sedimentary
Flint
SiO2 (Microcrystalline Quartz / Chert)
Hardness of 7 on the Mohs scale, typically dark grey, black, or brown in color, waxy to vitreous luster, cryptocrystalline structure, exhibits conchoidal fracture with no true cleavage, specific gravity of 2.60-2.65.
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Physical properties
Hardness of 7 on the Mohs scale, typically dark grey, black, or brown in color, waxy to vitreous luster, cryptocrystalline structure, exhibits conchoidal fracture with no true cleavage, specific gravity of 2.60-2.65.
Formation & geological history
Formed as nodules or masses in sedimentary rocks such as chalk and marine limestones by the replacement of calcium carbonate with silica-rich solutions over millions of years.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire. Today primarily used in landscaping, road construction, and abrasive materials.
Geological facts
Flint played a critical role in human technological evolution during the Stone Age due to its ability to fracture into extremely sharp edges.
Field identification & locations
Identified easily by its conchoidal fracture, waxy luster, and ability to produce sparks when struck against steel. Found globally in chalk formations.
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