sedimentary
Chert (Flint Pebbles)
Microcrystalline Quartz (SiO2)
Hardness: 7 Mohs; Color: White, grey, and brown mottled; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
- Hardness
- 7 Mohs
- Color
- White, grey, and brown mottled
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7 Mohs; Color: White, grey, and brown mottled; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine environments; typically Cretaceous in age for many European and coastal deposits.
Uses & applications
Historical toolmaking, modern landscape gravel, road base construction, and mineral collecting.
Geological facts
This specimen appears to be a water-worn flint pebble, commonly found on beaches or in riverbeds. Flint has been a crucial material for humanity since the Stone Age due to its ability to hold a sharp edge.
Field identification & locations
Identify by its 'waxy' texture, extreme hardness (it will scratch glass), and the way it breaks into smooth, bowl-shaped curves known as conchoidal fractures.
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