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By P. J. Deveaux, M. J. Kreczmer

The Tartan Lake deposit 12 km northeast of Flin Flon, Manitoba, was discovered in March of 1984 during the investigation of a VLF anomaly. The discovery hole intersected 16.83 metres averaging 21 gm Au/tonne. Since then, 99 holes, over 21,000 metres, have been drilled outlining 419,491 tonnes grading 11.79 gm Au/tonne in a di stinct group of mineralized lenses referred to as the Main Zone. Three other mineralized zones are known on the property but no reserves have been allowed for these, the South , East and Base Line zones. The Main Zone consists of seven parallel, east-west striking, quartz lenses. The lenses dip steeply to the north and plunge steeply west to northwest. Lens number l strikes for 160m and extends vertically to the 90m level. Within th is lens there is a 60m interval of low grade materi al. Lens number 2 is located about 5-l0m within the foo twall of Lens number I. Near surface this lens stri kes for 40m, at 200m level the strike length increases to 200 m. To date the deepest mineralization on Lens 2 has been intersected at a vert ical depth of 527m. Five smaller lenses are located in the foo twall of Lens 2 , containing gold va lues similar to the two main lenses but erratically distributed. The South Zone, located 100m south of the Main Zone, strikes east-west fo r l00m above the 100m level. The East Zone, found 230m east of the Main Zone, strikes fo r 80m and may possibly be an ex tension of the South Zone. The Base Line Zone is located 275m south of the Main Zone. Sporadic, but very significant gold intersections have been obta ined1n all three zones. Gold-bearing quartz-ca rbonate tourmaline veins are generally confined to a silicous crystal tu ff hori zon. The crystal tuff exhi bits fi ve distinct types of alteration: silicification, sericitization, ca rbonati zation, chlorit ization and pyritization. Silicification has resulted in a perasive addition of silica and the generation of multiple quartz veins. Sericiti zation is restricted to the crystal tuff. All rock units are pervasively carbonatized . Ankerite is abundant in the quartz veins and within the shear zones, particul arly those located along the chilled margin of a nearby gabbro-diorite intrusion. Chloritization is widely spread th roughout the rock units, while pyritization fo rms a broad alteration halo associated with the orebody. Sulphide accesso ry minerals associated with the gold , whi ch fo r the most part appears to be free, are chalcopyrite and pyrite. Generally, the higher grade gold values are related to an increased content of sulphides in the qua rtz veins. The average sulphide content in the deposit is less than 5 %.

Jan 1, 1986

By Brian W. Mackenzie

The paper addresses five questions concerning the economic of gold exploration in the western Canadian shield. Can historical footprints be used to project future gold prices for exploration planning? Experience suggests that gold price forecast are too clo ely tied to current market events to provide meaningful guidelines. What range of breakeven gold price will typically be required to ju tify gold exploration in Canada? Minimum price requirements. initially asses ed at $540 to $1080 per ounce, probably lie in the range of $480 to $760 per ounce (expressed in 1985 Canadian dollar). Within Canada, what role do regional conditions and taxation policies play in determining the viability of prospective gold exploration targets? Striking interprovincial differences are found to exist, given the same geological circum tance -Nova Scotia, ew Brunswick, and Quebec rank towards the top in term of motivating exploration, Briti h Columbia provides the least investment incentive, while Saskatchewan and Manitoba place around the middle of the Canadian league. How can minimum acceptable tonnage-grade conditions for gold targets in the western shield be established and, then, constructively applied to provide exploration planning guidelines? Minimum target conditions, realis tically defined in terms of a broad band of doubt, can be used judiciously to help balance the direct costs of uneconomic exploration with the opportunity costs associated with rejecting economic deposits. How does the average cost per ounce of gold discovered in the western shield compare with the overall Canadian experience? Average discovery costs for the we tern shield, apprai ed at $100 per ounce, are shown to compare favourably with the Canada-wide record.

