sedimentary

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Red-brown to tan; Luster: Dull to waxy; Crystal structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6

Hardness: 6
Color: Red-brown to tan
Luster: Dull to waxy

Identified June 12, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Red-brown to tan; Luster: Dull to waxy; Crystal structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6

Formation & geological history

Formed through the accumulation of silica-rich microfossils or precipitation from silica-rich fluids in sedimentary basins. This specimen likely originates from the Cretaceous or Paleogene sedimentary layers common in the Saratov region of Russia.

Uses & applications

Used historically for stone tools due to its sharp edges when broken; currently used in decorative landscaping, lapidary work, and as a low-cost gemstone.

Geological facts

Chert is extremely durable and chemically stable, making it a common component of river gravels long after softer rocks have eroded away.

Field identification & locations

Identify in the field by its hardness (it can scratch glass and cannot be scratched by a steel knife) and its smooth, shell-like (conchoidal) fracture surfaces. Commonly found in riverbeds and glacial deposits in the Volga Basin.