Calcite

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”.

Calcite derived from the German Calcit, a term coined in the 19th century from the Latin word for lime. Calx (genitive calcis) with the suffix -ite used to name minerals. It is thus etymologically related to chalk.

It has a specific gravity of 2.71, and its luster is vitreous in crystallized varieties. Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, or even black can occur when the mineral charged with impurities.