATION OF SILICATS ZONE - VANCOUVER ISLAND which produced the contact metamorphlsm were relatively high in iron hoaxing mineral!sera so the zone due to the more acid pa*?t waa not large. That some of the more aold products were present is shown by the formation of some silicates and the alteration of the basic feldspars of the intrusive to more acid forms along the margins and craoke. These emanations are characterised by their high content of, sodiums in some form, and of si Horn* The other common elements are also present, but they arm subordinate in amount to these in their effects. In the limestone contact tones ofVanoouver Island, minerals con-taining soda are relatively rare although soda lime feldspars0 are found in some oases, but in the contact zones of other form-ations the albite molecule is often noted. The reason for the small amount of soda in the limestone is that more stable compounds can be formed with the lime and iron, so the soda passes out and may reach the surface as sodium chloride which is often noted in fumarollc deposits. The deposits associated with the rocks of the Vancouver volcanlcs show fairly wide sones of alteration. The volcanlcs are of about the same basicity as the rooks which intrude them, so their alteration may bs very similar to that which goes on in the 9 igneous rocks. For this reason, the formation of more acid feld-spars at the expense of old ones in the contact metamorphism of the volcanlcs, i s ascribed to the same cause that produces the alteration In basicity of the feldspars in the intrusive, that I s , i t i s the result of the end stage products of the final consolidation \u00C2\u00A9 the zone of deposition, but duo to slower rate of diffusion the concentration cannot be maintained. So, until after the concentration of the chemically more active elements is reduced, there is no chance for the less active ones to deposit* It can be seen that with an easily A%aH*an S.Q.. U.S.G.8. Bul l . #312 - pp. 7-9. :i !i! RSUTIOH gg SILIOATgg TO MAGNETITE replaced rock such as limestone,that the effect on the siliceous emanations will be most rapid so they will, in general, form the silicated zone before the magnetite is deposited. This accords with the facts because in the deposits in limestone, there was a greater tendency to have the silicate definitely earlier than the magnetite. In the yolcanics the presence of silicates already in the contact sons may allow the magnetite to deposit before or contemporaneously, with sane of the silicates. By the Mass I\u00C2\u00BBaw the high concentration of silicates would tend to inhibit deposition of further silicates so even in the presence of the acid emanations magnetite might deposit. The later introduction of the magnetite may also be explained mechanically by this process. The acid emanations may i diffuse out, and then the magnetite solutions be deposited in another place or relatively wide solution channels may be established, so i t could paeess out by ordinary flew. i i 58. ORB DEPOSITION The ohemistry of the deposition of magnetite is dis-cussed following the discussion of the silicates, because of its general tendency to form later than they. As an intro-duction, a brief discussion of the chemical properties of magnetite is glean . In composition magnetite usually conforms to the general formula Fe ?0 4 er ferros\u00C2\u00A9 ferric oxide. As represented by the formula, magna tite contains 72.4$ iron, and 27.6# oxygen. It often differs from this theoretical value even when pure, due to Its ability to form solid solutions with ferric oxide, hematite. To quote from \"The Oxides of Iron,\" <\u00E2\u0080\u00A2 \"Ferrlo oxide (hematite) dissociates at high temperatures, giving off oxygen and leaving a homogeneous product which may be considered as a solid solution of magnetite, Fe^ 0? , In hematite (Fe2 0 ). The proportion of magnetite in the product depends upon the temperature and oxygen pres-sure above the oxides. The lower the oxygen pressure, and the higher the temperature, the more magnetite isfound in the solid solution. The reaction is strictly reversible for magnetite readily takes up oxygen at a temperature of 300\u00C2\u00B0 until the equilibrium proportion at the temperature in question is attained. Magnetite is therefore chemically unstable under atmospheric conditions, although it may remain unoxidized for long periods.