sedimentary

Polished brecciated jasper

Silicified microcrystalline quartz (chalcedony), commonly called jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque cream, tan, gray, and reddish-brown patches with a waxy to vitreous polish. Massive, cryptocrystalline quartz; no visible cleavage, conchoidal fracture, specific gravity roughly 2.5–2.7.

Identified August 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when silica-rich fluids replaced or cemented fragmented volcanic or sedimentary material, producing brecciation and multicolored patterns; typically Cenozoic to older, depending on locality.

Uses & applications

Used for lapidary cabochons, tumbled stones, beads, carvings, and decorative objects; rarely used as a minor aggregate or ornamental stone.

Geological facts

Jasper is an opaque variety of chalcedony distinguished from agate by its low translucency. The irregular cream-and-gray pattern suggests breccia or replacement textures rather than a single uniform mineral.

Field identification & locations

Identify it by its opaque, fine-grained appearance, quartz-like hardness, lack of cleavage, and ability to take a high polish; a steel file should not easily scratch it. Common sources include Oregon, Idaho, Utah, California, Mexico, Madagascar, and Australia; exact locality requires matrix or provenance.