Calcite

Very common mineral of the "carbonates and nitrates" class

Shop for Calcite

Facetted calcite from Dalnegorsk, Primorje, Russia

^{Due to very low Mohs hardness 3 as well as perfect cleavage calcite poses a real challenge for gem cutters. Thus facetted specimens are extremely rare.}

Origin of name: from Greek χάλιξ [chálix] for lime. In Latin it became calx, calcis describing lime used for the production of mortar.
In 1845 it was named calcite by Austrian mineralogist and geologist Wilhelm Karl Ritter von Haidinger.

Synonyms and trade names: calciumcarbonate, kalkspat, doublespat, icelandspat etc., calzite,

Can be confused with: the chemically identical but rhombic aragonite as well as with a plethora of similarly coloured minerals. Identification via refractive index, birefringence and, if permissible, reaction to acids is usually no big deal, though.

Localities: very common worldwide and mined extensively for use in many industries (construction, iron and steel, paper, agriculture, forestry and more).

3 calcites from Sonora, Mexico

Handling: due to low hardness, perfect cleavage and extreme reactivity with all kinds of acid, calcite is hardle usable as a gemstone.

Worth knowing: calcite is the most common natural calcium carbonate, occurring in numerous modifications and varieties. These are named after crystal habitus (cannonspat, paperspat, dogs-tooth-spat, poker chip calcite etc.), colour (honey calcite, orange calcite, hematoconite, a blood-red calcite coloured by inclusions of hematite) or impurities (manganese calcite, iron calcite, lead calcite etc.)

Manganese calcite from Romania

Stinkcalcite is a particular oddity. It contains hydrogen sulphide in cavities which, when opened during cutting, emit a strong odour of rotten eggs.

Shop for Calcite