mineral

Calcite

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: White to colorless (transparent/translucent); Luster: Vitreous to pearly; Crystal structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral in three directions; Specific gravity: 2.71

Hardness: 3 on Mohs scale
Color: White to colorless (transparent/translucent)
Luster: Vitreous to pearly

Identified April 28, 2026More mineral →

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Physical properties

Formation & geological history

Primarily forms through chemical precipitation in marine environments or as a secondary mineral in igneous and metamorphic rocks. It is basic to the formation of limestone and marble.

Uses & applications

Used widely in the construction industry as an ingredient in cement and mortar, in agriculture for soil treatment, as a pigment, and occasionally as a gemstone or ornamental stone.

Geological facts

Calcite exhibits double refraction; if you look through a transparent crystal, objects behind it appear doubled. It is also the primary component of stalactites and stalagmites in caves.

Field identification & locations

Identify in the field by its rhombohedral cleavage and its strong reaction (effervescence) to dilute hydrochloric acid. It is found globally in sedimentary basins and limestone quarries.