Calcite semiprecious gemstone index and mineral information

Calcite is the most common form of calcium carbonate. It is known for its great variety and the beautiful development of its crystals. Calcite is also called limespar. The name is derived from the Latin word calx, meaning “lime.” More than 300 forms of calcite crystals are known, and they combine into a thousand different variations. Because of its softness it is only faceted for collectors. Calcite is transparent to opaque and may occasionally show phosphorescence or fluorescence. Most calcite is massive, occurring either as limestone or marble. It is also found as fibers, nodules, stalactites and as an earthy aggregate.

Calcite is transparent but gives a double image of things when you look through it.  Usually it is colorless to white.  It can also have a combination of colors, due to impurities, like blue and black. Pink or red calcite, usually named cobaltocalcite is made into beautiful items. The white, fibrous variety of calcite is cut into cabochons for jewelry to show the cat’s-eye effect. Another variety is the Iceland spar, which is found in lava cavities in Iceland, it is colorless and transparent.

It is usually found worldwide in limestone rocks, but especially in Austria, Germany, France, United Kingdom, Iceland, Ireland, Mexico, United States (in New York State, Ohio, Michigan, Illinois, Missouri, North Dakota, Montana, Franklin, New Jersey and Cochise County, Arizona).  In Canada major calcite deposits include Cobalt, Timiskaming County, Ontario.

Mohs’ hardness: 3