sedimentary

Chert (Flint Pebbles)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

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

Identified June 2, 2026More sedimentary →

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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.