sedimentary

Tumbled jasper, likely ocean or brecciated jasper

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

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque, cream, brown, gray, and reddish mottling; dull to waxy luster; cryptocrystalline quartz with no visible cleavage; specific gravity about 2.5–2.7. The rounded surface indicates natural water-worn or mechanically tumbled material.

Identified August 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Jasper forms when silica-rich fluids replace or cement volcanic ash, sediment, or breccia, commonly with iron staining; ages vary widely from Precambrian to Cenozoic. This specimen’s exact locality and age cannot be determined from the photograph.

Uses & applications

Used as low-cost cabochons, beads, carvings, polished stones, and decorative aggregate; valued mainly for pattern and polish rather than rarity.

Geological facts

Jasper is a variety of opaque chalcedony, often grouped with quartz-rich cherts. Distinctive orbicular or brecciated patterns can increase desirability.

Field identification & locations

Identify by its opacity, waxy polish, quartz-like hardness, and colorful irregular pattern; it should resist scratching by steel but scratch glass. Common sources include Oregon, Idaho, California, Madagascar, Australia, and Brazil.