sedimentary

Jasper or Banded Chert

Silicon dioxide (SiO2) with impurities

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: Variegated brown, grey, and cream bands, Luster: Dull to waxy, Crystal Structure: Microcrystalline (trigonal), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.58-2.91

Hardness: 6

Identified May 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich microfossils or chemical precipitation from sea water, often occurring as nodules in limestone or as distinct bedded deposits. This specimen has been tumbled or polished into an egg shape.

Uses & applications

Used primarily in lapidary work for jewelry, decorative stones, carvings, and as pocket stones for collectors.

Geological facts

Jasper is an opaque variety of chalcedony. The banding seen here often results from variations in oxygen levels or mineral impurities during the deposition process millions of years ago.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife) and its smooth, waxy surface when wet. Commonly found in riverbeds or coastal areas where erosion has exposed silica-rich veins.