mineral

Tumbled yellow-brown chalcedony (likely agate)

Microcrystalline quartz, SiO₂; chalcedony, possibly iron-stained agate

AI-generated identification · may be incorrect

Smooth, opaque-to-translucent yellow-brown surface with darker inclusions and a polished luster. Quartz has Mohs hardness 7, trigonal crystal structure at the microscopic level, no cleavage, and specific gravity about 2.6; the exact identity cannot be confirmed from the photo alone.

Identified October 16, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited quartz in rock cavities, with iron compounds likely causing the brown-yellow color; the specimen was later rounded and polished. Chalcedony forms in many ages and geological settings.

Uses & applications

Commonly used for jewelry, ornaments, and lapidary collecting; agate varieties are also used for beads and decorative objects.

Geological facts

Chalcedony is made of extremely fine quartz crystals, so its texture appears smooth rather than visibly crystalline.

Field identification & locations

Look for waxy luster, hardness near 7, and possible banding or translucent edges; this piece may be a naturally colored tumbled pebble. Chalcedony occurs worldwide, including Brazil, India, and the western United States.