mineral
Yellow jasper (likely polished/tumbled)
Jasper, microcrystalline quartz (SiO₂), commonly colored by iron oxides
AI-generated identification · may be incorrectOpaque mustard-yellow to orange with cream and brown mottling; waxy to dull luster and no visible crystals. Hardness about 6.5–7 Mohs, conchoidal fracture, quartz-like specific gravity near 2.6; apparent rounded edges indicate tumbling or polishing.
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Physical properties
Opaque mustard-yellow to orange with cream and brown mottling; waxy to dull luster and no visible crystals. Hardness about 6.5–7 Mohs, conchoidal fracture, quartz-like specific gravity near 2.6; apparent rounded edges indicate tumbling or polishing.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic ash, sediments, or other rocks, with iron oxides producing the yellow-orange color. Deposits occur in many ages and settings, so the specimen’s geological age cannot be determined visually.
Uses & applications
Used for beads, cabochons, carvings, polished stones, and decorative objects; durable jasper is occasionally used for small ornamental surfaces. Common tumbled pieces generally have modest commercial value.
Geological facts
Jasper is a variety of chalcedony or cryptocrystalline quartz, though the term is often applied broadly to opaque silica-rich rocks. Color patterns are controlled largely by iron minerals and included host material.
Field identification & locations
Identify it by its opacity, fine-grained texture, hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include India, Madagascar, Brazil, Australia, Mexico, and the United States.