Jan 1, 1986

By D. V. Ziehlke, J. M. Franklin, T. M. Gordon, A. G. Galley

The Snow Lake-Wekusko Lake region of northern Manitoba conta ins numerous lode gold occurrences, including the largest gold deposit in the Churchill Prov ince, the Nor Acme mine. The Aphebian volcanic and sedimentary rocks of this region are comprised of submarine volcanic strata, overlain by turbidites, both of the Amisk Group, and fluvi atile sedimenta ry strata and bimodally composed subaerial volcanic rocks of the overlying Missi Group. Gold occurs as: 1) accessory gold in volcanogenic massive sulphide deposits, 2) lode gold in shear zones related to sy n- to post-FI thrust fa ults, and 3) lode-gold associated with post-F2 fault . An alteration a emblage of biotite, al bite and calc ite is associated with both groups of lode-gold deposits, and has been superimposed on the regionall y-developed metamorphic assemblages. AJthough these deposi ts are spatial ly related to britt le-ductile faul ts of different initial ages, they appear to have all fo rmed after the major period of reg ional fo lding and metamorphism, and thus may be penecontemporaneous. The alteration is different from the sericite-ankerite-quartz assemblage that is typically associated with gold deposits in Superio r Prov ince. Deposits in thi s area of Churchill Prov ince may have formed either at a higher temperature or a deeper structu ra l level than tho e in Superior Prov ince.

Jan 1, 1986

By W. A. Padgham, H. Helmstaedt

Field evidence for current hypothe e about age and kinematic ignificance of gold-bearing hear zones in the Archean Yellowkni fe greenstone belt is reviewed , and it is concluded that major disagreements between previous workers are a direct result of differences in stratigraphic and tructural in terpretations of the Yellowknife Supergroup. Although goldbearing hear zone appear to be confined to the mafic volcanic pile of the Kam Group. it can be shown that shearing affected all supracru tal rocks, including the Jackson Lake Formation. now con idered to represent the youngest unit of the Yellowknife Supergroup. tructural ob ervations are incompatible with the hypothe is that the hear zones represent loci of ynvolcanic gravity sliding but are consistent with earlier conclu ions that shear zone development commenced with rotation of the volcanic pile and continued as re ult of lateral shortening broadly overlapping with the emplacement of granitoid batholiths. Shear Zones are common throughout the entire green tone belt. yet productive zone are confined to the Yellowknife Bay Formation of the Kam Group and localized where flow abut with a high angle again t the contact of the We tern Plutonic complex. However. no obvious tructural and lithological features have been recognized that are more favorable for gold deposition and distinguish the shear zones and flows of the area around the mines from those of other parts of the greenstone belt. The model that gold wa transported by metamorphic solutions and that hear zones were the firs t-order control for gold deposition provides no explanation for the trong localization of the depo it . As porphyries with elevated gold contents are present in and near ome of the mines. the possibility that gold was deposited from hydrothermal system around fel ic intrusion representing early phases of the Western Plutonic complex should be given erious consideration.

Jan 1, 1986

By Janet S. Springer

Anomalous gold concentrations in carbonaceous material have given rise to misconceptions about the role of carbon in gold depo its. Some hydrocarbon and carbon-rich black muds may how gold contents raised to 100 time above background by mechanical entrapment. urface effect in fine ediments. and metabolic fixing of gold by micro-organisms. Such concentrates, however, are 10 times too low to be economic. Studie in the Archean of Ontario show that graphite schi t are not the protore to an economically workable gold deposit. A later event of gold introduction ha been uperimposed on the initial low concentrations. Gold enrichment i localized by reduction at vein margins where hear plane . the conduits of mineralization, cut carbonaceou horizons.

