noun
or ka·top·trite kəˈtäpˌtrīt, ˈkad.əpˌ-
( -s )
Etymology: Swedish katoptrit, from Greek katoptron + Swedish -it -ite; from its mirrorlike cleavage surfaces
: a mineral consisting of a silico-antimonate of manganese, aluminum, magnesium, and iron occurring in metallic black monoclinic crystals