mineral
Tumbled brecciated jasper (likely ocean or mahogany jasper)
Jasper—microcrystalline quartz/chalcedony, SiO₂, with iron-oxide inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque reddish-brown with dark gray/black mottling, earthy to vitreous luster, and no visible cleavage. Its rounded shape indicates human tumbling and polishing.
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Physical properties
Hardness about 6.5–7 Mohs; opaque reddish-brown with dark gray/black mottling, earthy to vitreous luster, and no visible cleavage. Its rounded shape indicates human tumbling and polishing.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic ash, sediment, or brecciated rock; iron oxides create the red-brown color. Deposits are generally ancient, commonly Precambrian to Mesozoic, depending on locality.
Uses & applications
Used for cabochons, beads, carvings, ornamental objects, and inexpensive lapidary specimens; it has little industrial use beyond decorative stone.
Geological facts
Jasper is a rock rather than a single mineral, composed mainly of cryptocrystalline quartz. The dark patches may be magnetite, manganese oxides, or remnants of the host rock.
Field identification & locations
Identify it by its opacity, fine grain, red-brown iron staining, and inability to scratch with a steel knife easily; glass or quartz can scratch it. Common sources include Madagascar, Indonesia, Mexico, Brazil, and the western United States.