sedimentary

Chert (Jasper variety)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Brownish-red to dark grey; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 6
Color: Brownish-red to dark grey
Luster: Waxy to dull

Identified June 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich microfossils or chemical precipitation from silica-rich fluids in sedimentary basins. Many specimens date from the Precambrian to Cenozoic eras.

Uses & applications

Commonly used as a decorative stone in landscaping, for making stone tools (historically), and occasionally as a gemstone in jewelry when it exhibits vibrant colors or patterns.

Geological facts

Chert was one of the most important materials for early humans due to its ability to split into sharp edges. Red and brown varieties are often referred to as Jasper.

Field identification & locations

Identify in the field by its smooth, waxy surface and its distinct conchoidal (shell-like) fracture pattern. It will easily scratch glass and does not react with acid.