jacobsite

manganese iron oxide mineral, a member of the magnetite (q.v.) series of spinels.[1 related articles]
Found on http://www.britannica.com/eb/a-z/j/3

Jacobsite

Spinel structural group | boxwidth = | image = Jakobsit - Jakobsberg, Schweden.jpg | caption = | formula = iron(II,III) manganese oxide, MnFe2O4 | strunz = 04.BB.05 | symmetry = Isometric (4/m 3 2/m) | unit cell = a = 8.457 Å; Z = 8 | molweight = | color = Black to brownish black | habit = Disseminated to massive, rarely as octahedral crystals | ...
Found on http://en.wikipedia.org/wiki/Jacobsite
No exact match found