mineral
Polished jasper pebble
Jasper, microcrystalline quartz (SiO₂) with iron-oxide impurities
AI-generated identification · may be incorrectOpaque brown to reddish-brown, fine-grained, waxy-to-glassy luster, no visible crystals or cleavage; Mohs hardness 6.5–7 and specific gravity about 2.55–2.70. The smooth oval form indicates tumbling or polishing.
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Physical properties
Opaque brown to reddish-brown, fine-grained, waxy-to-glassy luster, no visible crystals or cleavage; Mohs hardness 6.5–7 and specific gravity about 2.55–2.70. The smooth oval form indicates tumbling or polishing.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic or sedimentary material, with iron oxides producing the brown-red colors. Individual specimens may range from Precambrian to much younger, depending on the host deposit.
Uses & applications
Used for cabochons, beads, carvings, worry stones, and decorative objects; also collected as an ornamental variety of quartz. Common polished pieces typically have modest value.
Geological facts
Jasper is technically an opaque variety of chalcedony or microcrystalline quartz. Color and pattern names such as picture, ocean, mookaite, or red jasper usually describe appearance or locality rather than separate minerals.
Field identification & locations
Identify it by its opaque, compact texture, lack of cleavage, strong resistance to scratching, and possible red-brown iron staining; it should not scratch easily with a steel knife. Common sources include India, Brazil, Madagascar, Australia, Mexico, and the western United States.
