mineral
Tumbled brown agate
Microcrystalline quartz (SiO₂), variety of chalcedony
AI-generated identification · may be incorrectPolished, translucent brown chalcedony with darker inclusions or cavities; Mohs hardness 6.5–7, waxy to vitreous luster, trigonal quartz structure, no visible cleavage, and specific gravity about 2.6.
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Physical properties
Polished, translucent brown chalcedony with darker inclusions or cavities; Mohs hardness 6.5–7, waxy to vitreous luster, trigonal quartz structure, no visible cleavage, and specific gravity about 2.6.
Formation & geological history
Silica-rich groundwater deposited chalcedony in rock cavities, often with iron compounds producing brown colors; the exact age and locality cannot be determined from the image.
Uses & applications
Used in jewelry, decorative objects, and mineral collections; small tumbled stones are commonly sold as curios.
Geological facts
Agate is prized for its varied colors and patterns, though this specimen’s polished surface and limited view obscure any distinctive banding.
Field identification & locations
Look for hardness, waxy luster, and translucent edges; agate occurs worldwide, commonly in volcanic rocks and some sedimentary formations. Similar small tumbled pieces typically sell for about $2–$15 USD.
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