sedimentary
Chert (Arrowhead Artifact)
Chert (SiO2)
Hardness: 7 (Mohs scale), Color: Brown/Grey, Luster: Waxy to dull, Crystal Structure: Microcrystalline quartz, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Brown/Grey, Luster: Waxy to dull, Crystal Structure: Microcrystalline quartz, 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 radiolarians). This specimen was later culturally modified by flintknapping.
Uses & applications
Historically used for stone tools and weapons (projectile points); currently valued as an archaeological artifact and for hobbyist flintknapping.
Geological facts
Chert was one of the most important raw materials for early humans because its conchoidal fracture allows it to be shaped into razor-sharp edges.
Field identification & locations
Identify by the waxy texture, extreme hardness (scratches glass), and the presence of flake scars from intentional sharpening. Commonly found in riverbeds or eroded limestone deposits.
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