Rock Identifier
Banded brown jasper (likely picture jasper) (Silicified microcrystalline quartz/chalcedony (SiO₂), commonly iron-oxide stained) — sedimentary
sedimentary

Banded brown jasper (likely picture jasper)

Silicified microcrystalline quartz/chalcedony (SiO₂), commonly iron-oxide stained

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown, tan, and cream banding with a dull to waxy luster. Microcrystalline quartz has no visible cleavage, conchoidal fracture, and typically specific gravity near 2.6.

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Physical properties

Hardness about 6.5–7 Mohs; opaque brown, tan, and cream banding with a dull to waxy luster. Microcrystalline quartz has no visible cleavage, conchoidal fracture, and typically specific gravity near 2.6.

Formation & geological history

Formed when silica-rich groundwater replaced or cemented layered sediment, with iron oxides producing the brown coloration; age depends on the source deposit and cannot be determined from the image. The rounded, polished shape appears human-processed.

Uses & applications

Used for cabochons, carvings, tumbled stones, ornaments, and lapidary display; generally unsuitable as a major construction stone because of its small specimen size.

Geological facts

The flowing bands resemble picture jasper or brown banded jasper, but exact naming requires a fresh surface or locality information. Jasper is an opaque variety of quartz and is often grouped commercially with chalcedony.

Field identification & locations

Commonly found in silica-rich volcanic or sedimentary terrains, including parts of the western United States, Mexico, Madagascar, and Australia. Identify by its opaque fine-grained texture, hardness, lack of fizz in dilute acid, and absence of glassy translucence.