Jan 1, 1986

By Gordon Nelson

The Homestake gold mine is one of the largest and oldest continuously operating gold mines in orth Ame rica. To date this mine has produced in excess of 128.000.000 tons of ore containing almost 34 million ounces of gold . Gold mine ralization is restricted to the Homestake Formation. This unit is a metamorphosed iron-formation which is enclosed by pellitic metasedime nts below (Poorman Formation) and a pellitic to qua rt zitic unit (Elli son Formation) above. The e ntire Precambrian sequence. in the Lead area. has been subjected to a multi-stage defo rmation episode which ha c reated an extremely complex structural setting for the Homestake orebodies. Metamorphic grade inc reases from greenschi st ro amphibolite in a northeast d irecti on acros the mine area. Present thickness of the Home take fo rmation va ric from O to »400 fee t. The amount of thicke ning and th inning which is attributable to tectonic deformation or original sedimenta ry di fferences is not known. Orebodies constitute onl y a small pe rcentage of the Homestake Formation and do not occur along a pa rticul ar stratigraphic pos ition within the unit. Gold i assoc iated with inc reased py rrhotite and a rsenopyrite concentrations within the iron formation. Inc reased \ cin qua rt z development and chl oritic alteration usuall y accompany this minerali zation. Local remobilizati on of mine ralization due to metamorphi sm has occurred. Homestake mine ralization has been shown to be of sy ngeneti c origin . Because no feeder zones have yet been recognized a di stal source for the mine ralization is inferred .

Jan 1, 1986

By S. Averill, B. Schreiner, V. Sopuck

The La Ronge. Kisseynew, Glennie Lake and Flin Flon domains. the main focu for gold exploration in the southeast part of the Saskatchewan Shield, were subject to continental glacial ice advances from the northeast during the Quaternary. Based on forty-four auger hole along with surficial mapping, the general Quaternary stratigraphy in this area is observed to be composed of a lower till unit , an overlying stratified unit of glaciofluvial sand and gravel and/or a glaciolacustrine silt-clay unit. an upper till. and an upper tratified unit. The lower till is commonly found throughout the geological domains except where it has been eroded in glaciofluvial or fluvial channels. Glacial Lake Agassiz fo rmerly covered most of these prospective domains. The lacustrine deposits associated with the lake impede surficial geochemical surveys including soil. lake sediment. and biogeochemical surveys. The approximate extent of clay cover can be predicted from beach elevations. For instance. in the Waddy Lake area. clay i not known to occur above about 1,400 feet (425 m) elevation. Exploration techniques are hampered by clay in at least one third of the volcanic belt. Thi s influence is indicated by the fact that nearly all gold prospect found to date are located above 1,400 feet (425 m) while the area of clay cover is vi rtually unexplored. The upper till i related to a minor ice readvance. This till is the medium often sampled during soil surveys in the area . lts value as a geochemical ampling medium is dependent on the extent of erosional contact with bedrock highs on the lower till. Those areas which are relatively free of lacustrine and fluvial deposits are those where surface geochemical methods work best. In the Waddy Lake volcanic belt approximately 25-50% of the area may be suitable for surficial surveys. The area of the Star Lake prospect occurs above the 1,500 foot (460 m) elevation and was not covered by Lake Agas iz. The effectivene of till sampling as a surface sampling medium was tested in those areas above the clay level. Till orientat ion surveys were carried out at the Star Lake property and the Tower Lake prospect (Waddy Lake area) within the La Ronge Domain . Gold grain counts and analy es of heavy mineral concent rate from 7 kg surface ti ll samples were used to delineate dispersion trains down-ice from mineralization. In addition, the clay fraction and a 30 g (-80 mesh) subsample from the same till sample, were analyzed for gold . In the Star Lake area, ice direction is subparallel to the strike of several narrow northeast trending auriferous structures. arrow dispersion trains down-ice from known

Jan 1, 1986

By Rodney R. Koch

The phys ica l properties of gold should faci li tate its detection. However, the average concentration of gold in the ea rth's cru st precl udes the ability of geophys ical methods to detect the metal directly. In order to effectively pursue geophys ical detection and location of gold mineralization there must also be geological input - i.e. a model. This will lead to the selection of the appropriate geophy ical techn ique(s) in the fo llow-up programs. Interpretation of the fie ld survey data is of con iderable importance in expl oration geophys ics. Analytical techniques such as cont inuation, fi ltering, and spectral analys is, are now routinely empl oyed in the analys is of survey data to aid the interpretation process. The uccessful application of geophysical methods and the use processing techniques is demonstrated by two recent Saskatchewan discoveries. The first, the Star Lake 21 Zone, with reserves of 230,000 tons grading bener than 17.14 git Au associated with a disseminated sulphide quartz-bearing shear zone yielded geophysical anomalies that were distinctive, obvious, and would have lead directly to its discovery. The econd , the Laurel Lake Prospect, with ore grade intersections of 28.0I git Au and 52 .46 git Ag· over 5.49 m, resulted in numerous geophysical anomalies. However, none of these anomalies demonstrated association with the mineralization until processed results indicated that structural features crosscuning regional trends were important cont rol mechanisms for the mineral ization.

