sedimentary
Chert
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7; Color: various, often pale, brown, gray, or banded; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none, conchoidal fracture
- Hardness
- 6
- Color
- various, often pale, brown, gray, or banded
- Luster
- waxy to dull
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Physical properties
Hardness: 6.5-7; Color: various, often pale, brown, gray, or banded; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none, conchoidal fracture
Formation & geological history
Forms as a chemical precipitate or from the accumulation of silica-rich biological remains (like diatoms or radiolarians) in marine environments.
Uses & applications
Historically used for making stone tools and fire-starting (flint). Occasionally used as a semi-precious stone if attractively banded.
Geological facts
Flint is a specific type of chert found in chalk or marly limestone. The piece shown appears to have been worked or struck, showing conchoidal fractures typical of knapping.
Field identification & locations
Identified by its hardness (scratches glass), waxy luster, and conchoidal fracture. Found worldwide in sedimentary rock sequences.
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