Chromite

Chromite, an oxide mineral, is the major ore of chromium. It is often used for the bricks and linings of blast furnaces as it can withstand very high temperatures.

Chromite is one of the first minerals to crystallise in deep ultra- mafic magmas, and becomes concentrated as it sinks to the bottom of the magma chamber.

Chemical composition - FeCr 2O 4
Hardness - 5.5
Specific gravity - 5
Transparency - Opaque
Colour - Brownish black to black
Streak - Brown
Lustre - Metallic to semi-metallic
Cleavage/fracture - Non-existent / uneven, hackly
Crystal habit/mode of occurrence - Prismatic (octahedron) / massive, granular