Jan 1, 1986

By A. H. Ransom, M. E. Robb

The Salmita Gold Mine is located 240 air kilometres northea t of Yellowknife on the east shore of Matthews Lake. Salmita is one of several gold showings which are regionally associated with the steep easterly dipping contact zone between mafic, intermediate and fe lsic volcanics to the west and overlying finely laminated argillaceous sediments to the east. The volcanic assemblage forms a narrow 2 m to 7 m wide north to northwesterly trend ing Belt of Yellowknife Supergroup Archaen greenstone rocks. The contact zone exhibits exhalite character and the increased sulphide content provides a di stinct VLF-EM , IP/Resisti vi ty and/or magnetic signature. Gold occurs at or near this contact in three main settings: associated with si liceous vein-like structures; with finely disseminated sulphides within ericitic altered upper fe lsic tuffaceous unit ; or with quartz in narrow shear zones within the overlying sediment . The B-Vein is of the former type with free mi ll ing gold occurring within a highly sil iceous zone having an average widtn of 1.69 m. Alteration is intense within the immediately su rrounding host lithologies and includes the development of si lica, carbonate, sulphide, sericite and chlorite with minor graphite, epidote. tourmaline and scheelite. The mineable zone above the 4th level (-200 m) ha an average strike of 160 m and is divided into three south plunging ore shoots separated by the regional Salmita Shear Zone in the south and by a low-grade structural hiatus in the north. Production from the B-Vein commenced in August 1983 based on a diluted in situ ore reserve of 140,000 t grading 26.6 git Au . As of December 31, 1985, a total of 131 ,537 t grading 27.8 git Au have been mined at a ra.te of 160 t per day and a 96.4 percent recovery, to produce 3,522 ,000 g (113,227 ounces) of gold . Current (January I, 1986) reserves total 45,500 t grading 37 g/t Au down to the 10th level (-500 m) .

Jan 1, 1986

By Robert Macdonald, William Coombe, John F. Lewry

Gold occurrences have been known in the La Ronge Domain for many year . Mineable reserves have more recently been outlined and there is every prospect of a major gold camp being established in the domain within this decade. The La Ronge Domain lies in the Lower Proterozoic 'Trans-Hudson Orogen' and is part of a collage of Early Proterozoic crust comprising volcanoplutonic arcs, batholiths, associated volcaniclastics and volcanogenic sediments lying between the Superior Craton to the outheast and the reworked Archean basement/Aphebian cover terrain to the northwest. The domain has several lithostructural subdivisions, the most important of whjch , from a gold exploration point of view, is the Central Metavolcanic Belt. This belt is composed dominantly of a range of metavolcanic rocks and gabbroic to granitic intrusives, which geochemically resemble younger subduction-generated 'primitive' arcs developed on oceanic crust. U-Pb zircon geochronology indicates that the arc volcarusm and pre- to late-kjnematic plutonism occurred about 1890 Ma to 1850 Ma ago. The belt has an attained grade of upper greenschist to amphibolite facies and is relatively undeformed , though high strain zones occur locally. Most gold occurrences in the La Ronge Domain have been found in the Star-Waddy Lakes area of the Central Metavolcanic Belt, and in the Sulprude-MacKay Lakes area to the south which is interpreted as a tectonically dismembered part of the main belt. Both tratiformand vein-type gold occurrences are present in the domain; vein-type predominate and form nearly 90 per cent of the occurrences. The stratiform-type occurrences show a regional lithological a sociation with iron-rich sediments within proximal felsic volcanjc sequences. Some vein-type occurrences appear related to brittle fracturing associated with intrusive emplacement (the magmatic-hydrothermal "syn:' and "subvolcanic" veins) and faulting. However, most of the vein-type occurrences exhibit a spatial association with regionalscale ductile shear and other high strain zones, and were probably formed by metamorphichydrothermal processes.

