sedimentary
Chert (Arrowhead/Projectile Point)
Microcrystalline quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: Brown to tan (coated in red iron-rich soil); Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture)
- Hardness
- 6
- Color
- Brown to tan (coated in red iron-rich soil)
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brown to tan (coated in red iron-rich soil); Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture)
Formation & geological history
Formed as nodules in limestone or chalk through the accumulation of siliceous biological remains. This specimen has been anthropogenically modified (knapped) during the prehistoric era.
Uses & applications
Historically used for tools and weapons; today collected as archaeological artifacts and used in lapidary work.
Geological facts
Chert breaks with a conchoidal fracture, creating sharp edges used by ancient humans for thousands of years. This specific piece shows clear 'flake scars' from intentional shaping.
Field identification & locations
Identify by looking for waxy luster and shell-like (conchoidal) fracture patterns. Often found in areas with limestone bedrock or ancient habitation sites. Note: Removing artifacts from public land is often illegal.
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