mineral

Tumbled yellow quartz or calcite pebble

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

AI-generated identification · may be incorrect

Smooth, rounded, pale yellow to cream, with a dull-to-waxy luster and fine granular texture. Quartz has Mohs hardness 7 and no cleavage; calcite has hardness 3, prominent rhombohedral cleavage, and fizzes in dilute hydrochloric acid.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Likely a naturally occurring mineral pebble that was mechanically tumbled and polished; yellow color may result from iron staining or included minerals. Its geological age and original host rock cannot be determined from the photograph.

Uses & applications

Common tumbled-stone material for decorative collections, crafts, and inexpensive jewelry; quartz is also important industrially, while calcite is used in cement, lime, and aggregate.

Geological facts

The image alone cannot reliably distinguish quartz from calcite; a steel knife or glass-scratch test is useful, though it may damage the specimen.

Field identification & locations

Test hardness: quartz scratches glass and resists a knife, whereas calcite is easily scratched by a knife and reacts with acid. Similar pebbles occur worldwide in river gravels and commercial lapidary stock.