sedimentary
Chert / Flint
Microcrystalline Quartz (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-brown to dark brown; Luster: Waxy to sub-vitreous; Fracture: Conchoidal; Specific Gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Grayish-brown to dark brown
- Luster
- Waxy to sub-vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-brown to dark brown; Luster: Waxy to sub-vitreous; Fracture: Conchoidal; Specific Gravity: 2.65.
Formation & geological history
Formed through the accumulation of siliceous remains of microscopic organisms (diatoms, radiolarians) or chemical precipitation of silica in marine sedimentary environments.
Uses & applications
Historically used for stone tools, flintknapping, arrowheads, and spark generation. Modern uses include gravel, road aggregate, and lapidary art.
Geological facts
Flint is a variety of chert that produces sparks when struck against steel, making it vital for early human survival and early firearm mechanisms.
Field identification & locations
Identified by its smooth, waxy surface, extreme hardness, and sharp conchoidal edges when fractured. Commonly found in limestone, chalk beds, and river beds globally.
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