mineral

Blue Calcite

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: Pale sky blue to light blue-grey; Luster: Vitreous to waxy; Crystal structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral; Specific Gravity: 2.71

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

Identified July 15, 2026More mineral →

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Physical properties

Hardness: 3 on Mohs scale; Color: Pale sky blue to light blue-grey; Luster: Vitreous to waxy; Crystal structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral; Specific Gravity: 2.71

Formation & geological history

Formed through sedimentary processes or as a secondary mineral in igneous and metamorphic rocks via hydrothermal activity. Blue varieties often contain impurities that create the distinct color.

Uses & applications

Primarily used as a decorative stone, in lapidary work for cabochons and carvings, and as a popular metaphysical or collector's specimen.

Geological facts

Blue calcite is known for its 'soapy' or waxy feel when polished. It is extremely soft, meaning it can be easily scratched by a copper penny or a steel knife.

Field identification & locations

Identify in the field by its rhombohedral cleavage, its softness (reacts to dilute HCl), and its distinct waxy luster. Commonly found in large masses rather than distinct crystals in locations like Mexico, Madagascar, and Brazil.