sedimentary
Quartz (Chert/Flint variety)
Silicon Dioxide (SiO2)
Hardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, white to brownish-gray color, microcrystalline crystal structure.
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Physical properties
Hardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, white to brownish-gray color, microcrystalline crystal structure.
Formation & geological history
Formed in marine environments through the precipitation of silica from seawater or the replacement of calcium carbonate by silica in limestone, typically during the Cretaceous period or earlier.
Uses & applications
Used historically for stone tools and fire-starting, and currently in lapidary arts, decorative items, and sometimes landscaping.
Geological facts
Chert and flint are essentially the same material, with 'flint' typically referring to darker varieties found in chalk deposits. It was one of the earliest materials utilized by humans for making sharp implements.
Field identification & locations
Easily identifiable by its extreme hardness, smooth conchoidal fracture edges, and lack of cleavage. Commonly found worldwide in limestone and chalk formations.
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