sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7. Color: dark brown to black. Luster: waxy to vitreous. Structure: cryptocrystalline. Known for conchoidal fracture and sharp edges.
- Hardness
- 6
- Color
- dark brown to black
- Luster
- waxy to vitreous
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Physical properties
Hardness: 6.5-7. Color: dark brown to black. Luster: waxy to vitreous. Structure: cryptocrystalline. Known for conchoidal fracture and sharp edges.
Formation & geological history
Formed through the accumulation of siliceous remains of marine organisms or the precipitation of silica from groundwater within limestone or chalk beds. Commonly formed in the Paleozoic to Mesozoic eras.
Uses & applications
Historically used for stone tools and weapons (arrowheads). Today used as aquarium gravel, in road construction, and for fire-starting tools (flint and steel).
Geological facts
Flint is the most common variety of chert. When struck against steel, it produces sparks, which led to its widespread use in early firearms like flintlocks.
Field identification & locations
Identify by its waxy appearance and shell-like (conchoidal) breakage pattern. Found globally in sedimentary basins, often as nodules inside limestone cliffs or as rounded river/beach pebbles.
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