sedimentary
Banded Flint / Chert
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Dark grey to charcoal with light bands; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6
- Hardness
- 6
- Color
- Dark grey to charcoal with light bands
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Dark grey to charcoal with light bands; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6
Formation & geological history
Formed in marine sedimentary environments through the accumulation of siliceous remains of organisms or chemical precipitation. These specific bands indicate rhythmic deposition or pressure-induced mineral migration.
Uses & applications
Historical tool-making (arrowheads), modern landscaping, fire-starting flint, and semi-precious tumbled stones for jewelry.
Geological facts
Flint was one of the first materials used by early humans for tools because of its ability to fracture into extremely sharp edges. It is often found in chalk or limestone deposits.
Field identification & locations
Identify by its characteristic waxy surface and conchoidal (shell-like) fracture edges. Found globally in coastal areas and riverbeds with sedimentary erosion.
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