Calcite
| Colour | Clear, White, Orange, Brown |
|---|---|
| Mohs hardness | 3 (defining mineral) |
| Lustre | Vitreous to pearly on cleavage surfaces |
| Streak | White |
| Crystal system | Trigonal |
| Transparency | Transparent to translucent |
| Cleavage | Perfect on {101} three directions with angle of 74° 55' |
| Fracture | Conchoidal |
| Chemical formula | CaCO 3 |
| Specific gravity | 2.71 |
What is Calcite?
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses.
How to identify Calcite
- Lustre: Vitreous to pearly on cleavage surfaces.
- Hardness: Mohs 3 (defining mineral) — soft; a knife will scratch it.
- Streak: White.
- Habit: Trigonal crystal system.
Calcite in different forms
Stones often confused with Calcite
Frequently asked questions
How hard is Calcite?
Calcite is Mohs 3 (defining mineral) on the hardness scale.
What colour is Calcite?
Calcite is typically clear, white, orange, brown (Typically colorless or creamy white - may have shades of brownish colors).