mineral

Banded calcite tower (often sold as “onyx” or honey calcite)

Calcite, CaCO₃

AI-generated identification · may be incorrect

Hardness 3 Mohs; translucent cream, honey-yellow, pink, and white bands; vitreous to pearly luster; trigonal crystal structure with perfect rhombohedral cleavage; specific gravity about 2.71. The pointed, polished shape is human-worked.

Identified September 2, 2026More mineral →

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Physical properties

Formation & geological history

Formed when calcium-carbonate-rich groundwater precipitated successive layers in caves, hot springs, or carbonate deposits; banding records changing impurities and growth conditions. The specimen’s exact geological age cannot be determined from appearance alone.

Uses & applications

Used decoratively as a polished display stone and sometimes in carvings; it is too soft for durable jewelry and can scratch or etch readily. Common commercial pieces typically sell for about $10–$40, with larger or unusually attractive specimens reaching $50–$100.

Geological facts

“Onyx calcite” is a trade name and is not true silicate onyx; many pieces are marketed as honey calcite or Mexican onyx. Calcite effervesces visibly with dilute hydrochloric acid, though testing a polished specimen may damage it.

Field identification & locations

Commonly sourced from Mexico, Pakistan, Brazil, and Argentina. Identify it by strong horizontal color banding, softness, rhombohedral cleavage, and acid reaction; do not confuse it with harder banded agate or aragonite.