Mineral class	Carbonates : Calcite group.
Chemical formula	CaCO3
Crystal system	Trigonal.
Habitus	Calcite is the mineral that shows the most types of crystals (600). Most common forms are tabular, sharp and stubby rhomboedric, prismatic an scalenoedric (dogtooth spar). Calcite also occur as fibric aggregates and coarse to fine grained aggregates or stalactitic.
Cleavage	Perfect rhomboedric in three planes, subconchoidal fracture.
Hardness	3
Density	2.7
Color	usually colorless, but nuances in blue, yellow, green, red, violet, even black and opaque.
Streak	White to grayish.
Luster	Vitreous to pearly or dull.
Occurance	Calcite is the main ingredient of limestone and is found in stalagmites and stalagtites in caves. Calcite is common in hytdrothermal veins and can also occur in eruptive rocks (at depth, it isn't stable at athmospheric pressure - as a melt).
Notes	Reacts violently with hydrochloric acid. Double refractive. Clear calcite is called Iceland spar. Often flourescent when contaminated by manganeese.
Uses	The limestone form of calcite has been extensively used since ancient times. It is burned to quicklime (CaO), slaked to hydrated lime [Ca(OH)2] and mixed with sand to make mortar. Limestone is one of the primary ingredients in the manufacture of portland cement. It is employed in metallurgical processes and as aggregate for both concrete and asphalt mixes. Marble has long been used for statuary and carvings, and as polished slabs for facing stone. Travertine is also a favorite interior facing stone, usually for interior use. Iceland Spar, a transparent form, has been used for optical and crystallography research for two centuries.
Locations	Crystals of calcite is also common, for example at Storstrecks mine, Hofors, Gästrikland. Åstorps makadambrott, Hälsingborg. Grängesbergs mine. Gräsbergs mine, Ludvika. Hesselkulla mine, Närke. Bölets mine, Karlsborg. At Visby and Hoburgen, Gotland. Rönnarp, Skåne. Dylta, Närke. Smålands Taberg. Limestone mines at the Siljansringen. At the manganese mines in Värmland . Drömgruvans quarts quarry, Kolmorden.