sedimentary
Flint Pebble
Sedimentary cryptocrystalline quartz (SiO2)
Hardness of 7 on the Mohs scale, typically dark grey, black, or brown with a waxy to vitreous luster, conchoidal fracture, and no true cleavage.
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Physical properties
Hardness of 7 on the Mohs scale, typically dark grey, black, or brown with a waxy to vitreous luster, conchoidal fracture, and no true cleavage.
Formation & geological history
Formed through the chemical replacement of calcium carbonate in chalk or limestone by silica-rich solutions during the Cretaceous period.
Uses & applications
Historically used for making stone tools, arrowheads, and striking fire; currently used in aggregate, ceramics, and by beachcombers and lapidary collectors.
Geological facts
Flint and chert are essentially the same material, though 'flint' typically refers specifically to the variety found in chalk deposits. It was one of the earliest materials manipulated by human ancestors for technology.
Field identification & locations
Easily identified by its dark color, smooth water-worn pebble shape on beaches, and sharp, conchoidal broken edges that reveal a lighter cortex or inner material. Commonly found in chalk cliff regions and associated beaches.
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