mineral

Tumbled brown agate (chalcedony)

Microcrystalline quartz, SiO₂; likely iron-stained chalcedony, though the photo alone cannot confirm agate banding

AI-generated identification · may be incorrect

Brown to amber, mottled, with a waxy-to-glassy polish; quartz crystal structure is too fine-grained to see. Hardness is about 6.5–7 Mohs, with no prominent cleavage and conchoidal fracture; specific gravity is about 2.6.

Identified October 16, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited chalcedony in cavities or fractures, often in volcanic rocks; iron oxides can produce brown coloration. The specimen’s age and source cannot be determined from the image.

Uses & applications

Tumbled pieces are used in jewelry, crafts, and collections; agate is also used for ornamental objects and, historically, precision components.

Geological facts

Agate is a variety of chalcedony, but visible curved or parallel bands are the most reliable visual clue for identifying it specifically.

Field identification & locations

A small, rounded, polished brown stone with waxy luster is consistent with tumbled chalcedony; agates occur worldwide, including Brazil, Uruguay, India, and the western United States. Look for banding or inspect a fresh surface to distinguish it from other brown stones.