Composition: Calcium carbonate
Nomenclature: Named after the Greek word chalx which means "burnt lime" because of its chemical composition.
Industrial Uses: Cement, optical polarizers, optical bombsights.
Additional Notes: A very common mineral with many varieties. The variety Iceland spar exhibits the property of double refraction; that is, an image viewed through a rhomb of Iceland spar will appear doubled. This occurs because calcite separates a beam of light into two perpendicularly-polarized beams which are refracted (bent) by significantly different amounts. Iceland spar was used during World War II to manufacture optical bombsights, since the calcite rhomb has the ability to counteract the effects of parallax. Massive calcite is referred to as travertine.
Azerbaijan : Scott 420 : 10 manat : 15 Jun 1994
Calcite on epidote
Bulgaria : Scott 3898 : 5 leva : 20 Nov 1995
Chile : Scott 1179c : 150 pesos : 9 Aug 1996
Comoro Islands : Scott 933 : 1125 francs : 1998
Calcite; Rutile in Quartz; Wulfenite
France : Scott 2019 : 4 francs : 13 Sep 1986
Kyrgyzstan : Scott 42 : 90 tyiyn : 1 Dec 1994