sedimentary

Banded chert or jasper pebble

Microcrystalline quartz (SiO₂), likely chert/jasper with iron-oxide staining

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, tan, cream, and gray bands with a dull to waxy luster. It is very fine-grained and non-cleaving, with conchoidal fracture; visible layering may reflect silica-rich sediment or chalcedony veins.

Identified September 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when silica-rich fluids or biogenic silica replaced or cemented sediment, with iron oxides producing the brown coloration; banding developed during repeated deposition or alteration. The specimen is likely a weathered river or beach cobble, with age dependent on its source formation.

Uses & applications

Used as an ornamental stone, cabochon, bead, carving material, and occasional toolstone; generally unsuitable for major construction aggregate because of its small size.

Geological facts

Chert and jasper are varieties of microcrystalline quartz; jasper is typically opaque and impurity-rich, while chert may be more uniformly gray or translucent. The pale bands could also represent chalcedony-filled fractures.

Field identification & locations

Identify by its very hard, dense body, glassy or waxy fracture, and inability to scratch with a steel knife; it should scratch ordinary glass. Common sources include sedimentary terrains and gravel bars worldwide.