Jan 1, 1986

By P. K. Gummer

Gold was fir t di covered on the Seabee property in 1947 by the Con olidated Mining and Smelting Company Limited. Acquired by Claude Resource Inc. in 1984, the property is now being explored by Placer Development Ltd . in joint venture with Claude Re ources. Between Augu t, 1985 and March, 1986, Placer completed 54 drill holes, extending the main o. 2 and o. 5 vein y tern to a depth of 1000 feet below surface and di covering two new satellitic gold zone 800 feet west of the o. 5 gold zone. Drill proven and probable geological re erve in four zone ( os. 2, 5, II, 14) to a vertical depth of 1000 feet, are approximately 1,120.000 tons averaging 0.32 oz. Au/ton.

Jan 1, 1986

By Ian Hattie, Mark R. Wilson, T. Kurtis Kyser, Brian W. Janser

Petrographic, chemical and isotopic compo itions of auriferous and non-auriferous quartz vei ns from the Sta r Lake and Flin Flin-Amisk Lake areas of northern Saskatchewan indicate diver e origins fo r the fluids associated with gold mineralization. In the Sta r Lake area, the metavolcanic , Star Lake pl uton, and heared mafic dikes have retained their original igneous 81 80 values. The 81 80 value of quartz from mi neralized veins vary by I per mi! and range from+I0 to+IJ. The only quartz ample having a 81 80 value outside th is range came from a vein not associated wi th a dike or gold mineralization . Quartz from the Star Lake pluton has identical 8180 value to the qua rtz from mi neralized vei ns which suggests that the vei ns and the pluton are related to imilar proces es. The diffe rence in 81 80 values between mi neralized and barren vein may erve a a potential exploration tool in this area. Because o34S val ues of a limi ted number of amples of pyrite from gold-bearing quartz vei ns at Star Lake correlate directly with gold content. the gold may have been syngenetic with the su lphur and the 834 value may be useful for exploration . 8180 values of co-existing quartz, calcite, and amphibole in the veins from Star Lake indicate that isotopic disequilibrium among the minerals is common, but the val ues also record a high temperature of formation (ea . 500°C) involvi ng a component of magmatic fl uid. TheoD value of hydrou mineral from Star Lake retain their original igneous values but whole rock values are generally much lower, an effect attributed to interaction of the minerals with a late meteoric water. In the Fl in Flin-Amisk Lake area, auriferou and barren quartz veins formed from a mixture of hydrothermal and metamorph ic flu id at lower temperatures (ea . 350°C) than those at Sta r Lake. Becau e there i no apparent correlation between 8180 values of the quartz with gold content or relative age of the vein , nor between the 834S val ues of pyrite and gold content, table isotopes appear limited as an exploration tool in the Fl in FlonAmisk Lake areas.

