mineral

Milky calcite specimen

Calcite (calcium carbonate, CaCO₃)

AI-generated identification · may be incorrect

Typically white to translucent with vitreous-to-pearly luster, prominent rhombohedral cleavage, and hardness 3 on the Mohs scale; crystals are trigonal, with specific gravity about 2.71. The layered, blocky cleavage and translucent appearance strongly suggest calcite, though exact identification would require testing.

Identified August 10, 2026More mineral →

Explore Milky calcite specimen in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Calcite commonly forms in limestone, hydrothermal veins, caves, and carbonate-rich cavities by precipitation from groundwater or hot fluids. Individual specimens may form at many ages, from modern cave deposits to ancient sedimentary and hydrothermal systems.

Uses & applications

Used extensively in cement, lime, aggregate, soil treatment, and chemical manufacturing; transparent varieties are collectible, but this rough specimen has modest gem value.

Geological facts

Calcite effervesces visibly in dilute hydrochloric acid and may weakly react with household vinegar if powdered. Its double refraction is especially clear through transparent fragments.

Field identification & locations

Look for rhombohedral cleavage, low hardness, and acid reaction; it can be scratched by a copper coin or knife. Common sources include Mexico, the United States, Iceland, and China.