mineral

Calcite in Matrix

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: White to colorless; Luster: Vitreous to pearly; Crystal structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral in three directions; Specific Gravity: 2.71

Hardness: 3 on Mohs scale
Color: White to colorless
Luster: Vitreous to pearly

Identified May 30, 2026More mineral →

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Physical properties

Hardness: 3 on Mohs scale; Color: White to colorless; Luster: Vitreous to pearly; Crystal structure: Trigonal/Rhombohedral; Cleavage: Perfect rhombohedral in three directions; Specific Gravity: 2.71

Formation & geological history

Formed primarily through sedimentary processes by chemical precipitation from calcium-rich solutions or as a biogenic mineral from marine organisms. It can also occur in metamorphic environments like marble or hydrothermal veins.

Uses & applications

Used extensively in the manufacture of cement and mortar, in the chemical industry, as a soil conditioner in agriculture, and as a decorative stone or collector specimen.

Geological facts

Calcite is one of the most common minerals on Earth and is the primary constituent of limestone and marble. It exhibits double refraction (birefringence), where light passing through a clear crystal splits into two rays.

Field identification & locations

Identified in the field by its softness (can be scratched by a copper coin) and its vigorous effervescence (fizzing) when in contact with dilute hydrochloric acid. It frequently forms distinct rhombohedral crystals.