mineral
Tumbled red jasper
Jasper, microcrystalline quartz (SiO₂)
AI-generated identification · may be incorrectOpaque brick-red to reddish-brown, with a matte-to-waxy luster and subtle pale mottling; hardness about 6.5–7 Mohs, trigonal microcrystalline structure, no cleavage, and specific gravity around 2.5–2.7. The rounded form indicates tumbling or natural water wear.
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Physical properties
Opaque brick-red to reddish-brown, with a matte-to-waxy luster and subtle pale mottling; hardness about 6.5–7 Mohs, trigonal microcrystalline structure, no cleavage, and specific gravity around 2.5–2.7. The rounded form indicates tumbling or natural water wear.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement sediments, commonly incorporating iron oxides that produce the red color. Deposits occur in many ages, from Precambrian formations to younger volcanic and sedimentary environments.
Uses & applications
Used for beads, cabochons, carvings, polished stones, and ornamental objects; historically used for tools and small sculptures. Common tumbled pieces have modest collector value.
Geological facts
Its red color is chiefly caused by hematite or other iron oxides, while the fine texture reflects chalcedonic or microcrystalline quartz. It is often confused with red chert, which is compositionally similar.
Field identification & locations
Identify by its opaque red-brown color, uniform fine grain, glassy-to-waxy surface, and inability to scratch it with a steel knife easily. Common sources include India, Madagascar, Brazil, Australia, South Africa, and the western United States.
