Calcite

Photo Copyright © Rob Lavinsky & irocks.com

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

Locality: Cairns Bay, Flinders area, Victoria, Australia. Photo Copyright © Steve Sorrell
Locality: Zinc Corporation Mine, Southern operations mine, Broken Hill, Yancowinna Co., New South Wales, Australia. Photo Copyright © Keith F Compton
Locality: La Sambre Quarry, Landelies, Montigny-le-Tilleul, Hainaut Province, Belgium. Photo Copyright © Harjo Neutkens
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