sedimentary

Chert (or Jasper)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 Mohs scale; Color: Brown, tan, reddish; Luster: Waxy to dull; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 Mohs scale
Color: Brown, tan, reddish
Luster: Waxy to dull

Identified June 18, 2026More sedimentary →

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Physical properties

Hardness: 7 Mohs scale; Color: Brown, tan, reddish; Luster: Waxy to dull; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed by the precipitation of silica in marine environments or through the replacement of limestone by silica-rich fluids. Can be found in many geological formations globally.

Uses & applications

Historically used for making stone tools (arrowheads). Today used as aquarium gravel, landscaping stone, and occasionally for lapidary work if it has attractive banding.

Geological facts

Because it is harder than steel and breaks with sharp edges, it was one of the most important minerals for early humans to create survival tools.

Field identification & locations

Identify by its extreme hardness (cannot be scratched by steel) and smooth, curved conchoidal fractures. Commonly found in stream beds or as nodules in limestone.