jacobsite
noun
ja·cobs·ite
ˈjākəbˌzīt sometimes -kəpˌsīt
plural -s
: a black magnetic isometric mineral MnFe2O4 consisting of an oxide of manganese and iron and constituting a member of the magnetite series
Word History
Etymology
French jakobsite, from Jakobsberg, Sweden, its locality + French -ite