mineral

Calcite (with iron oxide staining)

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale. Color: Colorless to white translucent body with reddish-brown iron oxide encrustations. Luster: Vitreous to pearly. Crystal structure: Trigonal/rhombohedral. Cleavage: Perfect rhombohedral in 3 directions. Specific gravity: 2.71.

Hardness: 3 on Mohs scale
Luster: Vitreous to pearly

Identified July 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed in sedimentary, metamorphic, and igneous environments, often precipitating from hydrothermal solutions, marine water, or groundwater enriched in calcium and carbonate ions.

Uses & applications

Used in construction as limestone/marble, production of cement, soil acid neutralizer in agriculture, acid neutralization in chemical industry, and as mineral specimens for collectors.

Geological facts

Calcite displays double refraction (birefringence), where light passing through a clear specimen splits into two rays, causing images seen through it to appear doubled. It effervesces vigorously in cold dilute hydrochloric acid.

Field identification & locations

Identified in the field by its softness (can be scratched by a copper coin or steel knife), perfect rhombohedral cleavage, and strong reaction (fizzing) with dilute acid. Commonly found worldwide in limestone caves, hydrothermal veins, and marble formations.

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