metallic metals - Government of Manitoba

The essential nickel-bearing ore-minerals inManitoba are pentlandite and pyrrhotite (fig. 17)which often occur in intimate intergrowths. Theseprimary sulphides may be accompanied by substantialamounts of pyrite or chalcopyrite (fig. 18),giving rise in the latter case to the nickel-copperores. The nickel minerals gersdorffite and violariteare commonly present in minor amounts.Pyrrhotite has been described under the copperzincheading, but it is mainly in the nickel ore-suitesthat it becomes economically important owing toits intimate association with pentlandite. Pyrrhotite(plates 29, 30) may contain up to one per centpentlandite, in usually microscopic intergrowths,and is thus significant as a possible indicator ofnickel mineralization.Pentlandite occurs in massive or granularaggregates intergrown with pyrrhotite, usually on amicroscopic scale (plate 31). It is yellowish bronzewith a pale bronze streak, and closely resemblespyrrhotite in appearance, but can be oftendistinguished by its octahedral parting and lack ofmagnetism. The other nickel minerals to be notedare either or secondary origin or are quantitativelyminor.Smythite, originating as a low-temperature oxidationproduct of pyrrhotite, is a major ore-minerai atManibridge. It is a secondary iron-nickel sulphide,seen as a black replacement around the edges ofpyrrhotite aggregates, and extending irregularlyinwards.Violarite is a relatively common nickel-iron sulphidethat tarnishesrapidly from grey to adistinctive violet-grey or copper-red.Mackinawite is a rare iron-nickel sulphide, occurringat the Pipe Mine as a minor alterationproduct of pentlandite; it is pale grey when fresh,but tarnishes rapidly bronze; the streak is black.Gersdorffite (plate 32) is a hard, silvery whitesulfarsenide of nickel, often resembling pyrite inthe shape of its pyritohedral crystals.Nickeline (niccolite) is a pale copper-red arsenideof nickel (plate 33); it may be coated with greennickel bloom, a secondary oxidation product ofsome nickel minerals.Maucherite is a less well known nickel arsenide,silvery grey but tarnishing copper-red; it may occuras a secondary mineral with nickeline.LYNN LAKE AREAThe first company to produce nickel ore inManitoba was Sherritt Gordon Mines Limited whenthey moved all portable plant, machinery andbuildings from Sherridon to Lynn Lake in the earlynineteen fifties. This major re-Iocation was done bywinter tractor-train before the railway reachedLynn Lake in 1953, leading to the opening up ofManitoba's northernmost mining district. Prospectorsfrom Sherridon had begun reconnaissance ofthe Lynn Lake region in the early nineteen thirties,and in 1941 Austin McVeigh found a mineralizedoutcrop that is now preserved as the "discoveryoutcrop" of the Lynn Lake Mine. It is overshadowedby the headframe of the "A" shaft (L 3) andshows gabbro and amphibolite with gossan derivedfrom oxidation of sulphide stringers and disseminations.The "A" orebody was subsequentlylocated by magnetometer survey and confirmed bydiamond drilling. Nickel-copper ore was produced30