mineral
Polished brown jasper or chalcedony
Microcrystalline quartz (SiO₂), likely iron-stained jasper/chalcedony
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque to slightly translucent brown with cream-gray banding, vitreous to waxy luster, and no visible cleavage. The smooth surface indicates tumbling or polishing; specific gravity is approximately 2.6.
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Physical properties
Hardness about 6.5–7 Mohs; opaque to slightly translucent brown with cream-gray banding, vitreous to waxy luster, and no visible cleavage. The smooth surface indicates tumbling or polishing; specific gravity is approximately 2.6.
Formation & geological history
Silica-rich groundwater deposited microcrystalline quartz in fractures or cavities, with iron oxides producing the brown color; banding reflects changing fluids and impurities. Formation is typically Phanerozoic, though the host rock may be older.
Uses & applications
Used for cabochons, beads, carvings, decorative objects, and lapidary specimens; it has modest jewelry and collector value.
Geological facts
Jasper is opaque chalcedony colored by iron and other impurities, while more translucent material is classified as chalcedony or agate. Precise identification requires inspection of translucency, banding, and a scratch or hardness test.
Field identification & locations
Commonly found in volcanic and sedimentary terrains, including India, Madagascar, Brazil, Australia, and the western United States. Look for quartz-like hardness, conchoidal fracture, waxy luster, and resistance to scratching by steel.
