sedimentary
Chert (Arrowhead/Projectile Point)
Microcrystalline Quartz (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-brown to tan; Luster: Waxy or dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Grayish-brown to tan
- Luster
- Waxy or dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-brown to tan; Luster: Waxy or dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary basins. The raw material is often millions of years old, though the artifact shape (flaking) was created by human activity during the Holocene.
Uses & applications
Historically used for weaponry and tools (knapping). Today, they are highly valued as archaeological artifacts and collectibles.
Geological facts
This specific piece is a projectile point shaped through 'pressure flaking.' The conchoidal fracture of chert allows it to be worked into an extremely sharp edge, sharper than a modern surgical scalpel in some cases.
Field identification & locations
Identify in the field by looking for distinct flake scars and a notched base indicating hafting. Found globally, especially in areas with limestone deposits. Authentic artifacts should be documented for archaeological context.
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