Jan 1, 1986

By T. I. . I. Sibbald, D. E. Jiricka

The Goldfields area on the north shore of Lake Athabasca , was active in the thirties and early fortie . In 1934, Tom Box discovered gold mineralization in quartz veins in pyritized 'granite' at the ite of what wa to become the Box Mine of the Consolidated Mining and Smelting Company of Canada Ltd . In the rush of activity that followed numerou other gold occurrences were found. the most significant of the e being the Athona and Frontier prospects which underwent underground development bur did not reach production. Probable reserve identified to date in the Box and Athona deposits amount to some 3.5 million ton grading an average 0.ITT oz gold/ton . Some 10 to 15 million tons of lower grade, po ible reserve are also reported at the Box. From 1939 to 1942, the mine produced, from underground , 64,066 ounces of gold from ore grading 0.0452 oz gold/ton at a cost of between $1.5 and $2.0 a ton. The Goldfield area is underlain by upracrustal rock intruded by mafic bodies and invaded by ·granite'. The upracru tal . thought to be of Lower Proterozoic age are characterized by a helf-type ucce ion metamorpho ed under lowermiddle amphibolire facie conditions into quartzites, quartz-mica chi ts. dolomitic marbles, diop idic calc-silicates and cordierite-anthophyllite-biotite schi t . Amphibolites of presumed igneou origin form concordant to subconcordant units up to a few ten of metre thick in the upracrustals and occur as le regular masses in the 'g ranite·. Compositionally they vary from gabbroic to granodioritic. with the more mafic varieties being most common. Granitic rocks exhibiting a variety of textural , structural and compositional characteristics underlie most of the area. Four main units are recognized: foliated (older) 'granite', 'leucogranite', feldspar augen 'granite· and pyritic mine 'granite', however, in geological mapping the e are somewhat arbitrarily differentiated due to transitional relationships and admixture of types. Although there is no unambiguous age data available for the e 'granite ' adjacent northshore 'granite' of geologically similar age yield Rb-Sr isochron dates around 2000 Ma. The area is characterized by two major deformation events of which the earliest gave rise to the dominant regional foliation and to rare minor and outcrop scale folds. This foliation which in general parallels compositional layering is folded into the major Goldfields syncline, whose axis plunges weakly to moderately outh. Related open minor folds have subvertical axial surfaces which are locally paralleled by a weakly defined schistosity. Most rock display a pronounced rodding fabric, coaxial with second fold axes and apparently the product of this deformation event. However, a note of caution is introduced into this interpretation, as the rodding fabric is also parallel to first fold axe .

Jan 1, 1986

By W. L. Murphy

The Star Lake property, located 115 km northeast of La Ronge, Saskatchewan is underlain by metamorphosed andesitic tuffs and flows which have been intruded by the dioritic to granitic Star Lake Pluton. Gold mineralization on the Star Lake property was first discovered at Ru h Lake by E. Beveridge in 1959 and by M. and E. Hird in 1961. In 1960 E. Partridge discovered Kahn 18 and Kahn 28. In 1982 the SMDC-Starrex joint venture completed geophysical and geochemical urveys including magnetics, VLF, IP/Resistivity, vegetation, bulk till and oil sampling, followed by drill testing of pecific targets. To date the most ignificant depo it is the 21 Zone which contain drill indicated reserves of 230,000 tons grading 0.5 oz/ton Au . The 21 Zone con ists of quartz with 5-10% (locally > 30%) drusy pyrite, minor chalcopyrite and trace amounts of scheelite, chalcocite and arsenopyrite. The 21 Zone is enclosed by a 25-50 m wide band of mylonitized monzonite. The mylonite occurs in the central portion of a 300 m wide northeasterly trending zone of brittle deformation .

Jan 1, 1986

By K. Howard Poulsen

Shear zones are tabular tructures which tend to occur either discordantly within, or concordantly along the margins of, competent rock masse uch as plutons, sill or flows. They contain deformed equivalents of their host rock and are common sites for gold mineralization localized in tructure oriented y tematically relative to the shear zones and internal linear fabric. Apan from genetic implications, hear zone analysis proves useful in exploration for this type of deposit because the zones are generally wider and more continuous than associated mineralization and because there is an element of predictability to mineralization geometry (i.e. vein orientation. plunge).

Jan 1, 1986

By Samuel B. Rombeger

The behavior of gold in hydrothermal systems is evaluated as a function of pH and oxygen and sulphur activities at temperatures to 250°C. Under conditions of stability of pyrite and argillic alteration as emblages, gold will be transported as bisulphide complexes. In systems containing significant amounts of arsenic, thioarsenide complexes may be important. Oxidation, dilution and reduction in sulphur activity would cause gold deposition from saturated solutions under these conditions. Gold chloride complexes will predominate under oxidized conditions where hematite or other oxides are stable and depo ition would result from increase in pH and/or reduction . Absorption and coprecipitation are po sible mechanisms of deposition for gold in certain low grade depo it . Low concentrations of gold in the transporting solution combined with the ignificant solubility of gold as bisulphide complexes, sugge t hydrothermal solutions rarely may be saturated with gold and coprecipitation with sulphides may be an important initial depositional process. Recrystallization of the sulphides in the presence of the hydrothermal solution would be re ponsible for release of gold to more table ite . Thi mechani m i supported by the close association of gold with pyrite in many hydrothermal gold deposits.

