mineral
Tumbled brown jasper or iron-rich chert
Microcrystalline quartz (SiO₂), likely limonite/goethite-stained
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; brown to golden-brown, opaque, with waxy to slightly vitreous luster and no visible cleavage. The rounded, glossy surface and dark porous-looking inclusions suggest natural weathering or tumbling; exact identification requires hardness and streak tests.
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Physical properties
Hardness about 6.5–7 Mohs; brown to golden-brown, opaque, with waxy to slightly vitreous luster and no visible cleavage. The rounded, glossy surface and dark porous-looking inclusions suggest natural weathering or tumbling; exact identification requires hardness and streak tests.
Formation & geological history
Forms when silica-rich fluids replace or cement sediments, with iron oxides staining the quartz brown; commonly Precambrian to younger. The specimen appears water-worn or mechanically polished rather than freshly fractured.
Uses & applications
Used as a decorative stone, lapidary material, cabochons, beads, carvings, and collector specimens; durable jasper is occasionally used for small architectural accents.
Geological facts
Jasper is a variety of opaque chalcedony or chert, and its colors commonly result from hematite, goethite, or limonite. A glass-scratch test and white-streak test can help distinguish it from softer ironstone or slag.
Field identification & locations
Common in gravel beds and silica-rich volcanic or sedimentary terrains worldwide, especially Oregon, California, Arizona, Australia, and Brazil. It should leave no colored streak and should resist scratching by steel.
