igneous
Brecciated jasper/chalcedony (likely rhyolitic or volcanic breccia)
Silica-rich breccia composed mainly of microcrystalline quartz (chalcedony/jasper), with iron oxides and altered volcanic fragments
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; mottled cream, brown, pink, gray, and reddish colors; waxy to dull luster; mostly massive, with no obvious cleavage. The angular fragments and silica-rich matrix indicate brecciation and silicification.
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Physical properties
Hardness about 6.5–7 Mohs; mottled cream, brown, pink, gray, and reddish colors; waxy to dull luster; mostly massive, with no obvious cleavage. The angular fragments and silica-rich matrix indicate brecciation and silicification.
Formation & geological history
Likely formed when volcanic rock fragments were cemented and later replaced by silica-bearing fluids, with iron oxides producing the red-brown coloration. Such material is generally Cenozoic to older, depending on its locality.
Uses & applications
Used as lapidary rough, cabochons, polished stones, beads, and ornamental objects; attractive pieces have modest collector value.
Geological facts
The specimen’s irregular angular clasts, contrasting colors, and chalcedony-like patches are characteristic of brecciated jasper rather than a single crystal mineral.
Field identification & locations
Identify it by its very fine-grained silica texture, strong toughness, lack of cleavage, and mottled breccia pattern; common sources include volcanic terrains in Oregon, Idaho, Nevada, Mexico, and Australia. Exact identification requires locality data or testing.
