Chromite
| Colour | Black, Brown |
|---|---|
| Mohs hardness | 5.5 |
| Lustre | Resinous, Greasy, Metallic, Sub-Metallic, Dull |
| Streak | Brown |
| Crystal system | Isometric |
| Transparency | Translucent to opaque |
| Cleavage | None, parting may develop along {III} |
| Fracture | Uneven |
| Chemical formula | (Fe, Mg)Cr 2 O 4 |
| Specific gravity | 4.5–4.8 |
What is Chromite?
Chromite is a crystalline mineral composed primarily of iron(II) oxide and chromium(III) oxide compounds. It can be represented by the chemical formula of FeCr2O4. It is an oxide mineral belonging to the spinel group. The element magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite (MgCr2O4). Substitution of the element aluminium can also occur, leading to hercynite (FeAl2O4). Chromite today is mined particularly to make stainless steel through the production of ferrochrome (FeCr), which is an iron-chromium alloy.
How to identify Chromite
- Lustre: Resinous, Greasy, Metallic, Sub-Metallic, Dull.
- Hardness: Mohs 5.5 — about as hard as a steel knife.
- Streak: Brown.
- Habit: Isometric crystal system.
Chromite in different forms
Stones often confused with Chromite
Frequently asked questions
How hard is Chromite?
Chromite is Mohs 5.5 on the hardness scale.
What colour is Chromite?
Chromite is typically black, brown (Black to brownish black; brown to brownish black on thin edges in transmitted light).