Chromite

Formula:  FeCr₂O₄

Origin of name:  From composition

Crystal system:  Cubic

Crystal class:  4/m -3 2/m

Twinning:

Unit cell:

Colour:  Black

Diaphaneity:  Opaque

Luster:  Metallic

Habit: Crystals octahedral; massive, compact to fine granular

Hardness:  5.5

Specific gravity:  4.5 to 4.8

Cleavage:  None

Tenacity:

Streak:  Brown

Synonyms/varieties:

Comments:  Series with magnesiochromite and with hercynite