sedimentary
Chert
Channery Chert (Microcrystalline Quartz)
Hardness: 7 Mohs scale; Color: Tan, brown, gray; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 Mohs scale
- Color
- Tan, brown, gray
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 Mohs scale; Color: Tan, brown, gray; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed by the precipitation of silica from groundwater or within biological sedimentary deposits, typically in marine environments during the Cenozoic or Mesozoic eras.
Uses & applications
Historically used for stone tools and arrowheads; currently used in construction aggregate and as a collector's specimen.
Geological facts
Chert has a unique property where it can produce sparks when struck against steel. It is fundamentally the same material as flint, but the term 'flint' is usually reserved for dark specimens found in chalk.
Field identification & locations
Identify by its very high hardness (scratches glass) and smooth, shell-like fracture surfaces. Often found in limestone or dolomite beds.
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