Calcite

Physical Properties

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

Formation & Geological History

Formed in sedimentary environments through chemical precipitation or as a biological byproduct in marine settings. It is also found in metamorphic marble and igneous carbonatites. It has been forming throughout Earth's history across all geological ages.

Uses & Applications

Used in the manufacturing of cement and mortar, as a soil conditioner in agriculture, in the production of lime, and occasionally as a decorative stone or for acid neutralization in the chemical industry.

Geological Facts

Calcite is one of the most common minerals on Earth. It exhibits a famous property called double refraction, where light passing through a clear specimen splits into two rays, causing objects viewed through it to appear doubled.

Field Identification & Locations

Can be identified in the field by its 3-way rhombohedral cleavage and its vigorous effervescence (bubbling) when a drop of dilute hydrochloric acid is applied. It is common in limestone regions and cave systems.

Identified on: 4/13/2026

Mode: Standard