Mindamar Mine

"THE Mindamar zinc-lead-copper mine, owned by Mindamar Metals Corporation Limited, is at Stirling in Richmond County, near the south-eastern shore of Cape Breton Island, Nova Scotia (Figure I). It is connected by several roads with the Canadian National railway at Sydney and St. Peters.The deposit is said to have been discovered around 1895 as an outcrop in the bed of Copper brook, but the details are obscure. Not until 1925, when it was optioned by American Cyanamid Company, was it developed underground. Between 1927 and 1938, the 1-nine was operated intermittently by The British Metal Corporation (Canada) Limited, and yielded approximately 200,000 tons of ore averaging about IO per cent zinc, 2 per cent lead, I per cent copper, and small quantities of silver and gold. In December 1950, Dome Exploration (Canada) Limited made an agreement with Mindamar Metaî Corporation Limited, which was exploring the old mine, to assume management and prepare the property for production. Production started in April 1952 with a new mill and a new four-compartment shaft, and between that time and the end of 1954 it has totalled 545,347 tons of ore averaging 5·89 per cent zinc, 1·35 per cent lead, 0·66 per cent copper, 0·032 oz. gold, and 2 151 oz. silver.The Mindamar orebodies are irregular lenses and large veins lying within a wide, almost vertical shear zone of remarkable persistency. The shear zone consists mainly of well-foliated sericite schist derived from siliceous siltstone, and it contains a vast amount of dolomite and magne-site of hydrothermal origin. Most of the ore is extremely fine-grained and some of the high-grade material has a conspicuous thinly layered structure. The metallic minerals, in order of decreasing abundance, are pyrite, sphalerite, chalcopyrite, galena, and tennantite; the gangue minerals, in the same order, are dolomite and magnesite, quartz, sericite, talc, chlorite, barite, albite, and alunite.The geological setting of the deposit is shown in Figure 2. Except along streams and lake shores, almost all of the bedrock is concealed by glacial drift. The group of rocks in which the deposit occurs consists principally of greywacke, siltstone, tuff, brecoia, and Javas, and has been correlated lithologically with the Bourinot group of Middle Cambrian age. A short distance west of the mine, these rocks are in contact along the Stirling fault with conglomerate, arkosic sandstone, and quartzite belonging to the Middle River group of Silurian or Devonian (?) age, which elsewhere in the area overlies the Bourinot group unconformably. The large bodies of granitic rocks in the region, and the large lenticular masses of diorite and quartz diorite associated with them, have been assigned by Weeks (5, pp. 68-69) to the Devonian."