mineral

Blue calcite

Calcite (CaCO₃), likely blue variety

AI-generated identification · may be incorrect

Typically pale blue to blue-gray, translucent to opaque, with a vitreous to pearly luster and rhombohedral cleavage; Mohs hardness 3 and specific gravity about 2.71. The rough, blocky piece shows cleavage surfaces and possible white calcite veining.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms in limestone, hydrothermal veins, cavities, and sedimentary carbonate deposits through precipitation from calcium-rich fluids. Blue coloration commonly reflects trace impurities or inclusions; exact age cannot be determined from the image.

Uses & applications

Used mainly as a collector specimen, ornamental stone, and occasionally for decorative objects; it is too soft for most durable jewelry. It may also be used industrially as carbonate material, though attractive blue specimens are generally retained for collecting.

Geological facts

Calcite effervesces strongly with dilute hydrochloric acid and displays rhombohedral cleavage rather than right-angle cleavage. It has pronounced birefringence: clear fragments can make text appear doubled.

Field identification & locations

Commonly found in Mexico, Madagascar, Peru, the United States, and China; identify by softness, cleavage, acid reaction, and blue color. The specimen could also be blue fluorite, but the apparent cleavage and texture favor calcite; testing is recommended.