
metamorphic
Polished jasper pebble
Jasper, microcrystalline quartz (SiO₂) with iron-oxide impurities
AI-generated identification · may be incorrectOpaque reddish-brown stone with cream-colored vein-like patterns and a smooth, waxy-to-dull luster; quartz hardness about 6.5–7 Mohs, no visible cleavage, cryptocrystalline structure, and specific gravity around 2.6.…
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Physical properties
Opaque reddish-brown stone with cream-colored vein-like patterns and a smooth, waxy-to-dull luster; quartz hardness about 6.5–7 Mohs, no visible cleavage, cryptocrystalline structure, and specific gravity around 2.6. The pattern may represent brecciation or mineral-filled fractures, possibly resembling brecciated jasper or mookaite-like jasper.
Formation & geological history
Forms when silica-rich fluids cement or replace volcanic or sedimentary material, with iron oxides producing the red-brown color; formation ages vary widely from Precambrian to younger. The rounded shape indicates water abrasion, followed by polishing or natural smoothing.
Uses & applications
Used for cabochons, beads, carvings, ornamental stone, and small decorative objects; too small and patterned for typical construction use.
Geological facts
Jasper is an opaque variety of chalcedony/microcrystalline quartz rather than a single mineral species. Its contrasting veins commonly arise from silica, quartz, calcite, or iron-oxide-filled fractures.
Field identification & locations
Identify by its opacity, red-brown coloration, very fine texture, and inability to scratch with a steel knife easily; it should not fizz in dilute hydrochloric acid unless carbonate-filled veins are present. Common in volcanic terrains and gravel deposits worldwide.
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