mineral

Blue-gray calcite (likely cleavage specimen)

Calcite, CaCO₃

AI-generated identification · may be incorrect

Pale blue-gray, translucent to opaque with a vitreous-to-pearly luster and prominent rhombohedral cleavage; Mohs hardness 3. The image shows a rough cluster, but crystal form and composition cannot be confirmed visually.

Identified September 23, 2026More mineral →

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Physical properties

Formation & geological history

Calcite forms in sedimentary, hydrothermal, and metamorphic settings, including limestone cavities and veins; specimens may be geologically recent or hundreds of millions of years old.

Uses & applications

Commonly used in cement and lime production; attractive colored specimens are collected and sometimes used decoratively, but calcite is too soft for most jewelry.

Geological facts

Calcite fizzes in dilute acid and can show double refraction in clear pieces. Blue coloration may reflect trace elements or inclusions.

Field identification & locations

Look for rhombohedral cleavage and low hardness; calcite occurs worldwide, especially in limestone regions and mineral veins. A hardness or acid test can help distinguish it from similar blue-gray minerals.