mineral

Tumbled jasper or iron-rich chert

Microcrystalline quartz (SiO₂), likely with iron-oxide inclusions

AI-generated identification · may be incorrect

Opaque, rounded, brown-gray to reddish specimen with subdued waxy luster; quartz hardness about 6.5–7 Mohs, no visible cleavage, and conchoidal fracture. The mottled dark areas may be hematite, goethite, or other iron oxides; exact identification requires testing.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or fills cavities in sedimentary rocks, with iron minerals creating the red-brown coloration; commonly Cenozoic to older, but age is locality-dependent. Its smooth shape indicates natural abrasion or tumbling.

Uses & applications

Used as a low-cost lapidary stone for cabochons, beads, carvings, and decorative tumbled specimens; not generally used structurally.

Geological facts

Jasper is a variety of opaque chalcedony or microcrystalline quartz, while chert is a broader silica-rich rock category. A streak test, hardness test, and magnification would help distinguish them.

Field identification & locations

Common in gravel beds and volcanic or sedimentary terrains, especially in the western United States, Australia, Brazil, and Africa. It should scratch glass but not be scratched by a steel knife; avoid destructive testing if valuable.