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 July 17, 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, primarily from the shells of marine organisms or as a chemical precipitate in caves or hot springs. Blue coloring is often caused by micro-inclusions of other minerals or structural defects.

Uses & applications

Used primarily for ornamental purposes, lapidary carvings, tumbled stones, and as a popular specimen for mineral collectors. Also used as a metaphysical stone.

Geological facts

Calcite is one of the most common minerals on Earth, but the blue variety is highly prized for its soft, calming aesthetic. It will react and effervesce (fizz) if exposed to weak acids like vinegar.

Field identification & locations

Identify by its 'soapy' or waxy feel, distinct rhombohedral cleavage planes, and soft blue color. It can be scratched by a copper penny but not by a fingernail. Found extensively in Mexico, Madagascar, and Brazil.