Wiktionary
fingerite
n. (context mineral English) A triclinic-pinacoidal black mineral containing copper, oxygen, and vanadium.
Wikipedia
Fingerite
Fingerite is a copper vanadate mineral with formula: β-CuVO. It was discovered as triclinic crystals occurring as volcanic sublimates around fumaroles in the crater of the Izalco Volcano, El Salvador.
Associated minerals include thenardite, euchlorine, stoiberite, shcherbinaite, ziesite, bannermanite, chalcocyanite and chalcanthite.
Fingerite is named for Larry W. Finger (b. 1940) of the Carnegie Institution.