Richard D. Hagni

Reflected Light Microscopy of Industrial Minerals

The use of reflected light microscopy to study industrial minerals has been largely overlooked and neglected. Industrial minerals are much darker than ore minerals, and this property has tended to dissuade most microscopists from studying industrial minerals in polished sections under reflected light. Furthermore, the reflectance (R) values for most industrial minerals are not listed in standard reference works. The most useful property of industrial minerals for their identification under reflected light is their reflectance (R). The reflectance of most industrial minerals ranges from 3 to about 9. This range is similar to Portland cement clinker phases and brighter than coal macerals. This communication provides reflectance values for some of the common industrial minerals, and provides some examples of the character of industrial minerals as viewed under reflected light.

Ore Microscopic Study of Copper Losses from Mining of Bornite Ores in the Sweetwater Mine, Viburnum Trend, Southeast Missouri

The bornite pods in the Viburnum Trend of the southeast Missouri Pb–Zn district are unique in their mineralogy and textures with respect to typical Mississippi Valley-type ores in that district and elsewhere. The pods are small bodies of massive sulfide ores with very fine grains requiring ore microscopic study. A recently mined bornite pod at the Sweetwater mine was found to consist of 90-vol% spheroidal bornite, 5–10-vol% anhedral chalcopyrite, and 1–12-vol% early carrollite crystals partly replaced by subsequent chalcopyrite and bornite. Small amounts of gersdorffite, tennantite, and pyrite also are locally present.Beneficiation of the Sweetwater bornite ores resulted in low copper recoveries. This study was undertaken to examine the copper mineralogy and to determine their effect on the beneficiation results. Minerals with low copper content had insignificant influence upon the concentrate grade. The diminished copper recoveries were due to bornite losses to the tailings.

Mineralogy and petrology of the lead-zinc-copper sulphide ores of the Viburnum Trend, southeast Missouri, U.S.A., with special emphasis on the mineralogy and extraction problems connected with cobalt and nickel

The ore deposits of the Viburnum Trend in the Southeast Missouri Lead District form the world’s largest lead producing district. The district is comprised of eleven mines, ten of which are currently in production. The principal minerals are few in number, simple in composition, and form simple superposition and replacement textures. The economically valuable minerals are the sulphides, galena, sphalerite, and chalcopyrite; silver is recovered from galena and cadmium from sphalerite at the lead smelter and zinc refinery. The most abundant gangue minerals are dolomite, pyrite, marcasite, calcite, and quartz. The Viburnum ores, however, contain a diverse assemblage of minerals uncommon in most Mississippi Valley-type ore deposits. These include: siegenite, bravoite, vaesite, fletcherite, nickelean Carrollite, bornite, gersdorffite, tennantite, enargite, luzonite, millerite, polydymite, chalcocite, digenite, anilite, djurleite, covellite, blaubleibender covellite, pyrrhotite, magnetite, anhydrite, and dickite.