mineral

Tumbled agate or jasper

Microcrystalline quartz (chalcedony), SiO₂, possibly iron-rich jasper

AI-generated identification · may be incorrect

Brown-gold, polished, and slightly translucent with concentric banding and a waxy-to-glassy luster; hardness about 6.5–7 Mohs, no visible cleavage, cryptocrystalline structure, and specific gravity near 2.6. The circular banded pattern may also indicate an orbicular jasper or agate inclusion.

Identified August 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing chalcedony and iron oxides in successive layers; formation commonly occurred during the Cenozoic or older volcanic episodes. The specimen shown is human-tumbled and polished.

Uses & applications

Used for cabochons, beads, carvings, paperweights, and inexpensive collectible stones; attractive patterned pieces may be set in jewelry.

Geological facts

Agate colors and bands result from changing impurities, silica textures, and fluid chemistry during repeated deposition. Iron oxides commonly create the golden-brown coloration.

Field identification & locations

Identify by testing for hardness against steel or glass, examining curved/concentric bands, and looking for waxy luster and lack of cleavage; common sources include Brazil, Uruguay, Madagascar, Mexico, and the western United States.