sedimentary

Tumbled banded stone, likely jasper or chert

Microcrystalline quartz (SiO₂), probably banded jasper/chert

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque gray-brown with dark reddish-brown bands, a smooth tumbled surface, and dull to waxy luster. Quartz is cryptocrystalline, with no visible cleavage and conchoidal fracture.

Identified August 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed from silica-rich sediment that replaced or cemented earlier material, with iron or manganese producing the darker bands; commonly Paleozoic to Cenozoic, though age cannot be determined from the photograph.

Uses & applications

Used as a lapidary stone for cabochons, carvings, polished pebbles, and collectibles; generally not used structurally.

Geological facts

The specimen’s rounded shape and uniform polish indicate human tumbling. Distinguishing jasper from chert usually requires texture, translucency, and locality information.

Field identification & locations

Identify by its very hard, fine-grained, opaque quartz texture and conchoidal fracture; common sources include sedimentary formations worldwide, especially India, Madagascar, Brazil, and the western United States.