sedimentary
Chert (Flint)
SiO2 (Microcrystalline Quartz)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale. Color: Dark gray to brown and black with sharp edges. Luster: Waxy to vitreous. Fracture: Conchoidal. Specific Gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Dark gray to brown and black with sharp edges
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7 on Mohs scale. Color: Dark gray to brown and black with sharp edges. Luster: Waxy to vitreous. Fracture: Conchoidal. Specific Gravity: 2.65.
Formation & geological history
Formed in marine or freshwater environments by the precipitation of silica from seawater or hydrothermal fluids, often accumulating as nodules in limestone or chalk beds.
Uses & applications
Historically used for making stone tools, arrowheads, and spark-striking flints. Modern uses include gravel aggregate, decorative stone, and lapidary work.
Geological facts
Flint was essential to early human survival as it breaks with extremely sharp edges (conchoidal fracture) perfect for knapping knives, scrapers, and arrowheads.
Field identification & locations
Identified by its glass-like sharp edges when broken, waxy surface texture, and ability to scratch glass easily. Commonly found in limestone outcrops, river beds, and coastal chalk deposits.
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