mineral
Tumbled jasper or iron-rich chert fragments
Jasper/chert, predominantly microcrystalline quartz (SiO₂) with iron-oxide inclusions
AI-generated identification · may be incorrectTypically opaque reddish-brown to orange, with earthy-to-waxy luster and no visible cleavage; Mohs hardness about 6.5–7, conchoidal fracture, and specific gravity near 2.6. The pieces appear polished or naturally rounded and strongly colored by hematite/goethite.
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Physical properties
Typically opaque reddish-brown to orange, with earthy-to-waxy luster and no visible cleavage; Mohs hardness about 6.5–7, conchoidal fracture, and specific gravity near 2.6. The pieces appear polished or naturally rounded and strongly colored by hematite/goethite.
Formation & geological history
Forms when silica-rich groundwater replaces or fills sediment, producing microcrystalline quartz later stained by iron oxides; deposits range from Precambrian to recent. Common sources include volcanic and sedimentary terrains worldwide.
Uses & applications
Used for cabochons, beads, carvings, lapidary practice, and decorative stone; less commonly as aggregate. Small ordinary pieces have modest collecting value.
Geological facts
Jasper is a variety of opaque chalcedony/chert rather than a single mineral species. Red coloration generally reflects hematite, while yellow-orange tones may reflect goethite or limonite.
Field identification & locations
Identify by testing for glass-scratching hardness, dense opaque appearance, lack of fizz in dilute acid, and conchoidal fracture; exact variety requires locality or laboratory analysis. Common in Brazil, India, Madagascar, Australia, and the western United States.
