mineral
Polished jasper or chert
Microcrystalline quartz (SiO₂), likely iron-stained jasper/chalcedony
AI-generated identification · may be incorrectHardness 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.
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Physical properties
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.
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.
