igneous
Brecciated jasper (likely ocean jasper or rhyolitic jasper)
Silica-rich volcanic breccia composed mainly of microcrystalline quartz/chalcedony (SiO₂), with iron-oxide staining and possible feldspar
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque to slightly translucent, pink, red-brown, cream, and pale blue-gray; waxy to dull luster; irregular angular clasts in a silica-rich matrix, with no obvious cleavage. Specific gravity is approximately 2.5–2.7.
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Physical properties
Hardness about 6.5–7 Mohs; opaque to slightly translucent, pink, red-brown, cream, and pale blue-gray; waxy to dull luster; irregular angular clasts in a silica-rich matrix, with no obvious cleavage. Specific gravity is approximately 2.5–2.7.
Formation & geological history
Formed when silica-rich volcanic rock was fractured and cemented or replaced by chalcedony and quartz, commonly during hydrothermal alteration; typically Cenozoic to older, depending on locality.
Uses & applications
Used as a lapidary stone for cabochons, carvings, polished slabs, and ornamental objects; attractive examples are collectible but generally not a major industrial material.
Geological facts
The angular multicolored fragments and reddish iron-oxide matrix are characteristic of brecciated jasper. The specimen may be marketed as ocean jasper if sourced from Madagascar, but locality confirmation is required.
Field identification & locations
Identify by its opaque silica-rich body, mosaic-like angular fragments, waxy luster, and inability to scratch with a steel knife; quartz or glass should scratch it. Common sources include Madagascar, Indonesia, Mexico, and the western United States.
