mineral

Yellow calcite crystal specimen

Calcite (CaCO₃), likely honey/yellow calcite

AI-generated identification · may be incorrect

Typically Mohs hardness 3, vitreous to pearly luster, translucent yellow coloration, and prominent rhombohedral cleavage; crystals are trigonal, though this piece appears irregularly crystallized or partly broken. Calcite effervesces readily with dilute hydrochloric acid.

Identified September 2, 2026More mineral →

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Physical properties

Formation & geological history

Forms from calcium-carbonate-rich groundwater, hydrothermal fluids, or sedimentary limestone cavities; yellow color commonly results from iron or organic impurities. The specimen’s exact geological age and locality cannot be determined from the image.

Uses & applications

Used in cement, lime, aggregate, chemical production, and as a calcium source; attractive transparent pieces are collected or occasionally used decoratively. This small rough specimen has modest commercial value.

Geological facts

Calcite is one of the most common minerals and is strongly birefringent: a clear fragment can produce doubled lettering when placed over text. Its rhombohedral cleavage distinguishes it from similarly colored quartz, which is harder and lacks cleavage.

Field identification & locations

Likely calcite based on its pale honey-yellow color, blocky cleavage surfaces, and opaque-to-translucent appearance; confirm with a scratch test against a copper coin or knife and an acid reaction. Common worldwide, especially in limestone caves, veins, and geodes.