metamorphic
Polished jasper pebble
Jasper, microcrystalline quartz (SiO₂) with iron-oxide and clay-mineral impurities
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque, fine-grained, and typically red, brown, yellow, cream, and gray with a dull to waxy luster. No visible cleavage; conchoidal fracture is expected, though the rounded surface is naturally water-worn or polished.
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Physical properties
Hardness about 6.5–7 Mohs; opaque, fine-grained, and typically red, brown, yellow, cream, and gray with a dull to waxy luster. No visible cleavage; conchoidal fracture is expected, though the rounded surface is naturally water-worn or polished.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic ash, sediments, or altered rock, with iron oxides producing the red-brown colors. Its exact geological age and locality cannot be determined from the image.
Uses & applications
Used as an ornamental stone, cabochon, bead, carving material, and polished display specimen; occasionally used for small decorative objects and lapidary work.
Geological facts
The specimen appears rounded and possibly tumbled or naturally river-worn, with mottled coloration typical of brecciated or impurity-rich jasper. “Picture jasper” is a possible descriptive variety, but the pattern is not diagnostic here.
Field identification & locations
Identify jasper by its opacity, multicolored iron-stained pattern, fine texture, and inability to scratch it with a steel knife easily; quartz-rich jasper can scratch glass. Common sources include volcanic and sedimentary terrains worldwide, including Oregon, California, India, Madagascar, and Brazil.
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