catoptrite
noun
ca·top·trite
variants or katoptrite
kəˈtäpˌtrīt,
ˈkatəpˌ-
plural -s
: a mineral consisting of a silico-antimonate of manganese, aluminum, magnesium, and iron occurring in metallic black monoclinic crystals
Word History
Etymology
Swedish katoptrit, from Greek katoptron + Swedish -it -ite; from its mirrorlike cleavage surfaces