Origin and occurrence of uranium in northern Michigan

Greenockite and Associated Uranium-Vanadium, Minerals from the Huron River Uranium Prospect Baraga County, Michigan

“…Bornite, Cu 5 FeS 4 , is reported as a minor "primary" sulfide phase by Vickers (1956a), but no description is given.…”

“…Chalcocite, Cu 2 S, is reported by Vickers (1956a), but no mineralogical description is given for the species. Some of the greenockite crystals viewed at SEM magnification have patchy coatings of a copper sulfide that may be chalcocite, but we have not confirmed their identification due to paucity of material.…”

“…Covellite, CuS, is reported from the Huron River uranium prospect by Vickers (1956a) and has been noted as small (1mm), subhedral to euhedral, hexagonal crystals, brilliant purple-blue in color, that were recovered from methylene iodide sinks prepared from acid-digested rock.…”

“…Sphalerite, ZnS, is reported as a minor "primary" sulfide phase by Vickers (1956a). It occurs as small, gemmy, pale green cleavages and as dark steel-gray botryoidal masses.…”

“…It may well be that those reports were based on a much larger sampling, including drill cores, that we have not inspected. Vickers (1956a) describes pitchblende as occurring primarily in microscopic grains, "commonly 0.01 mm in diameter." Thus, the presence of such grains could easily be overlooked if not petrographically sought in polished or thin sections, which we did not do.…”