Rock Identifier
Polished brown jasper (Jasper (microcrystalline quartz, SiO₂), likely iron-oxide-rich variety) — mineral
mineral

Polished brown jasper

Jasper (microcrystalline quartz, SiO₂), likely iron-oxide-rich variety

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque mustard-brown with darker gray-brown bands or fractures, vitreous to waxy luster, and no visible cleavage. Its rounded, polished form reflects human finishing rather than natural crystal shape.

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Physical properties

Hardness about 6.5–7 Mohs; opaque mustard-brown with darker gray-brown bands or fractures, vitreous to waxy luster, and no visible cleavage. Its rounded, polished form reflects human finishing rather than natural crystal shape.

Formation & geological history

Jasper forms when silica-rich fluids replace or cement sediments, commonly incorporating iron oxides that produce brown, red, or yellow colors; exact age and locality cannot be determined from the image. It occurs in volcanic and sedimentary environments worldwide.

Uses & applications

Used for cabochons, beads, carvings, worry stones, and decorative objects; attractive patterned pieces generally sell for modest amounts.

Geological facts

Jasper is a variety of chalcedony or microcrystalline quartz, although some trade specimens are compositionally mixed. Its opacity and earthy coloration distinguish it from transparent quartz varieties.

Field identification & locations

Identify it by its opaque appearance, smooth polish, quartz-like hardness, and inability to scratch it with a steel knife easily; a streak or hardness test can help confirm it. Common sources include India, Madagascar, Brazil, the United States, and Australia.