mineral
Tumbled brown jasper
Microcrystalline quartz/chalcedony (SiO₂), iron-oxide colored
AI-generated identification · may be incorrectOpaque reddish-brown, smooth rounded surface, earthy to slightly waxy luster, and typically no visible crystals or cleavage. Hardness is about 6.5–7 Mohs; specific gravity is approximately 2.55–2.70.
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Physical properties
Opaque reddish-brown, smooth rounded surface, earthy to slightly waxy luster, and typically no visible crystals or cleavage. Hardness is about 6.5–7 Mohs; specific gravity is approximately 2.55–2.70.
Formation & geological history
Jasper forms when silica-rich groundwater fills and replaces sediment or volcanic material, incorporating iron oxides that produce the brown-red color. Most examples are Cenozoic to Precambrian in age, depending on locality.
Uses & applications
Used for cabochons, beads, carvings, polished stones, and decorative objects; lower-grade pieces are common lapidary material. It has modest collector value.
Geological facts
Jasper is an opaque variety of chalcedony or microcrystalline quartz rather than a single mineral species. Brown coloration commonly results from hematite or goethite inclusions.
Field identification & locations
Identify it by its opacity, fine grain, earthy red-brown color, lack of cleavage, and ability to scratch glass; a steel file usually does not scratch it easily. Common sources include India, Madagascar, Brazil, Australia, and the western United States.
