sedimentary
Chert (Flint)
Chert (SiO2)
Hardness: 7 on Mohs scale; Color: Gray, black, brown, or white; Luster: Waxy to dull; Crystal structure: Microcrystalline/cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Gray, black, brown, or white
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Gray, black, brown, or white; Luster: Waxy to dull; Crystal structure: Microcrystalline/cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Often found as nodules in limestone or chalk beds.
Uses & applications
Historically used for making stone tools (arrowheads, scrapers) and primitive fire-starting. Currently used in road construction, landscape gravel, and occasionally for historical replicas.
Geological facts
Flint was one of the most important minerals for early human technological development due to its ability to produce sharp edges and sparks.
Field identification & locations
Identify by its characteristic conchoidal (shell-like) fracture, extreme hardness (it will scratch glass), and waxy appearance. Commonly found in riverbeds or chalk cliffs.
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