* The melting point of magnetite is 153S\u00C2\u00B00 ., which is different from that of Doelter^who gives 1190\u00C2\u00B0- 1235\u00C2\u00B00 which is obviously too lev because magnetite formed on the lining of a copper con-verter is not melted at this temperature. % 0 \"The Oxides of Iron* The Carnegie Institution at Washington, Tear Book No. 15, 1916, p.137. \u00C2\u00AE Hodgeman and Large - \"Handbook of Chemistry and Physios\" \u00C2\u00AE\"Data of Geochemistry\" - U.S.O.A. Bull 695, p.287. 89. ORE PEPOSITIOg FORM OT IRON IN MINERALIZERS Just what form the iron is in in the magna is difficult 0 to say. The average composition of igneous rooks shows an excess of ferrous over ferric iron, and, therefore, probably much of the iron in the mineralixers is in the ferrous form. The for-mation of magnetite as an early product of crystallization in the magma shows the presence of the ferrous as well as ferric iron. The twojfclme\u00C2\u00A9 \u00C2\u00A9f formation for the iron oxides may be assumed to be due to iron in two forms in the magma; one of whioh forms the rook minerals, and the other goes into the mineralisers in some form. This is probably a ferrous or ferric fluoride \u00C2\u00A9r chloride or a mixture of them. The emanations are thought to be the iron halldea because these elements show strong \u00C2\u00A9hemioal affinity and are fairly stable. The halides are known to occur in the magma by the preseno* of minerals contaln-ing them, and they are also common in volcanic emanations. From the predominance of ferrous iron in the consolidated rook, some geologists\ave argued that the iron in the mineral!sers is in the ferrous form, and that the high ferric oxide content in the contact sone, le due to oxidation by limestone. Follow. Ing this explanation, one would expect that along Intrusive contacts with non calcareous sediment\u00C2\u00AE that the ratio of ferrous to ferric oxide would be greater than in the limestone contact sons. Th\u00C2\u00A9 composite straight-line diagrams of the changes in SmlliTan E.G. U.8.G.8. Bull #312, P.10. \u00C2\u00AE Winohell *\u00E2\u0080\u00A2\u00C2\u00BB\u00E2\u0080\u00A2 \u00E2\u0080\u00A2Petrographic Studies of Limestone Alteration at Bingham.\u00E2\u0080\u00A2 Trs. A.I.M.E. March, 1934. - ORE; DEPOSITION -ORE PRBCIPITATI08 BY LIMESTQHE 62. More data ie available for this reaction ae shown by the following ourve & J?/r\u00C2\u00A3ff\u00C2\u00A3rs &*\"***\u00C2\u00BB** At 806\u00C2\u00B0 only about 28$ 00 by volume le required to reduce the hematite. The ferric oxide would not be completely converted to the ferroue oxide, but the works of Soaman and Hosteller ehowa magnetite would form. Ae the curve shows, at 500\u00C2\u00B0 the maximum concentration of 00 le required to affeot the reduction of the ferrlo iron and since this le aleo below the temperature of the free formation of 00 by carbon,hematite is the most stable, so it is formed. The upper limit of temperature is more difficult to define. The critical points of many minerals in the contact sone have net been determined. One mineral which occurred In the contact deposits on Vancouver Island,tremollte3cannot form above 1000<> - noo\u00C2\u00B0 , so the probable temperature range ie from 1000\u00C2\u00B0 to 600\u00C2\u00B0 with a probable preference for the higher end Q Findlay - \"The Phase Rule and its applications\". P.309. \u00C2\u00AE 'The Oxides of Iron.