mineral

Polished brecciated jasper

Jasper, microcrystalline quartz (SiO₂), with iron-oxide and dark matrix inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown, ochre, black, and gray; vitreous to waxy luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The rounded shape and glossy surface indicate tumbling or natural water abrasion.

Identified September 14, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or cements volcanic ash, sediment, or rock fragments, with iron oxides producing the brown-red colors. Deposits commonly range from Precambrian to Cenozoic in age.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and lapidary specimens; occasionally as decorative aggregate. Common polished pieces generally have modest value.

Geological facts

Jasper is a variety of opaque chalcedony and can display brecciated, orbicular, or picture-like patterns. Its colors are chiefly controlled by hematite, goethite, magnetite, and other inclusions.

Field identification & locations

Identify it by its opaque patterned body, quartz-like hardness, lack of cleavage, and inability to scratch with a steel knife easily; a streak test is usually white to brown. Found worldwide, notably in India, Madagascar, Brazil, Australia, and the western United States.