mineral
Tumbled red jasper (likely brecciated jasper)
Jasper, microcrystalline quartz (SiO₂) with iron-oxide inclusions
AI-generated identification · may be incorrectOpaque reddish-brown to black, vitreous-to-waxy luster, polished surface, and irregular brecciation or matrix patterns. Mohs hardness 6.5–7; no visible cleavage; specific gravity about 2.5–2.7; cryptocrystalline quartz structure.
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Physical properties
Opaque reddish-brown to black, vitreous-to-waxy luster, polished surface, and irregular brecciation or matrix patterns. Mohs hardness 6.5–7; no visible cleavage; specific gravity about 2.5–2.7; cryptocrystalline quartz structure.
Formation & geological history
Forms when silica-rich fluids replace or cement fine-grained sediments or volcanic material, with iron oxides producing the red color. Deposits occur in many ages, commonly in hydrothermal and volcanic terrains.
Uses & applications
Used for cabochons, beads, carvings, tumbled stones, and ornamental objects; too small a piece for construction use. Common polished specimens generally have modest collector value.
Geological facts
Jasper is an opaque variety of chalcedony or microcrystalline quartz, and its patterns are caused by impurities, brecciation, or mineral replacement. The dark areas may be manganese or iron-rich matrix rather than separate crystals.
Field identification & locations
Identify it by its opaque red-brown color, black inclusions, glassy polish, and inability to scratch with a steel knife easily; glassy red slag can look similar. Common sources include India, Madagascar, Brazil, the United States, and Australia.
