What is "fletcherite"

n. (context mineral English) An isometric-hexoctahedral steel gray mineral containing cobalt, copper, nickel, and sulfur.

Fletcherite is a rare thiospinel sulfide mineral with formula Cu(Ni,Co)S. It is an opaque metallic steel gray mineral which crystallizes in the cubic crystal system. It is a member of the linnaeite group.

It was first described in 1977 for an occurrence in the Fletcher Mine, Viburnum Trend (New Lead Belt), near Centerville, Reynolds County, Missouri.

It occurs as a dissemination within copper sulfide minerals in mineralization replacing dolostone at the type locality in the Fletcher mine where it is associated with vaesite, pyrite, covellite, chalcopyrite, bornite and digenite. In an occurrence in Kalgoorlie, Australia it is found in black slate associated with pyrrhotite.