mineral

Blue Calcite

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: Pale blue to sky blue, often with white or grey banding; Luster: Vitreous to pearly/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, often with white or grey banding
Luster: Vitreous to pearly/waxy

Identified March 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed through sedimentary processes or as a secondary mineral in igneous and metamorphic rocks via precipitation from calcium-rich hydrothermal fluids. Most commercial blue calcite is sourced from Precambrian or Paleozoic limestone deposits.

Uses & applications

Primarily used for decorative carvings, polished spheres, and metaphysical collecting. Also used in industry as an ingredient in cement, as an acid neutralizer, and as a soil conditioner.

Geological facts

Blue calcite is known for its 'soapy' or waxy feel when polished. It is extremely soft, meaning it can be scratched by a copper penny. Like all calcites, it will effervesce (fizz) when in contact with weak acids like vinegar.

Field identification & locations

Identify in the field by its distinct rhombohedral cleavage, softness (3 on Mohs scale), and pale blue color. It is most commonly found in large deposits in Madagascar and Mexico. Collectors should look for deep blue saturation and minimal internal fractures.