mineral

Tumbled brown chalcedony or jasper

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque to slightly translucent reddish-brown, with a smooth polished surface and waxy to vitreous luster. Quartz has a trigonal crystal structure but is microcrystalline here, with no visible cleavage and conchoidal fracture.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich groundwater filled cavities or replaced host rock, with iron oxides producing the brown-red color; age varies widely by deposit. Its rounded shape is human-produced by tumbling and polishing.

Uses & applications

Used as an inexpensive lapidary stone for cabochons, beads, carvings, and decorative objects; suitable for jewelry but less valuable than gem-grade varieties.

Geological facts

The specimen may be called brown jasper if fully opaque or brown chalcedony if translucent. Surface color and pattern can be enhanced by polishing or dyeing.

Field identification & locations

Identify by its glassy/waxy luster, very fine texture, lack of cleavage, and ability to scratch ordinary glass; avoid relying on color alone because dyed stone and glass imitations are common. Similar material occurs worldwide, including Brazil, India, Madagascar, Uruguay, and the United States.