mineral

Clear calcite crystal fragment

Calcite (calcium carbonate, CaCO₃)

AI-generated identification · may be incorrect

Typically colorless to white, translucent, and vitreous to pearly, with prominent rhombohedral cleavage; Mohs hardness 3, trigonal crystal system, and specific gravity about 2.71. The specimen appears to show stepped cleavage surfaces and possible iron-oxide staining.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Calcite commonly precipitates from groundwater, hydrothermal fluids, and marine sediments, forming veins, cavities, limestone, and marble; individual crystals may be geologically young or millions to hundreds of millions of years old.

Uses & applications

Used to manufacture cement, lime, glass, and agricultural soil amendments; clear crystals are collected, and optical-grade calcite has specialized applications.

Geological facts

Calcite strongly effervesces with dilute hydrochloric acid and displays double refraction, splitting printed text viewed through a clear fragment.

Field identification & locations

Common worldwide in limestone and hydrothermal veins, especially Mexico, Iceland, the United States, and China. Confirm with a vinegar/acid test and scratch test, while avoiding damage to valuable specimens.