Sedimentary
Chert
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7, Color: Yellowish-brown to whitish, Luster: Waxy to dull, Crystal structure: Microcrystalline quartz, Cleavage: None (conchoidal fracture).
- Hardness
- 6
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Physical properties
Hardness: 6.5-7, Color: Yellowish-brown to whitish, Luster: Waxy to dull, Crystal structure: Microcrystalline quartz, Cleavage: None (conchoidal fracture).
Formation & geological history
Formed as a chemical sedimentary rock or through biological processes involving silica-rich organisms, often occurring in nodules or beds within limestone or chalk.
Uses & applications
Historically used for making stone tools due to its hardness and conchoidal fracture. Sometimes used as a low-grade gemstone or landscape stone.
Geological facts
Chert that is primarily black or dark gray is often referred to as flint. It was a crucial material for early humans in creating sharp edges for cutting and hunting.
Field identification & locations
Identified by its hardness (scratches glass), smooth but dull or waxy luster, and conchoidal fracture. Often found as rounded nodules in streams or fields.
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