mineral

Tumbled pale stone, likely milky quartz or calcite

Quartz (SiO₂) or calcite (CaCO₃); exact identification requires testing

AI-generated identification · may be incorrect

Cream-white, rounded and polished, with a dull to slightly vitreous luster and cloudy internal texture. Quartz has Mohs hardness 7 and no cleavage; calcite has hardness 3, rhombohedral cleavage, and effervesces with dilute acid.

Identified August 12, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed in a hydrothermal vein or carbonate deposit, then naturally or mechanically rounded and polished. The specimen’s geological age cannot be determined visually and depends on its source rock.

Uses & applications

Commonly sold as a tumbled stone for collecting, decoration, and crafts; quartz may be used in glass and electronics, while calcite is important in cement and lime production.

Geological facts

The simplest distinction is a hardness test: quartz scratches glass, whereas calcite generally does not. A drop of dilute hydrochloric acid or vinegar may weakly fizz on calcite, but not quartz.

Field identification & locations

Common worldwide, including Brazil, Mexico, the United States, and Madagascar. Test inconspicuous areas because scratch and acid tests can damage a polished specimen.