mineral

Yellow calcite crystal cluster with calcite fragment

Calcite, calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Typically pale yellow to honey-colored, transparent to translucent, with vitreous-to-pearly luster and prominent rhombohedral cleavage; Mohs hardness 3, trigonal crystal system, specific gravity about 2.71. The elongated piece appears likely calcite, though exact identification is limited by the photograph.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms in limestone cavities, hydrothermal veins, caves, and sedimentary environments through precipitation from calcium-rich fluids; specimens may range from recent cave growth to Paleozoic or younger host-rock ages. Common localities include Mexico, Iceland, Brazil, China, and the United States.

Uses & applications

Used industrially for cement, lime, aggregate, glass, and chemical products; clear or well-formed crystals are collected and occasionally used decoratively. It is generally inexpensive unless exceptionally transparent or unusually crystallized.

Geological facts

Calcite effervesces strongly with dilute hydrochloric acid and shows distinctive rhombohedral cleavage. Clear calcite can display double refraction, making printed text appear doubled through the crystal.

Field identification & locations

Identify by its softness, cleavage, and acid reaction; avoid vinegar as it may react weakly or slowly. The image shows natural crystalline material, possibly with minor iron or other impurities causing the yellow color.