mineral

Tumbled agate (likely orbicular or plume agate)

Microcrystalline quartz, SiO₂, with chalcedony banding and inclusions

AI-generated identification · may be incorrect

Polished gray-white stone with rounded, orb-like patterns; quartz hardness 6.5–7, waxy to vitreous luster, trigonal crystal structure at the microscopic scale, and no obvious cleavage. Exact variety cannot be confirmed from the image alone.

Identified October 14, 2026More mineral →

Explore Tumbled agate (likely orbicular or plume agate) in the encyclopedia →

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Physical properties

Formation & geological history

Agate forms as silica-rich fluids fill cavities in volcanic rock, depositing chalcedony in layers over time. Formation ages vary widely, commonly from hundreds of millions of years to younger volcanic settings.

Uses & applications

Used for jewelry, beads, carvings, and decorative objects; also popular with mineral collectors.

Geological facts

Agate’s distinctive patterns arise from successive silica deposits and mineral inclusions; tumbling smooths the surface without changing its geological identity.

Field identification & locations

Look for a hard, smooth surface and translucent-to-opaque chalcedony with curved bands or orb-like inclusions. Agates occur worldwide, including Brazil, Uruguay, India, and the United States.