sedimentary
Chert (specifically Flint)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, brown, and white; Luster: Waxy to dull; Crystal structure: Cryptocrystalline (microscopic quartz); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, and white
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brown, and white; Luster: Waxy to dull; Crystal structure: Cryptocrystalline (microscopic quartz); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
Formation & geological history
Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or by chemical precipitation in marine environments. This specimen likely originates from limestone or chalk beds and has been smoothed by water transport.
Uses & applications
Historically used for stone tools and starting fires; currently used in construction aggregate, road surfacing, and as a decorative stone in landscaping.
Geological facts
Flint was the primary material for the Stone Age 'industry' because it breaks with sharp edges. It is extremely resistant to chemical weathering.
Field identification & locations
Identify by its waxy texture and shell-like (conchoidal) fractures. Often found in riverbeds or coastal areas where limestone has weathered away. Collectors look for unique banding or color patterns.
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