sedimentary

Chert (Flint variety)

Chert (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Grey, tan, or brown with waxy luster; Crystal Structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 7 on Mohs scale
Color: Grey, tan, or brown with waxy luster

Identified April 8, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Grey, tan, or brown with waxy luster; Crystal Structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or through the chemical precipitation of silica in groundwater. Found in marine or lacustrine sedimentary layers.

Uses & applications

Historically used for stone tools (arrowheads, scrapers); currently used as an abrasive, in road construction, and for decorative landscaping.

Geological facts

Chert was one of the most important minerals for early humans because its conchoidal fracture creates extremely sharp edges; it was also used in early firearms as 'flint' to create sparks.

Field identification & locations

Identify by its 'flint-like' appearance, waxy texture on broken surfaces, and inability to be scratched by a steel knife. It will also spark when struck against steel. Found globally in limestone formations.