sedimentary
Chert / Flint (or lithic artifact flake)
Microcrystalline Quartz (SiO2)
Hardness 7 on Mohs scale; tan, yellowish-brown, or earth-toned color; dull to waxy luster; conchoidal fracture with sharp, shell-like edges; cryptocrystalline micro-structure; specific gravity ~2.65.
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Physical properties
Hardness 7 on Mohs scale; tan, yellowish-brown, or earth-toned color; dull to waxy luster; conchoidal fracture with sharp, shell-like edges; cryptocrystalline micro-structure; specific gravity ~2.65.
Formation & geological history
Forms primarily as nodules or beds in sedimentary rocks, such as limestone or chalk, from the precipitation of microcrystalline silica derived from biogenic sources like radiolarians or diatoms.
Uses & applications
Historically used by indigenous peoples to create sharp tools, arrowheads, and scrapers due to its predictable conchoidal fracture. Modern uses include gravel, road stone, and flintknapping crafts.
Geological facts
This specimen displays distinct flaking scars and sharp margins typical of knapped chert or a stone tool debitage (flake). Chert played a vital role in human prehistory as one of the primary materials for tool manufacturing.
Field identification & locations
Identified by its microcrystalline texture, hardness (scratches glass easily), smooth surface texture, and distinct shell-shaped (conchoidal) fractures. Found globally in limestone formations and river gravels.
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