sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: Brown, gray, or reddish-brown; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline (Cryptocrystalline); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 6
- Color
- Brown, gray, or reddish-brown
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brown, gray, or reddish-brown; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline (Cryptocrystalline); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed as nodules or beds in sedimentary rocks like limestone or chalk when silica rich fluids precipitate out. Common in prehistoric to modern geological layers.
Uses & applications
Historically used for stone tools (arrowheads, scrapers) due to its sharp edges; used in modern times as a source of silica and in construction aggregates.
Geological facts
Flint is a variety of chert. When struck against steel, it creates sparks, which made it essential for early fire-starting and flintlock firearms.
Field identification & locations
Identify by its waxy luster, extreme hardness (scratches glass), and the way it breaks into sharp, curved (conchoidal) flakes. Often found in riverbeds or eroding out of limestone cliffs.
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