sedimentary
Chert (Arrowhead Fragment)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs; Color: Tan to light brown with iron staining; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 6
- Color
- Tan to light brown with iron staining
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Tan to light brown with iron staining; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed as nodules in limestone or chalk through the accumulation of silica-rich organic remains (like diatoms or radiolarians). This specific piece shows evidence of anthropogenic shaping (knapping) into a projectile point fragment.
Uses & applications
Historically used for stone tools and weapons due to its sharp conchoidal fracture. Currently valued as an archaeological artifact or for lithic study.
Geological facts
Chert has been used by humans for millions of years. When struck, it breaks into scales with razor-sharp edges. This piece appears to be a bifacially worked fragment, likely a projectile tip or scraper.
Field identification & locations
Identify by looking for 'bulb of percussion' or flake scars from knapping. Commonly found in creek beds or fields where sedimentary layers have eroded, especially in areas with known historical indigenous activity.
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