mineral

Yellow calcite (rough crystal)

Calcite, CaCO₃

AI-generated identification · may be incorrect

Pale yellow, translucent to cloudy, with a vitreous-to-pearly luster and prominent rhombohedral cleavage; Mohs hardness 3. The small, rounded-looking piece appears naturally rough or partly broken, but the image alone cannot confirm its exact identity.

Identified October 6, 2026More mineral →

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Physical properties

Formation & geological history

Calcite forms in sedimentary carbonate rocks, hydrothermal veins, and cavities as mineral-rich fluids precipitate calcium carbonate. Its age and specific formation setting cannot be determined from the photograph.

Uses & applications

Commonly used in cement, lime, and other industrial products; attractive clear or colored crystals are collected and sometimes used decoratively. This small specimen is more likely a teaching or collector sample than a gemstone.

Geological facts

Calcite fizzes in dilute hydrochloric acid and is readily scratched by a copper coin or steel knife. Its characteristic double refraction is easiest to see through clear, transparent pieces.

Field identification & locations

Look for softness, rhombohedral cleavage, and acid effervescence; yellow color alone is not diagnostic. Calcite occurs worldwide, especially in limestone and marble regions.