\" \"The Dissociation of Hematite in Air\". Journ. Am. Oheau Soo. Vol. 38 pp.807*833\u00C2\u00BB1188-1198. Q Allen A Clement. Am. Journ. of So. 4th Series. Vol.26, p. 101. 1906. - ORE DEPOSITION -ORE PRECIPITATION BY LIMESTONE beeause, there, magnetite oan form most easily. Hematite forms close to 500\u00C2\u00B0 or lower. An attempt was made to find the conditions under which sulphides form, but no definite information could be found. Investigation of the sulphides, as of the iron oxides, hare net been made beeause they are not so important in iron blast furnace practicev. The only conclusion that could be drawn Is that pyrrhotite ,the ferrous sulphide,, oan form at a higher temperature than the ferrio sulphide, pyrite; and that in general, pyrite forme before ehaleopyrite. 64. - ORS DEPOSITION -PRE PRECIPITATION BY SILICATES The chemistry of the precipitation of magnetite by rocks, other than limestone, la not well understood. The only work la this branoh of the subject is on the precipitation Of minerals at low temperatures as related to agricultural chemistry, and the chemistry of secondary enrishment. This application of experiments carried on at low temperature to conditions of high, temperature may give results that are mis-leading. From the field evidence and the evidence of the mineralographical microsoope it is seen that iron bearing solutions do replace other than carbonate rocks and precipitate magnetite* If as before It is assumed that the iron is introduced at ferrous on ferric fluoride or chloride reactions to cause a precipitation may be worked out. Any one of thess salts is completely hydrolysed in water giving the corresponding hydroxide and the acid. The presence of a natural silicate with the alkali, or alkaline earth, metals hastens this precipitation, as shown by Sullivan^in several papers. The basts of the silicates are taken into solution and hydroxides oxides or silicates are precipitated depending on the strength of the base deposited. Sullivan's work was mainly on the copper salts but his experiments show that iron reacts similarly. \u00E2\u0080\u00A2\u00E2\u0080\u00A2'\" 0 Sullivan E.G. - \"The Interaction Between Minerals and %ter Solution.\" U.8.G.S. Bull 312. \"The Chemistry of Ore Deposition11. Kc. Geol. Vol. 1, pp.67-76. \"Experiments on theSeparation of the Constituents of a Solution by Filtration Through a Mineral Filter\". Be. Geol. Vol. 3, p.750. r t * * \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 # . \u00E2\u0080\u00A2 ' # I 65. - 8RE DEPOSITION -ORE PRECIPITATION BY SILICATES Some of the minerals which gave this e f fect are: feldspar, amphibole, augite , b iot i te ,garnet , veeuvianite and o l iv ine . Even quartz has the power of taking iron from ferr ic acetate so lut ions . At the high temperature at which the formation of the magnetite takes place i t may be supposed that the s i l i con l e f t w i l l be removed in solution and magnetite deposited espec ia l ly i f free fluorides are present. A reaction in -volving twrie chloride and a simple alkal i metal s i l i c a t e may be written: zFe Gljtz-R* Si QJ*JEZQ s z Fe (OR)3 w S i Oz^ uggests a very tenuous solution. 0 Clapp, O.H. Geol. Surv., Can. Mem. #13. - ORE DEPOSITION -^ \u00E2\u0080\u0094 ^ \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 * ~ * m \ in \u00E2\u0080\u00A2\u00E2\u0080\u00A2 I i \u00E2\u0080\u00A2 i M PHYSICAL CONDITIONS OF THE 80LUTI0NS AJ1 the polished surfaces from the different deposit* support the idea of tenuous solutions. Definite information regarding the temperature of formation of the silicates could not he found but it seems probable that they were derived from solutions the same temperature, or higher than that of the solutions producing the magnetite* The emanations producing the sllioation were juet as thin as thoee producing the magnetite as shown by their ease of diffusion, and the way in which they were observed to penetrate some of the minerals of the original rook as along oleatage planes in feldspars. 