sedimentary

Chert (Flint variety)

Chert (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs); Color: Tan/Grey; Luster: Dull to waxy; Crystal structure: Microcrystalline (Cryptocrystalline) quartz; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 (Mohs)
Color: Tan/Grey
Luster: Dull to waxy

Identified April 9, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs); Color: Tan/Grey; Luster: Dull to waxy; Crystal structure: Microcrystalline (Cryptocrystalline) quartz; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed from the accumulation of siliceous remains of marine organisms (like diatoms or radiolaria) or by chemical precipitation. This particular specimen appears to be a weathered nodule, possibly from Paleozoic or Mesozoic limestone beds.

Uses & applications

Historically used for stone tools (arrowheads). Modern uses include road surfacing, jewelry (when colorful), and as a raw material in ceramics or glass.

Geological facts

Chert is so hard it can create sparks when struck against steel, leading to its widespread use in flintlock firearms. It was the most important material for early human technology during the Stone Age.

Field identification & locations

Identify by its 'shell-like' conchoidal fracture which leaves sharp edges, its extreme hardness (will scratch glass), and its fine-grained texture. Commonly found in creek beds and limestone outcrops.