metamorphic

Polished brecciated jasper

Microcrystalline quartz (SiO₂), commonly with iron oxides and altered volcanic fragments

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown, tan, black, and reddish bands with a waxy-to-glassy polish. Cryptocrystalline quartz has no visible cleavage, conchoidal fracture, and typical specific gravity near 2.6.

Identified September 14, 2026More metamorphic →

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Physical properties

Formation & geological history

Jasper forms when silica-rich fluids replace or cement volcanic and sedimentary material; the mottled pattern likely reflects brecciation and iron staining. Formation ages vary widely, commonly Precambrian to younger, depending on locality.

Uses & applications

Used for cabochons, beads, carvings, tumbling, and ornamental objects; rarely used as a minor decorative stone in architecture.

Geological facts

Its patterns are produced by iron oxides and included rock fragments rather than distinct large crystals. The specimen appears shaped and highly polished, so natural surface texture and field tests are obscured.

Field identification & locations

Identify by its opaque patterned body, quartz-like hardness, lack of cleavage, and resistance to scratching by a steel knife; glass scratch testing is more diagnostic. Common sources include Australia, Madagascar, India, Brazil, and the western United States.