69. MAQSETITE QOOORHEHOES OF THE WORLD the writer made a brief review of some of the l i t e r -ature on the occurrences of magnetite the world over, to deter-mine the position of the contact metamorphic deposits as a source of ore. A brief summary of the geology of the more im-portant types and of some of the principal loca l i t i e s i s given, magnetite may be divided into two classes , o_ji the basis of i t s present commercial value, the t i taaiferous and the non~titaniferou\u00C2\u00AB e re . the t i taniferous ore i s not commercially valuable a t the present time, on account of the lack of an efficient method of \" reduotion, so the outline will be largely confined to the non-t i taniferous ore. USmm SB^EgatlO? TYPEf Magnetite i s a common accessory In igneous rocks of a l l bas ic i ty , so i t i s net remarkable that the segregation of material should produce ore-bodies. These are more common from bodies ef igneous reck corresponding in basici ty to a gabbro but a t a rule ,are t i tan l ferous . Exceptions have been noted where non-titaniferous magnetite occurs as a segregation, or t i t an -lferous magnetite i s of contact metamorphic origin. PEGMATITE TIPS* the nojtotitaniferoue magnetite formed by the oentrla-bution of iron, in eeme form from the magma, i s the most widely dis t r ibuted and the commercially most valuable source ef mag-a e t i t e as an ere of i ron. Hies divides these into* \u00E2\u0080\u0094 9~S3S. \u00C2\u00AEBatt\u00C2\u00AB\u00C2\u00BB\u00C2\u00BB W.8. \"The Magnetites of Horth Carolina - Their Origin.\" BO. Cool. Vol. 14 pp.509-635. \u00E2\u0084\u00A24\u00E2\u0080\u009E**.ftt. * \u00C2\u00AE Of out F.F. \"Mag****** lir^oUB * ** * M i n a 0 i o t a -I t . CteOl* Vol. 18, pp.2S3V269. 71. MAGNETITE OQCURREKOES QF THE WORLD \"PEGMATITE TYPE\" Leith provisionally classif ied the Atikokan magnetite and the deposit near Bathhurst N.B., in th is group. Throughout the whole group the resemblance to oontact metamorphlc ore bodies I s noticeable* The huge magnetite deposits of Lapland; Kiirunavaara, Luossavaara, Tolluvaara and Gelllvare are very di f f icul t to explain both on account of the i r huge size and their apparently unique features . Per Gel;}er%elieves the ore bodies represent a magmatlc product somewhat similar to the pegmatite type of Eastern United Sta tes . Daly believes the deposit i s a differ-ent iat ion In s i t u of a quartz porphyry. Gei^er's theory of the origin seems to be be t te r able to account for the facte especially the presence of apat i te in large amounts. Other occurrences havd been classed with these by Geijer including* Grangeberg l a Central Sweden, Solberg and Lyngrot in Southern Norway, and the Blagodat type of the Eastern Ural Mountains. The deposits of th i s group are few in number, and no fully satisfactory ex-planation of their origin has yet been given. Oontact raetamorphio deposits, or the specific ease where the mineralising solutions eome from an intrusive mass a and extend into and \u00E2\u0080\u00A2\u00E2\u0080\u00A2place another rock type with perhaps some replacement of the intrusive, as well, are common. The deposits 0Le i ta , O.K. \"The ir\u00C2\u00ABs* Ores of Panada*. - Jour. Canadian Mining I n s t i t u t e . Vol. 11, 1908, pp.94-95. \u00C2\u00A9Geijer Per. *\u00C2\u00AEome Problems in Iron Ore Geology in Sweden and AmsJtoa.\" Bo. Geol. Vol. 10, B P - f J - s a j . ^ ^ , fl s . \u00C2\u00A9Daly,R.A. \"Origin of Iron-Ores a t Klra*ma, Sweden. O.s.A. Traao. Vol. 26, p.99, 1915. 