mineral
Calcite crystal cluster
Calcite — calcium carbonate, CaCO₃
AI-generated identification · may be incorrectWhite to colorless, vitreous to pearly luster, commonly rhombohedral or scalenohedral crystals; Mohs hardness 3, perfect rhombohedral cleavage, and specific gravity about 2.71. The specimen appears to be a rough cluster of intergrown translucent calcite crystals.
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Physical properties
White to colorless, vitreous to pearly luster, commonly rhombohedral or scalenohedral crystals; Mohs hardness 3, perfect rhombohedral cleavage, and specific gravity about 2.71. The specimen appears to be a rough cluster of intergrown translucent calcite crystals.
Formation & geological history
Forms in hydrothermal veins, limestone cavities, caves, and sedimentary deposits when calcium-rich fluids precipitate carbonate minerals. It may range from modern cave growth to Paleozoic or younger host-rock mineralization; age cannot be determined from the image.
Uses & applications
Used extensively in cement, lime, construction aggregate, glass, agriculture, and chemical manufacture; attractive transparent crystals are collected but are generally inexpensive.
Geological facts
Calcite strongly effervesces with dilute hydrochloric acid and displays birefringence, producing a doubled image through clear pieces. Its crystal shapes and cleavage distinguish it from quartz.
Field identification & locations
Common worldwide, especially in limestone regions, hydrothermal veins, and mines; notable localities include Mexico, Iceland, England, and the United States. Test gently with a steel blade for softness and use acid only on an inconspicuous area.
