mineral

Tumbled 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 with black and mustard-yellow patches, waxy to glossy luster, and no visible cleavage. The rounded shape indicates mechanical tumbling or natural abrasion.

Identified September 3, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement sediment, with iron oxides producing the brown, red, and yellow colors; commonly Precambrian to younger, depending on the source formation.

Uses & applications

Used as an inexpensive lapidary stone for cabochons, beads, carvings, and polished collectibles; typically valued for pattern and color rather than rarity.

Geological facts

The specimen appears most consistent with brecciated or inclusion-rich jasper, though a photograph cannot distinguish it confidently from iron-stained chert or brown agate.

Field identification & locations

Identify by its very hard, glass-scratching surface, opaque quartz-rich body, and iron-oxide coloration; common sources include India, Madagascar, Brazil, Australia, and the western United States. Avoid confusing it with softer resin or slag.