mineral
Tumbled brecciated jasper (likely ocean jasper or red-and-gray jasper)
Microcrystalline quartz/chalcedony (SiO₂) with iron-oxide hematite/goethite and dark volcanic-mineral inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque, multicolored red, gray, cream, and black; polished vitreous to waxy luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The rounded shape indicates tumbling or natural water abrasion.
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Physical properties
Hardness about 6.5–7 Mohs; opaque, multicolored red, gray, cream, and black; polished vitreous to waxy luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The rounded shape indicates tumbling or natural water abrasion.
Formation & geological history
Forms when silica-rich fluids cement or replace volcanic and sedimentary material, with iron oxides producing red coloration; some ocean jasper formed in Miocene volcanic settings near Madagascar. Exact age and locality cannot be confirmed from the photograph.
Uses & applications
Used for cabochons, beads, carvings, polished stones, and decorative objects; common tumbled pieces generally have modest collector value.
Geological facts
The specimen appears brecciated, meaning angular fragments were later cemented by silica. Red coloration commonly reflects hematite, while gray-black areas may represent altered volcanic rock or manganese-rich material.
Field identification & locations
Identify by its opaque patterned body, very high hardness, lack of cleavage, and inability to scratch with a steel knife; quartz-rich jasper commonly scratches glass. Common sources include Madagascar, Brazil, India, Mexico, and the western United States.
