sedimentary
Chert / Flint
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: typically dark gray, black, or brown (flint variety); Luster: waxy or dull; Crystal structure: cryptocrystalline; Cleavage: none, exhibits strong conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Color
- typically dark gray, black, or brown (flint variety)
- Luster
- waxy or dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically dark gray, black, or brown (flint variety); Luster: waxy or dull; Crystal structure: cryptocrystalline; Cleavage: none, exhibits strong conchoidal fracture.
Formation & geological history
Formed through the accumulation of silica-rich organic remains (like radiolaria or diatoms) or chemical precipitation from groundwater within sedimentary host rocks like limestone or chalk.
Uses & applications
Historically used for stone tools and fire-starting; currently used for road surfacing, grinding media, and occasionally in jewelry as a gemstone.
Geological facts
Flint was one of the most important resources for prehistoric humans because it breaks into very sharp edges that could be used for arrowheads and knives.
Field identification & locations
Identify by its waxy luster, extreme hardness (scratches glass), and shell-like (conchoidal) curves on broken surfaces. Often found as nodules within chalk or limestone formations.
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