Oosterboschite , Trogtalite , Cuprosklodowskite , Quartz Locality: Musonoi Mine, Kolwezi, Kolwezi District, Katanga Copper Crescent, Katanga (Shaba), Democratic Republic of Congo (Zaïre) Size: 4.2 x 2.9 x 2.3 cm Oosterboschite and trogtalite are very rare selenides, with the former having palladium and copper and the latter having cobalt. The famed Musonoi is the Type Locality for Oosterboschite. This piece is from the Howard Belsky Collection, who collected many rare species. We believe the splendent gray crystals on one end surrounded by a green mineral are the oosterboschite. The quartz matrix holds several vugs richly lined with gemmy, green cuprosklowdoskite needles. The brown crystals richly lining one vug could be oxidized trogtalite, as MINDAT lists this species as being rose-violet. X-ray work would be needed to confirm species identifications in a normal case but, as this is from the Belsky Collection, it’s pretty certain to be legitimate. He had his own analytical setup and did much work with friends in museums, specializing in rarities. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Trogtalite
A rare rose-violet cobalt diselenide of the pyrite group.
Intro adapted from Wikipedia (CC BY-SA).
Trogtalite is an IMA-recognized mineral species in the sulfide class, with the chemical formula CoSe₂.
It crystallizes in the cubic crystal system (space group Pa3). It is a member of the Pyrite structural group.
Key properties: Mohs hardness 7; specific gravity 7.09; Metallic. R: (400) 42.5, (420) 42.2, (440) 41.9, (460) 41.4, (480) 41.0, (500) 40.8, (520) 41.1, (540) 41.3 luster.
IMA symbol Trg, grandfathered status — known before the IMA’s founding, named in 1955.
Intergrown with clausthalite (Trogtal quarry, Germany).
It is found associated with Clausthalite, hastite, bornhardtite, selenium, gold (Trogtal quarry, Germany); oosterboschite (Musonoi mine, Congo).
The name refers to the occurrence at the Trogtal quarry, Germany.