sedimentary
Chert / Flint Pebble
Microcrystalline Silica (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: tan, buff, or light brown with occasional dark banding, Luster: dull to waxy, Crystal structure: cryptocrystalline, Cleavage: none (conchoidal fracture), Specific Gravity: 2.5-2.8
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Physical properties
Hardness: 7 (Mohs scale), Color: tan, buff, or light brown with occasional dark banding, Luster: dull to waxy, Crystal structure: cryptocrystalline, Cleavage: none (conchoidal fracture), Specific Gravity: 2.5-2.8
Formation & geological history
Formed through the precipitation of silica from groundwater or within carbonate sedimentary rocks like limestone. Often originates as nodules or layers in marine environments through chemical replacement.
Uses & applications
Primarily used in construction as aggregate, historical use as tool and weapon material (arrowheads), and as a fire-starting tool.
Geological facts
Chert was one of the most important minerals for early humans because its conchoidal fracture allows it to be shaped into razor-sharp edges. It is extremely resistant to chemical weathering.
Field identification & locations
Identify in the field by its hardness (scratches glass), waxy feel when smooth, and sharp edges where broken. Commonly found in gravel pits, riverbeds, and weathered limestone outcrops.
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