72. mmMMjmmmm s& \u00E2\u0084\u00A2 WORLD V COKTAOT METAMORPHIG nay be developed a t the con tacts of rook with intrdsives of any bas ic i ty but in the deposits important for their iron content there i s a tendency for the intrusive to be of medium bas io i ty . Due to lack of uniformity in rock nomenclature and to the use of \"granite* for any, l ight colored, plutonie rook an exact comparison of the basici ty in the intruslves could not be made. According to the l i t e ra tu re contact, deposits may be found along rocks such as granite, monzonite, quartz-monzonite, but there la a tendency for more of the iron ores to be found along contacts of granodiorite, quartz d i e r i t e , d ior i te and the i r porpbyritlc equivalents* All the contact metamorphic ore-bodies are noted for their i r regu la r i ty , both in the d i s -t r ibut ion of ere and the gangue contact s i l i oa tee . The ore i e commonly mixed with eueh amounts of Iron or copper iron sulphides that i t often requires roasting before use. These \u00C2\u00A9res are of such wide distr ibution that a l l the occurrences cannot be l i s t ed but a few of the more important type looa l i t iee will be mentioned. The distr ibution of the contact metamorphic deposits in America i s so s t r ik ing that Eckel \u00C2\u00AEsays; \"We might summarise the matter by saying that almost every known Iron deposit along the Pacific Coast, from Alaska to Soutbem Chile, and from the coast back to* the eastern-most mountain range, f a l l s into the class of deposits.\" eSeke l , B.C. \"Iron Ores Their Occurrence Valuation and CentrelS 19** P\u00C2\u00BB87. MAGNETITE 0CCURRSM0S8 Of THE WORLD CONTACT METAMORPHIO Theee relatione are true in general, but exoeptlone say be noted. The more important localities in the United Statee are: Iron Springe /Utah; The Barth IroiPoree; The magnet!tee of Shasta Co., California; and the occurrenoe near Fairvlew I.lf., and Dillsbux?, York Co?, Pa. Many smaller depoelte might be added to the liet. In Canada many contact meteporphio depoelte are found eepeoially in the feet. Among the best known ones are thoee of Texada Island. In Eastern Canada, eepeoially Ontario contaot deposits are commonly found. Outside of United Statee and Canada, many contact metamorphio iron ore depoelte are known. In the following oo-eurenoee noted the information wae obtained from \"Iron Ore Re-eouroee of the World\", publiehed by the International Oeologioal 4Leith,O.K. a Harder, E.O. U.3.G.3. Bull 338. z Jones, J.O. \"The Barth Iron Ore Occurrenoe\" Ec. Oeol.VOL. 8, pp.247. 3 Presoott Baeil - \"Mgte ore of Shaota Co. Calif.\" So. Oeol. Vol. 3, p.465. L* Smythe, D.D. - \"A contaot metamorphic Iron Ore Depoeit Near Fairrlew I.M.\" Ec.Ocol. Vol. 16, pp.410. ^Harder,K.O. - \"Structure and origin of the Magnetite Depoelte near Oillabuxy York Co. Pa.\" So. Gaol. Yoli.8, pp. 599-623, 1910. <\u00C2\u00A3 MoOonnell, R.O. \"Oeol. 3urr. Can. Mem. #58, 1914. d*epe S.J. - \"InTeetigntion of \u00C2\u00AB*g\u00C2\u00BBotic Iron oree froaEeetern Ontario\". A.I.M.S. Tr. Vol. 29, pp.373-405 - 1900. \"Report of Ontario Iron Ore Committee! Toronto 1923 Appendix. 74. MAGNETITE , OCTREES PESf OF JHE WORLD CONTACT METAMQRPHIC Congress of 1910, Stockholm. Magnetite occurs in a zone apparently extending south from Mexico into Peru* In Mexico the deposits are in limestone, where it has been intruded by diorite, monsenite, porphyrite, and granite. In Cuba, impor-tant deposits are found in limestone due to the intrusion of diorite. Outside of America, important occurrences of contact metamorphic ore bodies are known in Sweden, Russia, Hungary. Japan,Australia, and China. Many other countries have this type of deposit, indeed they seem to occur almost anywhere where there is extensive igneous intrusion and not too great a removal of the contact zone by erosion. \u00E2\u0080\u00A2MM* ,yoM\u00C2\u00BBMq|\u00C2\u00AB, * Magnetite formed by the contact metamorphism of iron formation in the Pre Cambrian rocks is of rather M common occurrence in areas of extensive igneous intrusive\". It is possible that some magnetite may be formed by regional meta-morphism, but it is more common under conditions of contact metamorphlam. The ore of thie type is, as a rule, rather impure due to an excessive amount of eliiceous impuritiee in the form of quartz, amphibole and other silicates. In Eastern North ^ America there are a large number of deposits belonging to thie type. They are found in Sweden, Norway, Brazil and South Africa, 0Papers by Xepp, Lindgren, Ross and others. A.I.M.S. ?