mineral
Tumbled brown jasper
Microcrystalline quartz (SiO₂), commonly with iron-oxide impurities
AI-generated identification · may be incorrectOpaque mustard-brown to reddish-brown, earthy/waxy luster, no visible crystals, and typically hardness 6.5–7 Mohs; conchoidal fracture is expected, though this specimen is rounded and polished by abrasion. Its density is approximately 2.6 g/cm³.
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Physical properties
Opaque mustard-brown to reddish-brown, earthy/waxy luster, no visible crystals, and typically hardness 6.5–7 Mohs; conchoidal fracture is expected, though this specimen is rounded and polished by abrasion. Its density is approximately 2.6 g/cm³.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic ash, sediment, or fractured rock, with iron oxides producing the brown-red coloration. Formation ages vary widely, from Precambrian to relatively young deposits.
Uses & applications
Used for beads, cabochons, carvings, lapidary objects, and ornamental stone; rarely used as a crushed aggregate. Its value is primarily decorative and collectible.
Geological facts
Jasper is a variety of opaque chalcedony or microcrystalline quartz rather than a distinct mineral species. Brown coloration commonly reflects hematite or limonite.
Field identification & locations
Identify it by its opaque, fine-grained texture, earthy color, glassy-to-waxy polish, and inability to scratch it with a steel knife; quartz or glass can scratch it. Common sources include India, Brazil, Madagascar, the United States, and Australia.
