Rock Identifier
Polished brown jasper (likely brecciated or orbicular jasper) (Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide and other mineral inclusions) — gemstone
gemstone

Polished brown jasper (likely brecciated or orbicular jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide and other mineral inclusions

AI-generated identification · may be incorrect

Typically Mohs 6.5–7; opaque brown, black, cream, and rusty-gold patterning with a glassy-to-waxy polish. It has no visible cleavage and is composed of cryptocrystalline quartz; specific gravity is about 2.6.

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Physical properties

Typically Mohs 6.5–7; opaque brown, black, cream, and rusty-gold patterning with a glassy-to-waxy polish. It has no visible cleavage and is composed of cryptocrystalline quartz; specific gravity is about 2.6.

Formation & geological history

Jasper forms when silica-rich groundwater replaces or cements volcanic ash, sediments, or breccia, commonly with iron-oxide staining. Its exact geological age depends on the deposit, ranging from Precambrian to much younger volcanic or sedimentary settings.

Uses & applications

Used for cabochons, beads, carvings, palm stones, and ornamental objects; polished material is generally decorative rather than industrial.

Geological facts

The specimen’s strongly layered, flowing pattern could also represent polished ribbon jasper or a jasper-rich breccia; a definitive identification requires testing or an unpolished surface.

Field identification & locations

Identify by its opaque body, fine texture, hardness, and inability to scratch with a steel knife easily; common sources include India, Madagascar, Brazil, Mexico, and the western United States. Avoid confusing it with dyed agate or man-made glass.