sedimentary

Banded jasper (polished/tumbled)

Microcrystalline quartz (SiO₂), commonly iron-oxide– and clay-rich chert

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque reddish-brown, tan, cream, and gray bands; dull to slightly waxy luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The layered appearance may also indicate silicified sediment or brecciated jasper.

Identified September 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement fine sediment, with iron oxides producing red-brown coloration; banding reflects changing sediment chemistry or repeated silica deposition. Usually Precambrian to younger, depending on locality.

Uses & applications

Used for cabochons, carvings, beads, bookends, and ornamental stone; durable but not typically fine-jewelry grade.

Geological facts

Jasper is an opaque variety of chert and can preserve sedimentary textures or fossil-like patterns. Its colors commonly arise from hematite and goethite inclusions.

Field identification & locations

Identify by its opaque body, strong fine banding, waxy polish, and quartz-like hardness; it should scratch glass but not be scratched by a steel blade. Common sources include Oregon, Utah, Idaho, Madagascar, India, and Australia.