mineral

Polished/tumbled brown jasper or iron-rich chert

Microcrystalline quartz (SiO₂), commonly colored by hematite/goethite

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque reddish-brown to dark brown with glassy/waxy luster and no visible cleavage. Dense, fine-grained cryptocrystalline quartz; the smooth surface appears polished or naturally water-worn.

Identified August 10, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement sediments, with iron oxides producing the brown-red color; commonly Precambrian to much younger. This specimen has been human-polished or heavily rounded by abrasion.

Uses & applications

Used for cabochons, beads, carvings, worry stones, and decorative objects; valued more for appearance than industrial use. Common material is inexpensive.

Geological facts

Jasper is an opaque variety of chalcedony/chert, while iron-rich varieties may grade into brecciated jasper or ironstone. Surface highlights and rounded edges strongly suggest a polished tumbled specimen.

Field identification & locations

Identify by its uniform fine texture, lack of cleavage, high hardness, and inability to scratch with a steel knife easily; quartz glass or a streak test can help, though coatings may interfere. Common in many regions, including the western United States, Brazil, India, Madagascar, and Australia.