mineral
Tumbled jasper (likely orbicular or brecciated jasper)
Jasper, microcrystalline quartz (SiO₂) with iron-oxide inclusions
AI-generated identification · may be incorrectOpaque brown-gray pebble with mustard-yellow and reddish inclusions, matte-to-waxy luster, and rounded polish. Quartz hardness is about 6.5–7 Mohs; no visible cleavage, cryptocrystalline structure, and specific gravity near 2.6.
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Physical properties
Opaque brown-gray pebble with mustard-yellow and reddish inclusions, matte-to-waxy luster, and rounded polish. Quartz hardness is about 6.5–7 Mohs; no visible cleavage, cryptocrystalline structure, and specific gravity near 2.6.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic ash, sediments, or breccia, with iron oxides creating the yellow-brown coloration. Its exact geological age and locality cannot be determined from the photograph.
Uses & applications
Commonly used for tumbled stones, cabochons, carvings, beads, and decorative objects; occasionally used as low-cost ornamental stone.
Geological facts
The pattern likely reflects iron-oxide minerals such as goethite or hematite dispersed through microcrystalline quartz. Jasper varieties are named mainly by color, pattern, and locality rather than by distinct chemical composition.
Field identification & locations
Identify it by its opaque appearance, earthy multicolor pattern, glassy-to-waxy polish, and resistance to scratching by a steel knife; it should not fizz in dilute acid. Common sources include India, Madagascar, Brazil, Australia, and the western United States.
