mineral

Blue Calcite

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: Pale blue to sky blue; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral in three directions; Specific Gravity: 2.71

Hardness: 3 on Mohs scale
Color: Pale blue to sky blue
Luster: Vitreous to waxy

Identified March 15, 2026More mineral →

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Physical properties

Hardness: 3 on Mohs scale; Color: Pale blue to sky blue; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral in three directions; Specific Gravity: 2.71

Formation & geological history

Formed through sedimentary processes or as a secondary mineral in igneous and metamorphic rocks. It often precipitates from hydrothermal solutions or forms in marine environments where calcium carbonate accumulates. Large deposits are often found in Madagascar and Mexico.

Uses & applications

Primary use is in the gemstone and metaphysical industry as decorative carvings, palm stones, and jewelry. Industrial calcite is used in the manufacture of cement, lime, and as a filler in plastics and paints.

Geological facts

Calcite is one of the most common minerals on Earth, but the blue variety is specialized. It is known for its 'double refraction' property, where light entering the crystal is split into two rays, though this is harder to see in opaque blue specimens than in clear ones.

Field identification & locations

Identify by its 'soapy' or waxy feel and its reaction to cold dilute hydrochloric acid (it will fizz/effervesce). It is much softer than quartz or fluorite. Commonly found in limestone quarries or specialized mineral deposits in Madagascar.