mineral

Rough white calcite

Calcite (calcium carbonate, CaCO₃)

AI-generated identification · may be incorrect

Likely white to translucent, with a vitreous-to-pearly luster and uneven to cleavage-fractured surfaces. Calcite has Mohs hardness 3 and a trigonal crystal structure; the photo alone cannot confirm it, and similar-looking quartz or feldspar are possible.

Identified September 27, 2026More mineral →

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Physical properties

Formation & geological history

Calcite forms in sedimentary deposits, veins, and cavities through precipitation from calcium-rich water, and in metamorphic rocks such as marble. Its age depends on the deposit and cannot be determined from the image.

Uses & applications

Used in cement and lime production, agriculture, and as a decorative or collecting mineral; clear optical calcite has specialized uses.

Geological facts

Calcite reacts readily with dilute acid, fizzing as it releases carbon dioxide. Its characteristic rhombohedral cleavage can help distinguish it from quartz.

Field identification & locations

Look for relatively soft surfaces, cleavage planes, and acid reaction; common sources include limestone and marble deposits worldwide. A scratch test or acid test on an inconspicuous spot can help confirm identification.