sedimentary
Chert / Flint pebble
Microcrystalline quartz (SiO2)
Hardness: 7 (Mohs scale), Color: Brownish-tan/gray, Luster: Waxy to dull, Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: Brownish-tan/gray, Luster: Waxy to dull, Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine or lacqustrine environments, often replacing carbonate rocks.
Uses & applications
Historically used for tool making (arrowheads/knives) and fire-starting (flint); currently used as architectural decoration, road aggregate, and for landscaping.
Geological facts
Flint is a variety of chert that was essential for human survival in the Stone Age due to its ability to fracture into extremely sharp edges.
Field identification & locations
Identify in the field by its waxy luster, hardness (it can scratch glass), and its characteristic smooth, curved conchoidal fractures. Commonly found in limestone or chalk beds.
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