mineral

Tumbled brown jasper (probable ocean jasper or iron-rich chert)

Microcrystalline quartz, SiO₂, with iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown to reddish-brown, earthy colors, smooth polish, and dull to waxy luster. Composed of cryptocrystalline quartz with scattered dark iron-oxide or manganese-rich spots; no visible cleavage, conchoidal fracture possible, specific gravity about 2.6.

Identified September 4, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement sediment, often with iron-oxide impurities producing the brown color and orbicular spots. Precise age and locality cannot be determined from the photograph; similar jasper forms in volcanic and sedimentary terrains worldwide.

Uses & applications

Used as tumbled stone, cabochons, carvings, beads, and decorative objects; occasionally used as aggregate or ornamental facing.

Geological facts

Jasper is a variety of chert distinguished mainly by its opacity and abundant impurities. The specimen appears shaped and polished, so its natural textures and original surface are partly obscured.

Field identification & locations

Identify by its very fine grain, opaque body, glass-scratching hardness, and lack of cleavage; it should not fizz in dilute acid. Common sources include Madagascar, Brazil, India, Australia, and the western United States.