stilpnomelane
noun
stilp·no·mel·ane
ˌstilpnōˈmeˌlān
plural -s
: a black or greenish black mineral K(Fe,Al)10Si12O30(O,OH)12 (?) occurring in foliated plates, fibrous forms, and velvety bronze-colored incrustations and consisting of a hydrous iron aluminum silicate with a little potassium (specific gravity 2.77–2.96)
Word History
Etymology
German stilpnomelan, from Greek stilpnos glistening + melan-, melas black