sedimentary
Chert (Arrowheads)
Microcrystalline Quartz (SiO2)
Hardness 7.0 on Mohs scale, waxy to dull luster, conchoidal fracture, various brown and reddish colors, opaque to translucent.
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Physical properties
Hardness 7.0 on Mohs scale, waxy to dull luster, conchoidal fracture, various brown and reddish colors, opaque to translucent.
Formation & geological history
Formed as nodules or beds in sedimentary rock through the accumulation of siliceous organisms or silica precipitation. These specific shapes are man-made (knapped) artifacts.
Uses & applications
Historically used for tools and weapons; currently valued as archaeological artifacts and collectibles.
Geological facts
Chert and flint were the primary materials for stone-age technology because their conchoidal fracture patterns allow for extremely sharp edges.
Field identification & locations
Identify by the presence of 'flake scars' from pressure flaking; commonly found in areas previously inhabited by indigenous populations near water sources.
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Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
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Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
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Chert Breccia
Brecciated Chert (Microcrystalline Silica)
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Shale or Slaty Mudstone
Argillaceous sedimentary rock
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Sandstone
Arenite (primarily SiO2)
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