sedimentary
Chert (Arrowhead Fragment)
Microcrystalline Quartz (SiO2)
Hardness: 7 (Mohs scale); Color: Dark grey to black; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 7 (Mohs scale)
- Color
- Dark grey to black
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: Dark grey to black; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Chert can form as nodules in limestone or as distinct bedded deposits.
Uses & applications
Historically used for stone tools like arrowheads and scrapers due to its conchoidal fracture and sharp edges. Today used as a collector specimen or in industrial grinding media.
Geological facts
This specimen appears to be a lithic flake or a fragment of a projectile point (arrowhead), showing evidence of intentional 'knapping' or flaking by humans.
Field identification & locations
Identify by its waxy luster and shell-like (conchoidal) fracture patterns. Frequently found in stream beds or limestone outcrops. Check local laws before collecting artifacts.
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