mineral
Tumbled jasper or jasper-rich chert
Microcrystalline quartz (SiO₂) with iron-oxide impurities
AI-generated identification · may be incorrectOpaque, rounded and polished, with reddish-brown, gray, and dark patches; vitreous to waxy luster and no visible cleavage. Mohs hardness is about 6.5–7; density is approximately 2.6 g/cm³, and the texture is cryptocrystalline.
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Physical properties
Opaque, rounded and polished, with reddish-brown, gray, and dark patches; vitreous to waxy luster and no visible cleavage. Mohs hardness is about 6.5–7; density is approximately 2.6 g/cm³, and the texture is cryptocrystalline.
Formation & geological history
Forms when silica-rich groundwater replaces or fills cavities in volcanic or sedimentary rocks, with iron oxides producing the red-brown coloration. Its exact geological age and locality cannot be determined from the photograph.
Uses & applications
Used for tumbled stones, cabochons, beads, carvings, and ornamental objects; attractive pieces are popular with collectors but have modest commercial value.
Geological facts
Jasper is a variety of opaque chalcedony or microcrystalline quartz, and its vivid patterns commonly result from hematite or goethite inclusions.
Field identification & locations
Identify it by its opaque appearance, iron-red coloration, waxy polish, and resistance to scratching; it should scratch glass but not be scratched by a steel knife. Common sources include India, Madagascar, Brazil, Australia, and the western United States.
