mineral

Yellow chalcedony (likely tumbled)

Microcrystalline quartz, SiO₂; possibly yellow jasper or calcite

AI-generated identification · may be incorrect

Small rounded, opaque-to-translucent yellow specimen with waxy to dull luster and no visible crystals; likely hardness about 6.5–7 Mohs if chalcedony (calcite would be 3). Specific gravity is typically ~2.6. Identification is uncertain from the photo alone.

Identified September 18, 2026More mineral →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; yellow color may result from iron staining. Deposits occur worldwide, especially Brazil, Uruguay, India, Madagascar, and the United States.

Uses & applications

Used as a lapidary stone for cabochons, beads, carvings, and tumbled specimens; quality and translucency determine jewelry value.

Geological facts

A steel file or knife should not easily scratch chalcedony, while calcite scratches readily; vinegar may weakly fizz on calcite but not quartz.

Field identification & locations

Look for waxy luster, conchoidal fracture, lack of cleavage, and resistance to scratching by steel. A streak, hardness, and acid test would distinguish chalcedony from yellow calcite or jasper.