mineral
Tumbled brown jasper
Microcrystalline quartz/chalcedony (SiO₂), likely iron-stained jasper
AI-generated identification · may be incorrectOpaque brown to olive-brown, mottled with lighter patches; vitreous to waxy polish, no visible cleavage, hardness about 6.5–7 Mohs, specific gravity roughly 2.6. Its rounded shape and glossy surface indicate tumbling and polishing.
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Physical properties
Opaque brown to olive-brown, mottled with lighter patches; vitreous to waxy polish, no visible cleavage, hardness about 6.5–7 Mohs, specific gravity roughly 2.6. Its rounded shape and glossy surface indicate tumbling and polishing.
Formation & geological history
Jasper forms when silica-rich groundwater replaces or cements fine sediments, commonly incorporating iron oxides and other impurities that create brown coloration. Most specimens are Cenozoic or older, depending on the deposit.
Uses & applications
Used as an inexpensive ornamental stone, cabochon, bead, paperweight, and lapidary material; rarely used for aggregate or decorative stone.
Geological facts
Jasper is an opaque variety of chalcedony rather than a single mineral species; color and pattern depend on included hematite, goethite, clay, and other minerals.
Field identification & locations
Identify it by its opacity, fine-grained texture, earthy mottling, glassy polish, and inability to scratch with a steel knife (though testing can damage it). Common sources include India, Madagascar, Brazil, Australia, and the western United States.
