mineral

Calcite

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: typically white, yellow, or 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: typically white, yellow, or colorless
Luster: Vitreous to pearly

Identified June 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed through chemical precipitation from calcium-rich solutions or biological activity (shells). It is a primary mineral in sedimentary environments like limestone caves and hydrothermal veins.

Uses & applications

Used in the manufacturing of cement and mortar, as an agricultural soil neutralizer, in the optical industry (Iceland Spar), and sometimes as decorative carving stone or minor lapidary material.

Geological facts

Calcite is famous for its double refraction property; when light passes through a clear specimen, it splits into two rays, making objects behind it appear doubled. It is the primary component of stalactites and stalagmites.

Field identification & locations

Identify in the field by its softness (can be scratched by a copper penny or knife) and its strong reaction (bubbling/effervescence) when a small drop of cold dilute hydrochloric acid or vinegar is applied. Found globally in limestone quarries and caves.