Calcite

Calcite properties at a glance

Geology & background

Forms through evaporation of calcium-rich water, biological processes (shells), or hydrothermal activity.

The defining mineral for 3 on the Mohs hardness scale, calcite has been studied for centuries.

How to identify Calcite

• Check whether the specimen's color and texture match typical Calcite examples.
• Photograph a fresh surface in natural light and avoid shadows, glare, or wet surfaces.
• Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.

Where Calcite is found

Calcite is reported from multiple localities or geological settings. Exact locality should be verified from specimen provenance, maps, or field notes.

How much is Calcite worth?

Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.

Common uses

• Cement production
• Optical instruments
• Collector specimens

Interesting facts

• Clear calcite (Iceland spar) shows double refraction
• Vikings may have used it as a 'sunstone' for navigation
• Forms stalactites and stalagmites in caves

Care & safety

Treat Calcite as a collector specimen unless hardness, cleavage, and fracture are confirmed.

Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a properly rated respirator.

Related rocks & minerals

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