Rock Identifier
Pale green calcite crystal (Calcite (CaCO₃), likely a translucent cleavage fragment) — mineral
mineral

Pale green calcite crystal

Calcite (CaCO₃), likely a translucent cleavage fragment

AI-generated identification · may be incorrect

Typically Mohs hardness 3, vitreous to pearly luster, colorless to pale green, and excellent rhombohedral cleavage; calcite is trigonal and has specific gravity about 2.71. The visible stepped, non-cubic break surfaces and translucency are consistent with calcite, though image-only identification is provisional.

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Physical properties

Typically Mohs hardness 3, vitreous to pearly luster, colorless to pale green, and excellent rhombohedral cleavage; calcite is trigonal and has specific gravity about 2.71. The visible stepped, non-cubic break surfaces and translucency are consistent with calcite, though image-only identification is provisional.

Formation & geological history

Forms in limestone, marble, hydrothermal veins, caves, and sedimentary cavities; green color may result from trace metals or inclusions. Individual crystals can form from very recent to Precambrian geological settings.

Uses & applications

Used extensively for cement, lime, aggregate, soil treatment, and optical/calcareous materials; attractive transparent crystals are collected, but this small rough piece has modest value.

Geological facts

Calcite effervesces strongly with dilute hydrochloric acid or vinegar, though vinegar may react slowly. It shows birefringence: printed text viewed through a clear fragment may appear doubled.

Field identification & locations

Common worldwide, including Mexico, Iceland, the United States, and China. Confirm with a steel knife or copper coin scratch test and acid fizz; avoid confusing it with fluorite, which has cubic cleavage and hardness 4.