sedimentary
Chert (Arrowhead/Projectile Point)
Microcrystalline quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: Brown, gray, black; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
- Hardness
- 6
- Color
- Brown, gray, black
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brown, gray, black; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
Formation & geological history
Formed as nodules or beds in limestone/chalk through the accumulation of siliceous remains or chemical precipitation. This specific specimen was later anthropogenically modified by flintknapping.
Uses & applications
Historically used for tools and weapons; currently valued as an archaeological artifact and for lapidary use.
Geological facts
Chert was one of the first materials used by early humans for tools because its conchoidal fracture produces extremely sharp edges. This specimen is an arrowhead, specifically a projectile point.
Field identification & locations
Identify by its waxy luster, hardness (scratches glass), and distinct shell-like (conchoidal) fracture scars from knapping. Found globally in sedimentary basins.
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