mineral
Red jasper
Microcrystalline quartz (SiO₂), commonly colored by iron oxides
AI-generated identification · may be incorrectOpaque brick-red to brown, earthy-to-waxy luster, hardness about 6.5–7 Mohs, no visible cleavage, conchoidal to uneven fracture, and typically fine-grained cryptocrystalline structure. The specimen appears naturally weathered or roughly polished, with darker iron-rich patches.
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Physical properties
Opaque brick-red to brown, earthy-to-waxy luster, hardness about 6.5–7 Mohs, no visible cleavage, conchoidal to uneven fracture, and typically fine-grained cryptocrystalline structure. The specimen appears naturally weathered or roughly polished, with darker iron-rich patches.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement fine sediments, often in volcanic or hydrothermal environments; its age depends on the host formation and may range from Precambrian to younger. Iron oxide inclusions produce the red coloration.
Uses & applications
Used for cabochons, beads, carvings, tumbled stones, ornaments, and decorative stone; less commonly used as aggregate or facing material. Its value is primarily ornamental and collectible.
Geological facts
Jasper is a variety of chalcedony or microcrystalline quartz, although the term is often used broadly for opaque silica-rich rocks. Brecciated, orbicular, and scenic varieties are especially sought after.
Field identification & locations
Identify it by its opaque red-brown color, high hardness, fine texture, and inability to scratch with a steel knife easily; a quartz streak test or silica hardness comparison helps confirm it. Common localities include India, Madagascar, Brazil, Australia, South Africa, and the western United States.