*jns. 56. 1916 \u00E2\u0080\u00A2 78. MAGNETITE OCCURRENCES OF THE WORLD IRQK FORMATION Grout\u00C2\u00AEcomes to the conclusion that due to the Intrusion of a gabbro, the magnetite formed in the Gunflint formation was fused; hut his melting point is two to three hundred degrees too low* Occurrences of black sand are fairly common but not, at present, of commercial value* These deposits are derived by the concentration of accessory minerals, or of other raag-netite occurrences. Often where the magnetite^fcrmf large bodies, they are titaniferous. An occurrence of interest from its peculiarity rather than Its commercial importance is that found about a fumarole^ the magnatite occurs as octohedra, lining a vent in the pumice. The purity of the.pumice precludes the possibility of the derivation of the iron from it so the magnetite must have been deposited by emanation from the fumarole under conditions of low oxygen pressure and rather high temperature. A notable feature was the occurrence of halite on the faces of, and intergrown with the octohedra of magnetite. Floor!te was also found in considerable quantities by analysis. Magnetite in all Its occurrences is formed at high tem-perature either as a direct product of the magma or due to the aetamorphic effects of the magna on previously existing iron minerals. The wide areas of igneous activity favour the production & Grout, F.F. Be. Geol. Vol. 18, p. 353. ^\"ramarolio Incrustations in the Valley of Ten Thousand Smokes.\" Geophysical Laboratory- Wash. #541, by E.G. Zies. 76. MAGNETITE 00CURREHCE3 OF THE WORLD IRON FQRMA.TIOy of magnetite, while conditions of weathering favour the pro-duction of the higher oxides and hydrates. OOMMEROIAL VALUE OF MAGNETITE An attempt was made to determine the proportion of magnetite, used as a source of iron, derived from contact metaraorphic deposits. More than general resul ts could not be obtained because i f the s t a t i s t i c s are available, the ore i s not separated In to the types, or if the amount of magnetite l a l i s t e d theloeal i t lee where I t was mined are not given, so the geology of the deposits cannot be found. Figures for United States^show that of a to ta l production |>f Iron-ore, for the year 1923, of 09,351,442 tons, that 2,190,624 tons, or 3.16$ \u00C2\u00A9f the to t a l ore produced was magnetite. Of mines producing over 100,000,,tons,*r 1.2> of the to ta l ^ frem contact metamorphic deposits, the remainder being from the magnetite type of the Eastern U.S. From the rem/alnder of the smaller producers^, no figures are avai lable, but from the distr ibution of the loca l i t i e s i t seems probable that about 11$ Is from contaot metamorphic deposits, and t h a i par t of th is production i s iised as f lux. In Canada? the iron ore produced in 1933 was 20,739 tons, and the principal par t of th is was magnetite from Moose Mountain? Ontario. O \"Mineral Resources of the United States 1923.\" Pt . 