igneous
Tumbled jasper
Microcrystalline quartz (chalcedony), predominantly SiO₂, with iron-oxide inclusions
AI-generated identification · may be incorrectOpaque, polished stone with orange-brown, cream, and yellow mottling; Mohs hardness 6.5–7, vitreous to waxy luster, cryptocrystalline structure, no visible cleavage, and typical specific gravity around 2.6. The rusty colors indicate hematite or limonite staining.
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Physical properties
Opaque, polished stone with orange-brown, cream, and yellow mottling; Mohs hardness 6.5–7, vitreous to waxy luster, cryptocrystalline structure, no visible cleavage, and typical specific gravity around 2.6. The rusty colors indicate hematite or limonite staining.
Formation & geological history
Jasper forms when silica-rich groundwater replaces or fills cavities in volcanic or sedimentary rock, incorporating iron oxides and other impurities; individual pieces may range from Paleozoic to Cenozoic in age. This specimen has been cut or naturally rounded and mechanically tumbled.
Uses & applications
Used for cabochons, beads, carvings, decorative stones, and lapidary collections; historically used for tools and ornamental objects. It has little industrial value compared with ordinary quartz.
Geological facts
Jasper is an opaque variety of chalcedony, unlike transparent agate. Its patterns and colors vary widely according to trace minerals and the original host rock.
Field identification & locations
Identify it by its opacity, fine grain, waxy polish, hardness, and iron-red coloration; it should resist scratching by a steel knife. Common sources include the western United States, Madagascar, Brazil, India, and Australia.
