sedimentary
Chert / Flint Nodule
Silicon Dioxide (SiO2)
Hardness: 7; Color: Cream, tan, or gray; Luster: Dull/Waxy; Structure: Microcrystalline; Cleavage: None (Conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7
- Color
- Cream, tan, or gray
- Luster
- Dull/Waxy
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Physical properties
Hardness: 7; Color: Cream, tan, or gray; Luster: Dull/Waxy; Structure: Microcrystalline; Cleavage: None (Conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich fluids in sedimentary layers, primarily limestone or chalk, often as a result of chemical precipitation or biological remains like radiolarians or diatoms during the Cretaceous period.
Uses & applications
Historically used for stone tools and starting fires; currently used in construction aggregate and as a collector's specimen.
Geological facts
Flint was the primary material for tool-making for hundreds of thousands of years. This specimen shows a characteristic chalky cortex covering the inner microcrystalline silica.
Field identification & locations
Identify by its waxy texture when broken and its ability to scratch glass. Commonly found in chalk deposits or as rounded pebbles on beaches.
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