mineral

Polished jasper or chert

Microcrystalline quartz (SiO₂), likely iron-stained jasper/chalcedony

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; olive-green, brown, cream, and gray banding with a waxy to subdued vitreous luster. Dense, cryptocrystalline, with no visible cleavage and conchoidal fracture; exact identification is uncertain from the image.

Identified August 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or fills cavities in volcanic or sedimentary rocks, with iron and other impurities creating the colors and patterns. Deposits may range from Paleozoic to recent geological ages.

Uses & applications

Used for cabochons, beads, carvings, tumbled stones, and ornamental objects; too small for construction use.

Geological facts

The irregular flowing bands and opaque body are typical of jasper or silicified rock rather than transparent agate. A polished surface can obscure the original host rock.

Field identification & locations

Common in volcanic and sedimentary terrains worldwide, including Oregon, California, Arizona, Australia, and Brazil. It should resist a steel file and may scratch glass; an unglazed edge or specific-gravity test helps distinguish it from glass or plastic.