mineral
Tumbled brown jasper
Jasper, microcrystalline quartz (SiO₂), commonly colored by iron oxides
AI-generated identification · may be incorrectOpaque reddish-brown to chocolate brown, waxy-to-dull luster, massive cryptocrystalline structure, no visible cleavage; Mohs hardness about 6.5–7 and specific gravity approximately 2.6.
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Physical properties
Opaque reddish-brown to chocolate brown, waxy-to-dull luster, massive cryptocrystalline structure, no visible cleavage; Mohs hardness about 6.5–7 and specific gravity approximately 2.6.
Formation & geological history
Jasper forms when silica-rich groundwater replaces or fills volcanic ash, sediments, or cavities, with iron producing the brown-red color. The specimen’s precise geological age cannot be determined from the image.
Uses & applications
Used for carvings, cabochons, beads, ornaments, and decorative objects; durable pieces are popular as inexpensive lapidary material and collectibles.
Geological facts
Jasper is a variety of chalcedony/microcrystalline quartz, though its abundant impurities make it opaque. Brown varieties may be marketed as picture jasper, mookaite, or brecciated jasper depending on pattern and locality.
Field identification & locations
Identify it by its opaque earthy color, smooth waxy fracture, lack of cleavage, and ability to scratch glass; it commonly occurs in volcanic and sedimentary terrains worldwide, including India, Madagascar, Brazil, Australia, and the western United States.