Jan 1, 1986

By Lloyd W. Trevoy

Syncrude Canada Limited is presently studying commercial production of heavy minerals from plant tailings of the openpit A lhabasca tar sands operation. When tar sands are processed and upgraded to synthetic crude oil, heavy minerals can be removed f rom the extraction circuit and beneficiated to provide concentrates of zircon and titanium minerals. Calculated recovery rates indicate that crude oil production capabilities of 105,000 barrels per day would provide 26,000 tonnes of zircon and 114,000 tonnes of titanium minerals annually. The titanium minerals concentrate is a mixture of ilmenite, leucoxene and rutile; it could be used as recovered or upgraded to synthetic rutile. With the consrruction of further synthetic crude oil plants in Western Canada, a large reserve of heavy minerals will become available.

Jan 1, 1984

By Z. D. Hora

Numerous asbestos occurrences are known, and the Cassiar Mine in Northern British Columbia has been a major producer since 1952. The Kutcho Creek deposit is a large medium-grade deposit of potential economic interest. OF THE numerous British Columbia asbestos occurrences, only one mine exists. Another property, at Kutcho Creek, may be commercially viable. Cassiar Mine, in the northern part of the province, has been producing high-quality asbestos since 1952 and is described elsewhere in this volume. The Kutcho Creek property is situated north of Letain Lake about 125 km southeast of Cassiar Mine. The Kutcho Creek asbestos deposit comprises zoned chrysotile fibre veins in a well jointed and locally sheared serpentinite sill. The sill intrudes, more or less concordantly, a sequence of Devonian to Mississippian argillaceous Industrial Minerals in Canada metasedimentary, calcareous, and volcanic rocks. The light to dark green serpentinite contains crossfibre chrysotile veins that are usually less than 1 cm in width but up to several metres in length. Typical sections in exploration drillholes grade between 2.5 and 3.0 per cent fibre. According to the last assessment report submitted, test results indicate that the Kutcho Creek property may contain a large, medium-grade asbestos deposit of potential economic interest.

Jan 1, 1984

By PETER O. SANDVIK

The Cargill deposit, located 32 km south west of Kapuskasing, Ontario, was discovered by International Minerals and Chemical Corporation in 1975 and has been evaluated through an extensive program of drilling, chemical analyses, metallurgical tests and engineering and economic studies. The Cargill alkalic complex, comprising mainly carbonatite and pyroxenite-amphibolite rocks, was intruded into the rift system of the Kapuskasing magnetic-gravity high. Weathering and leaching under assumed temperate to cool climatic conditions plus faulting, shearing and/ or initial petrographic variations within the carbonatite developed a small, locally confined karst system. This resulted in a thick enriched leached carbonatite zone capped by troughs and sinks, and filled with a residuum of apatite, goethite, clay and other minerals. Residuum thickness ranges from nonexistent on ridges to 170 m in troughs and sinks. Apatite values are 5 to 15% in fresh carbonatite, 20 to 40% in leached carbonatite and 20 to 98% in residuum. A tentative open-pit mine designed for preliminary feasibility studies is estimated to contain 62.5 million tonnes averaging 19.6% P20 5.

Jan 1, 1984

By Kilmar Mine

The Kilmar dolomitic magnesite deposit~ in sourhwesr Quebec lie in Grenville Province sedimentary rocks that strike north and dip steeply west. The sediments comprise quartzitic, carbonate and argillaceous members. The middle or carbonate member hosts the magnesite and, like the two other members, has been intensely mewmorphosed. Magnesite occurs as lenticular shaped zones of altered limestone and is mixed with 5 to 30% dolomite crystals. Diopside, serpentine and mica are common accessory minerals. Magnesite appears to have formed from merasomarism of all or part of the carbonate member due to intrusion of hot magnesia-rich solutions. Magnesite is mined from a 490 m vertical shaf1 and is milled and burned into clinkers, which then are shipped 10 pyroprocessing industries around the world.

Jan 1, 1984