sedimentary
Chert (specifically a Lithic Flake)
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
Hardness: 7 (Mohs scale), Color: tan, grey, Luster: waxy to vitreous, Crystal Structure: Trigonal (microscopic), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6
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Physical properties
Hardness: 7 (Mohs scale), Color: tan, grey, Luster: waxy to vitreous, Crystal Structure: Trigonal (microscopic), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6
Formation & geological history
Formed through the accumulation of siliceous remains of organisms (like diatoms) or precipitation from silica-rich groundwater. This specific piece shows signs of anthropogenic modification (flaking).
Uses & applications
Historically used for stone tools due to sharp edges; currently used for geological study, road surfacing, or flintknapping.
Geological facts
This specimen appears to be a 'flake,' a byproduct of prehistoric toolmaking (knapping). Chert has a conchoidal fracture, which allows it to break like glass and produce razor-sharp edges.
Field identification & locations
Look for a bulb of percussion and ripples on the surface, indicating it was struck by a human. Commonly found in limestone outcrops or as river cobbles. Important for archaeological site identification.
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