sedimentary
Chert (Flint)
Silicon Dioxide (SiO2)
Hardness: 7 (Mohs scale), Color: tan/beige/gray, Luster: waxy to dull, Structure: microcrystalline quartz, Fracture: conchoidal (shell-like), specific gravity: 2.6
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Physical properties
Hardness: 7 (Mohs scale), Color: tan/beige/gray, Luster: waxy to dull, Structure: microcrystalline quartz, Fracture: conchoidal (shell-like), specific gravity: 2.6
Formation & geological history
Formed through the accumulation of silica-rich organic remains (like radiolaria or diatoms) or by chemical precipitation from groundwater within limestone or chalk beds.
Uses & applications
Historically used for stone tools and weapons. Currently used in road construction, as an abrasive, and sometimes in jewelry (e.g., as jasper).
Geological facts
Chert was one of the most important materials for early humans because its conchoidal fracture allows it to be shaped into razor-sharp edges for arrowheads and scrapers.
Field identification & locations
Identify in the field by its hardness (scratches glass), waxy feel, and curved, sharp-edged break patterns. Common in sedimentary basins worldwide.
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