Minerals Topics

Major Mineral Groups (Part 10)


• Carbonate minerals contain carbonate (CO3), a combination of carbon and oxygen, combined with other elements.

• Common carbonate minerals include: calcite and dolomite.

Calcite Pronounce:

• Calcite has a composition of CaCO3.

• Calcite is identified by its glassy to earthy luster; color variety; and its perfect cleavage in three directions (not at 90 degrees).  Calcite fizzes in hydrochloric acid.

• Its hardness is 3.

• Its specific gravity is 2.7.

• Calcite forms the rocks limestone and marble.  It is used in fertilizer, cement, paper, building stone, and many other industries.

CalciteCalcite has excellent cleavage in three directions at 75 degrees, and commonly forms the rhombohedral shapes seen here.  Another property of calcite is double refraction, meaning light traveling through the mineral forms double images. (Photograph by Parvinder Sethi)


Calcite rosette
Calcite is the most common carbonate mineral.  It is very abundant in the sedimentary rock limestone.  Limestones form in clear, shallow tropical seas. (Photograph by Parvinder Sethi)