mineral
Tumbled brecciated jasper or quartz-rich rock
Brecciated chalcedony/jasper, chiefly microcrystalline SiO₂ with iron-oxide or clay-rich matrix
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; rounded, polished pebble with cream-white angular fragments in a gray-green to brown matrix, waxy to dull luster, and no visible cleavage. Exact identification is uncertain from the photograph alone.
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Physical properties
Hardness about 6.5–7 Mohs; rounded, polished pebble with cream-white angular fragments in a gray-green to brown matrix, waxy to dull luster, and no visible cleavage. Exact identification is uncertain from the photograph alone.
Formation & geological history
Forms when silica-rich material, commonly chalcedony or jasper, fractures and is cemented by later silica or iron-bearing fluids; ages vary widely by deposit. Tumbling has smoothed and polished the specimen.
Uses & applications
Used as an inexpensive lapidary and decorative stone for cabochons, beads, carvings, and display specimens; generally not used structurally.
Geological facts
The contrasting angular patches indicate brecciation rather than ordinary uniform jasper. A glassy appearance and conchoidal fracture would support chalcedony; earthy opacity suggests jasper.
Field identification & locations
Commonly found in volcanic terrains, hydrothermal veins, and sedimentary silica deposits, including the western United States, Mexico, Madagascar, and Australia. Test cautiously for a glass-scratching hardness and inspect fresh edges; acid testing is unnecessary.
