mineral

Tumbled chalcedony (possibly agate)

Microcrystalline quartz, SiO₂ (chalcedony); banding is not clearly visible to confirm agate

AI-generated identification · may be incorrect

Brown-gray, translucent to opaque, with a waxy to vitreous luster and conchoidal fracture; quartz hardness is about 7 Mohs. The rounded shape suggests it has been tumbled or naturally worn.

Identified October 4, 2026More mineral →

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Physical properties

Brown-gray, translucent to opaque, with a waxy to vitreous luster and conchoidal fracture; quartz hardness is about 7 Mohs. The rounded shape suggests it has been tumbled or naturally worn.

Formation & geological history

Silica-rich fluids deposited microcrystalline quartz in cavities or fractures, commonly in volcanic rocks; chalcedony forms across many geological ages.

Uses & applications

Used for beads, cabochons, carvings, and ornamental objects; lower-grade pieces are popular for tumbling and collecting.

Geological facts

Agate is a banded variety of chalcedony, but no distinct bands are evident in this view.

Field identification & locations

Look for hardness near 7, a waxy luster, and curved fracture surfaces; agate identification is strengthened by visible bands when held to light. Chalcedony occurs worldwide, including Brazil, India, and the western United States.