sedimentary
Chert (Arrowhead or Flake)
Microcrystalline quartz (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-green to translucent; Luster: Waxy to vitreous; Structure: Microcrystalline with conchoidal (shell-like) fracture; Cleavage: None.
- Hardness
- 7 on Mohs scale
- Color
- Grayish-green to translucent
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-green to translucent; Luster: Waxy to vitreous; Structure: Microcrystalline with conchoidal (shell-like) fracture; Cleavage: None.
Formation & geological history
Formed as chemical precipitates in marine environments or through the replacement of limestone. This specific piece shows signs of anthropogenic modification (pressure flaking), suggesting it was worked by humans into a tool or projectile point.
Uses & applications
Historically used for stone tools (knives, arrowheads, scrapers) due to its sharp edges. Modernly used in construction aggregate and as a collector's item.
Geological facts
Chert breaks with a conchoidal fracture, creating edges that are sharper than a surgical scalpel. This specimen appears to be an artifact, specifically a lithic flake or the base of an arrowhead.
Field identification & locations
Identify in the field by its waxy texture and shell-like curved breaks. Found globally in limestone beds or as river cobbles. Look for 'scars' from where flakes were removed by early humans.
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