mineral

Tumbled brown agate/chalcedony (probable)

Microcrystalline quartz, SiO₂; likely iron-stained agate or jasper

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; brown, reddish, gray, and cream coloration with faint curved banding; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage. The smooth rounded surface indicates tumbling and polishing.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing successive layers of chalcedony and quartz; coloration commonly comes from iron oxides. Individual specimens may range from Paleozoic to Cenozoic, depending on locality.

Uses & applications

Used as an inexpensive ornamental stone, cabochon, bead, paperweight, or lapidary material. Common polished pieces generally have modest commercial value.

Geological facts

Agate is a variety of chalcedony distinguished by banding, while jasper is more opaque and typically lacks obvious bands. The photograph alone cannot reliably separate agate from jasper or other brown chalcedony.

Field identification & locations

Common worldwide, including Brazil, Uruguay, Mexico, India, Madagascar, and the western United States. Look for translucent edges, curved layering, waxy luster, and resistance to scratching by steel; definitive identification may require a loupe or testing.