mineral

Blue Calcite

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale (relatively soft); Color: Sky blue to pale blue, sometimes with white banding; Luster: Vitreous to waxy/pearly; Crystal structure: Trigonal/Hexagonal; Cleavage: Perfect rhombohedral; Specific Gravity: 2.71

Hardness: 3 on Mohs scale (relatively soft)
Color: Sky blue to pale blue, sometimes with white banding
Luster: Vitreous to waxy/pearly

Identified March 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed through sedimentary processes or as a secondary mineral in igneous rocks via crystallization from calcium-rich hydrothermal fluids. It is found in large, massive deposits within limestone and marble beds or as hydrothermal vein fillings.

Uses & applications

Primarily used in jewelry (as beads or cabochons), metaphysical products, and as an ornamental stone. Commercially, it is also used in the production of lime, cement, and as a calcium supplement.

Geological facts

Calcite is unique because of its high birefringence (double refraction), though this is harder to see in the opaque blue variety. Blue Calcite is specifically known for its delicate color, which is often attributed to inclusions of various metal ions during formation.

Field identification & locations

Identify by its 'soapy' or waxy feel and sky-blue color. In the field, it will react (fizz) when exposed to a drop of dilute hydrochloric acid. Commonly found in Mexico, South Africa, and Madagascar. Collectors should look for specimens without large cleavage cracks.