sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
Hardness: 7; Color: Gray, brown, tan; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7
- Color
- Gray, brown, tan
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7; Color: Gray, brown, tan; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich microfossils or chemical precipitation in sedimentary basins. Often found as nodules within limestone or chalk beds.
Uses & applications
Historical tool-making (arrowheads, scrapers), primitive fire starting, construction aggregate, and lapidary use for tumbling or polishing.
Geological facts
Flint is a variety of chert that was essential to human survival for millennia due to its ability to produce sharp edges and sparks. It's often associated with the Stone Age.
Field identification & locations
Identify by its waxy texture and sharp, shell-like (conchoidal) fractures. Found in riverbeds, limestone quarries, and coastal chalk cliffs.
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