sedimentary
Flint
Cryptocrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness 7 on the Mohs scale, color ranges from dark grey to brown, waxy to vitreous luster, conchoidal fracture with no cleavage.
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Physical properties
Hardness 7 on the Mohs scale, color ranges from dark grey to brown, waxy to vitreous luster, conchoidal fracture with no cleavage.
Formation & geological history
Formed as nodules in sedimentary rocks like chalk and limestone through the replacement of calcium carbonate by silica-rich solutions.
Uses & applications
Historically used for making stone tools and fire-starting, and modernly used in abrasives and construction aggregates.
Geological facts
Flint played a critical role in human technological evolution during the Stone Age due to its ability to be chipped into extremely sharp edges.
Field identification & locations
Identify by its distinctive conchoidal fracture, waxy luster, and ability to spark when struck against steel. Found globally in chalk formations.
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Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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