metamorphic
Polished yellow jasper
Jasper, microcrystalline quartz (SiO₂) with iron-oxide impurities
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque mustard-yellow, honey, tan, and reddish-brown coloration with brown/black specks; waxy to vitreous luster and no visible cleavage. Dense, fine-grained cryptocrystalline quartz; the surface appears polished and naturally fractured.
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Physical properties
Hardness about 6.5–7 Mohs; opaque mustard-yellow, honey, tan, and reddish-brown coloration with brown/black specks; waxy to vitreous luster and no visible cleavage. Dense, fine-grained cryptocrystalline quartz; the surface appears polished and naturally fractured.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic ash, sediments, or other rocks, with iron oxides producing the yellow-red colors. Deposits occur in many geological ages, commonly in volcanic and sedimentary terrains.
Uses & applications
Used for cabochons, carvings, beads, tumbled stones, and ornamental objects; occasionally as decorative stone. Typical value is approximately $10–$50 for a hand-sized polished piece, higher for distinctive patterns or provenance.
Geological facts
Its color commonly reflects limonite, goethite, or hematite inclusions. Jasper is a variety of chalcedony/microcrystalline quartz, though the term is used broadly for opaque silica-rich material.
Field identification & locations
Identify it by its opaque appearance, fine texture, waxy polish, lack of cleavage, and inability to scratch it with a steel knife easily; quartz or glass should scratch it. Common sources include India, Madagascar, Brazil, Australia, and the western United States.
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