mineral

Tumbled jasper or chert

Microcrystalline quartz (SiO₂), commonly jasper/chalcedony

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque reddish-brown, smooth rounded surface, dull to slightly waxy luster, and no visible cleavage. Its color likely comes from iron oxides; the image alone cannot distinguish jasper from iron-rich chert or another tumbled silicate.

Identified September 5, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or fill sediments and cavities, with iron staining producing red-brown hues; most deposits are Precambrian to Cenozoic. Tumbled shape indicates human abrasion and polishing.

Uses & applications

Used for inexpensive cabochons, beads, carvings, polished stones, and decorative objects; common specimens generally have modest collector value.

Geological facts

Jasper is an opaque variety of chalcedony, while chert is a broader fine-grained silica rock category. A steel file should barely scratch it, and quartz-rich material often produces a white streak rather than a colored one.

Field identification & locations

Common worldwide, including the United States, Mexico, Brazil, Madagascar, India, and Australia. Identify by hardness, opaque silica texture, conchoidal fracture on an unpolished edge, and reddish iron staining; laboratory testing is needed for a precise variety.