sedimentary

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Tan, beige, or brown; Luster: Dull to waxy; Crystal Structure: Cryptocrystalline (microscopic quartz); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6

Hardness: 7 on Mohs scale
Color: Tan, beige, or brown
Luster: Dull to waxy

Identified June 21, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Tan, beige, or brown; Luster: Dull to waxy; Crystal Structure: Cryptocrystalline (microscopic quartz); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolaria) or via chemical precipitation in marine or groundwater environments. Found in sedimentary layers like limestone or chalk.

Uses & applications

Historically used for stone tools and arrowheads. Currently used in road surfacing, decorative landscaping, and occasionally as a gemstone (Jasper varieties).

Geological facts

Because of its conchoidal fracture, it breaks with sharp edges, making it a primary material for prehistoric 'flint-knapping.' It is incredibly durable and chemically stable.

Field identification & locations

Identify by its extreme hardness (scratches glass), smooth waxy feel on breaks, and 'shell-like' curved fracture patterns. Commonly found in riverbeds or as nodules in limestone outcrops.