mineral
Tumbled brown jasper (probable)
Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide impurities
AI-generated identification · may be incorrectOpaque dark brown to reddish-brown, smooth polished surface, vitreous-to-waxy luster, and no visible crystals or cleavage. Hardness is approximately 6.5–7 Mohs; specific gravity about 2.6.
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Physical properties
Opaque dark brown to reddish-brown, smooth polished surface, vitreous-to-waxy luster, and no visible crystals or cleavage. Hardness is approximately 6.5–7 Mohs; specific gravity about 2.6.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic ash, sediments, or other rock, with iron oxides producing the brown coloration. Its exact geological age cannot be determined from the photograph.
Uses & applications
Commonly cut and polished for cabochons, beads, carvings, and decorative objects; attractive tumbled pieces generally have modest value.
Geological facts
Jasper is a variety of opaque chalcedony and is often grouped with microcrystalline quartz. The specimen appears human-tumbled and polished rather than naturally weathered.
Field identification & locations
Identify it by its opaque appearance, earthy iron-rich color, glassy/waxy polish, and ability to scratch ordinary glass; a streak test should be white to colorless. Similar material may be found worldwide, especially in volcanic and sedimentary terrains.
