mineral
Milky calcite
Calcite (CaCO₃), likely a cleavage fragment
AI-generated identification · may be incorrectWhite to translucent, vitreous-to-pearly luster, prominent rhombohedral cleavage, and hardness Mohs 3; commonly shows curved or stepped cleavage surfaces and moderate density (specific gravity ~2.71).
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Physical properties
White to translucent, vitreous-to-pearly luster, prominent rhombohedral cleavage, and hardness Mohs 3; commonly shows curved or stepped cleavage surfaces and moderate density (specific gravity ~2.71).
Formation & geological history
Forms when calcium carbonate precipitates from groundwater or hydrothermal fluids, and in limestone, marble, and cave deposits; the specimen’s precise geological age cannot be determined from the image.
Uses & applications
Used in cement, lime, aggregate, glass manufacture, agriculture, and chemical processing; clear optical calcite is collectible, while ordinary pieces have little commercial value.
Geological facts
Calcite effervesces visibly in dilute hydrochloric acid or strong vinegar, unlike quartz; transparent Iceland spar can display double refraction.
Field identification & locations
The blocky translucent appearance and excellent cleavage favor calcite over quartz, which lacks cleavage and is harder. Common worldwide, especially in limestone regions, hydrothermal veins, and caves.
