mineral

Polished yellow chalcedony (likely lemon quartz/calcite alternative)

Microcrystalline quartz, SiO₂ (chalcedony); exact identification requires testing

AI-generated identification · may be incorrect

Smooth tumbled cabochon, pale yellow, translucent to opaque, waxy-to-glassy luster; quartz hardness 7, no cleavage, specific gravity about 2.60. The unusually soft-looking appearance could also indicate calcite (hardness 3) or dyed stone.

Identified August 18, 2026More mineral →

Explore Polished yellow chalcedony (likely lemon quartz/calcite alternative) in the encyclopedia →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; deposits range from Precambrian to recent. Yellow color may result from iron staining or treatment.

Uses & applications

Used for cabochons, beads, carvings, and lapidary collections; ordinary pieces have modest value.

Geological facts

A steel knife will not scratch quartz chalcedony but may scratch calcite; quartz does not fizz in dilute hydrochloric acid, whereas calcite fizzes strongly.

Field identification & locations

Common sources include Brazil, Uruguay, India, Madagascar, and the United States. Confirm with hardness, streak, specific gravity, and a refractive-index test; visual identification alone is uncertain.