sedimentary
Chert (Flint)
Cryptocrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 7.0, Color: tan, brown, or grey with waxy luster. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.
- Hardness
- 7
- Color
- tan, brown, or grey with waxy luster
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Physical properties
Hardness: 7.0, Color: tan, brown, or grey with waxy luster. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.
Formation & geological history
Formed in sedimentary environments from the accumulation of silica-rich organic remains (like diatoms or radiolarians) or chemical precipitation from groundwater.
Uses & applications
Historically used for stone tools and fire-starting. Currently used in road surfacing, as grinding media, and occasionally as decorative landscaping stone.
Geological facts
Flint is a variety of chert that produced sparks when struck against steel, making it essential for early firearms like flintlocks. It breaks with extremely sharp edges, sharper than a surgeon's scalpel.
Field identification & locations
Identify by its smooth, waxy surface and characteristic shell-like (conchoidal) fractures. Found globally in limestone and chalk beds, particularly in the UK, USA, and France.
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