mineral
Polished brown jasper pebble
Jasper, microcrystalline quartz (SiO₂), commonly with iron-oxide impurities
AI-generated identification · may be incorrectOpaque mustard-brown, smoothly polished, with pale vein-like fractures; dull to slightly waxy luster and cryptocrystalline structure. Mohs hardness about 6.5–7; no visible cleavage, specific gravity about 2.6.
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Physical properties
Opaque mustard-brown, smoothly polished, with pale vein-like fractures; dull to slightly waxy luster and cryptocrystalline structure. Mohs hardness about 6.5–7; no visible cleavage, specific gravity about 2.6.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement fine-grained sediments or volcanic material, with iron oxides producing the brown color; its exact geological age cannot be determined from the image. The white lines are likely quartz or calcite-filled fractures.
Uses & applications
Used for beads, cabochons, carvings, ornaments, and tumbled-stone collections; too small and decorative for construction use.
Geological facts
Jasper is technically a variety of chalcedony or microcrystalline quartz, though the term is also used broadly for opaque silica-rich rocks. Color and pattern depend strongly on iron, manganese, and other impurities.
Field identification & locations
Identify by its opaque earthy color, very fine grain, glass-scratching hardness, and lack of fizz in dilute acid; common sources include India, Madagascar, Brazil, Australia, and the western United States. Exact identification would require testing the veins and hardness.
