sedimentary
Chert (Arrowhead artifact)
Chert (Cryptocrystalline Silica, SiO2)
Hardness: 6.5-7 Mohs; Color: Brown, tan, waxy; Luster: Vitreous to waxy; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 6
- Color
- Brown, tan, waxy
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brown, tan, waxy; Luster: Vitreous to waxy; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed as a chemical precipitate or biochemical deposit in sedimentary rock units, often as nodules in limestone or chalk. This specific specimen has been anthropogenically modified through knapping.
Uses & applications
Historically used for stone tools and weapons (lithics); currently of archaeological, historical, and collecting interest.
Geological facts
Chert and flint were among the first resources used by early humans to create sharp-edged tools due to their predictable conchoidal fracturing patterns.
Field identification & locations
Identify in the field by its waxy texture, hardness (cannot be scratched by steel), and sharp, shell-like fracture edges. Found worldwide in sedimentary basins.
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