sedimentary
Flint
Silicon dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Brown, gray, or black; Luster: Waxy to vitreous; Crystal structure: Microcrystalline quartz (chalcedony); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.60-2.65
- Hardness
- 7 on Mohs scale
- Color
- Brown, gray, or black
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Brown, gray, or black; Luster: Waxy to vitreous; Crystal structure: Microcrystalline quartz (chalcedony); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.60-2.65
Formation & geological history
Forms by the replacement of calcium carbonate by silica-rich solutions in chalk or limestone formations during the Cretaceous period or other sedimentary environments.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used in abrasives, ceramics, and ornamental landscaping.
Geological facts
Flint was one of the earliest materials manipulated by early humans to create sophisticated tools and weapons due to its predictable conchoidal fracture.
Field identification & locations
Identified easily by its conchoidal fracture edges and ability to produce sparks when struck with steel. Commonly found in chalk deposits and gravel beds worldwide.
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