Chemical Formula: CaCO3
Locality: Common world wide.
Name Origin: From the Latin, calx, meaning lime.
System: Trigonal

Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 3 as “calcite”.

Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite at 380–470 °C, and vaterite is even less stable.

Physical Properties of Calcite

Cleavage: {1011} Perfect, {1011} Perfect, {1011} Perfect
Color: Colorless, White, Pink, Yellow, Brown.
Density: 2.71
Diaphaneity: Transparent to translucent to opaque
Fracture: Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments.
Hardness: 3 – Calcite
Luminescence: Fluorescent and phosphorescent, Short UV=yellow, blue, red green, Long UV=yellow, blue, red green.
Luster: Vitreous (Glassy)
Streak: white