1 pp.295-329. Advance chapter. \u00C2\u00AE \"Mineral Production of Canada 1933* Bureau of S ta t i s t i cs 1924. MAGNET!T3? OCCUKRSHCSS OF THE WORLD COMMERCIAL VAOT OF MAGBSHTE In Sweden with a production of 5,597,707 tons of iron \u00C2\u00A9re in 1933 the larger part \u00E2\u0080\u00A2 probably 85$, is magnetite produced from the Lapland type of deposit and a small amount of ere from the contact deposits. Among $he smaller producers of Iron ore, it is probable that contact metamorphic magnetite is more important than in the tin!ted States. An instances of this is Japan, where magnetite from contact deposits is mined for use in the blast furnace. The tendency at present seems to be *ft use easily available hematite as an ore, and to only use magnetite to form a mixture with the other ore. Doubtless, as the easily available high grade hematite bodes become depleted, the smaller contact metamorphic ore bodies will become more valuable as \u00E2\u0080\u00A2 source of iron, but at presentt they are rather minor producers\u00E2\u0080\u00A2 \u00E2\u0080\u00A2Skandinavlska Kre&itacktiebolaget.* Stockholm, Quarterly Rept. Jan. 1985. The following is a short bibliography of contact metamorphism. In many places, references to contact metamor-phism may be found, but in those given below, a general treat* ment of the subject is given, or some feature is emphasised. Bain, G.W. \"Almandite and its significanee in the contact Zones of the Grenville Limestone.1* Jour, of Geol. Vol. 31, 1933. pp.650-668. (Gneisses formed by the contact metamorphism of limestone) jjggtyUJU \"Pbysieal Effects of Contact Metamorphism.* Am. Jour. 8c. 1902. pp. 279-296. Barrel!, J. \"Geology of the Marysville Mining District, Montana.* U.3.G.S. Prof. Paper 57. Brocfc. R.W. \"A British Columbia Example of the Contact Metamorphism of a Granite to a Garnet.\" R. Soc. Can., Tr. (3) 9. IV. pp.175-180, Butler. B.S. \u00C2\u00BBA Suggested Explanation of the High Ferrio Oxide content of Limestone Contact Zones.\" Eo. Geol. Vol. 18, pp. 398-405. Clements. J.M. \"A Contribution to the Study of Contact Me tamorphlsm\u00E2\u0080\u00A2\" Am. Jr. So. (4), Vol. 7. pp.81-91. 1899. (Suggests transfer of Na silicate from intrusive to contact zone.) B I B L I O G R A P H Y ismJhh \"Ore Deposits at the Contact of Intrusive Rocks and Limestone.* So. Geol. Vol. 3. p. 1. 1907. ujk\u00C2\u00A3\u00C2\u00AB * Contact Deposits\" Mining Scientific Press 103. pp.678-681. 1911. Harder. E.G. \"The Iron Ores of Western and Central California.* U.3.G.3. Bull 430. 1909. \"3hap Granite and Associated Rooks.\u00E2\u0080\u00A2 Jhap Quat. Jour* of Geol* Boo. of Lon. Vol. 47 * 1891. p . 268. ftflth, q.K. & Harder.S.q. \"The Iron Ores of the Iron Springs Dis t r ic t , Utah.* U.S.G.S. Bull 338, 1908. Llnderen. W. \"The Character and Genesis ofOertaln Con-tac t Deposits.\" Trans* A.I.M.E. Vol. 31, 1902. p . 698. hiMm&JL \"Copper Deposits of Clifton Morenci Dis-t r i c t Ar izona , \" . U.S.G.S. Prof. Paper 43, 1905. ?TfSOO^t B. \"Boats Observations on Contact Hetamorphic Ore Deposits.* So* Geol.Vol. 10, 1915. p .55. ! I \u00C2\u00A7 . k L O \u00C2\u00A3 R A P H Y 8purrt Qarr,eyand Fenner \"Study of a contact metamorphic Ore Deposit. The Dolores Mine at Matehuala Srt.P. Mexico. Ic. Geol.Vol. 7. p. 444. \"The Copper Deposits e\u00C2\u00A3 the Velardena District, Durango, Mexico. '\u00E2\u0080\u00A2 E c Geol. Vol. I l l* p. 688. teed. W\u00C2\u00ABH\u00C2\u00BB \"Ore Deposits near Igneous Contacts.\" Trans.A.I .M.S. Vol. 33 , 1903. pp. 715*746. Geology and Ore Deposits of the MaoXay Region Idaho\". 0.3.0.3. Prof. Paper 97. (Reviews questions to be answered in a contact net. deposit development of garnet in growth.) Uglow. W.L. \"A Review of theExiating Hypotheses on the Origin of the Secondary Silicate Zonee at the Contact of Limestone with the Intrusive.\" Be. Geol. Vol. 8, pp. 19.50. \u00C2\u00BB 315-234. "@en . "Thesis/Dissertation"@en . "1925-05"@en . "10.14288/1.0052717"@en . "eng"@en . "Geological Sciences"@en . "Vancouver : University of British Columbia Library"@en . "University of British Columbia"@en . "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en . "Graduate"@en . "The magnetite occurrences of the West coast of Vancouver Island, B.C. : their contact metamorphism and ore genesis"@en . "Text"@en . "http://hdl.handle.net/2429/10868"@en .