mineral
Tumbled jasper (likely brecciated or common jasper)
Jasper, opaque microcrystalline quartz (SiO₂) with iron-oxide impurities
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; reddish-brown to tan, opaque, with a dull to waxy luster and irregular pale quartz/chalcedony patches. Dense and compact, with no visible cleavage; specific gravity about 2.55–2.70.
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Physical properties
Hardness 6.5–7 Mohs; reddish-brown to tan, opaque, with a dull to waxy luster and irregular pale quartz/chalcedony patches. Dense and compact, with no visible cleavage; specific gravity about 2.55–2.70.
Formation & geological history
Forms when silica-rich groundwater replaces or cements sediments and volcanic material, with iron oxides producing the red-brown color. Jasper deposits range from Precambrian to recent; this specimen has been shaped and polished by tumbling.
Uses & applications
Used for cabochons, beads, carvings, decorative stone, and lapidary collections; occasionally used as a low-cost ornamental aggregate.
Geological facts
Jasper is a variety of chalcedony or microcrystalline quartz, though the term is often used broadly for opaque silica-rich rocks. Its patterns and colors commonly reflect iron, manganese, clay, or incorporated rock fragments.
Field identification & locations
Identify it by its opaque body, earthy red-brown color, fine texture, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include India, Madagascar, Brazil, Australia, Mexico, and the western United States.
