mineral

Likely calcite crystal fragment

Calcite (CaCO₃), probably a rhombohedral cleavage fragment

AI-generated identification · may be incorrect

Pale gray-green to translucent with vitreous to pearly luster and prominent stepped/rhombohedral cleavage; Mohs hardness 3, specific gravity about 2.71. The blocky faces and translucent yellowish edge fit calcite better than quartz.

Identified August 23, 2026More mineral →

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Physical properties

Formation & geological history

Calcite commonly forms in hydrothermal veins, limestone cavities, and sedimentary rocks through precipitation from calcium-rich fluids; specimens may range from recent to hundreds of millions of years old.

Uses & applications

Used industrially for cement, lime, aggregate, glass, and soil treatment; transparent crystals are collector specimens, though this small fragment has little jewelry value.

Geological facts

Calcite effervesces vigorously in dilute hydrochloric acid or strong vinegar, unlike quartz. It commonly shows double refraction when clear and can fluoresce under ultraviolet light.

Field identification & locations

Identify by rhombohedral cleavage, softness, and acid reaction; common worldwide, especially in Mexico, Iceland, the United States, and China. Avoid scratching it with steel if preservation matters.