sedimentary
Banded Chert
Microcrystalline quartz (SiO2)
Hardness of 7 on the Mohs scale, colors ranging from gray to brown with distinct darker bands, waxy to vitreous luster, cryptocrystalline structure, conchoidal fracture, specific gravity around 2.60-2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors ranging from gray to brown with distinct darker bands, waxy to vitreous luster, cryptocrystalline structure, conchoidal fracture, specific gravity around 2.60-2.65.
Formation & geological history
Formed through the accumulation of silica-rich microfossils or inorganic precipitation from silica-rich solutions, followed by diagenesis and lithification in marine environments over millions of years.
Uses & applications
Used primarily in lapidary work, making stone tools in antiquity, decorative tumbling, and gemstone collection.
Geological facts
Chert has been utilized by humans for stone tools since the Paleolithic era due to its ability to fracture conchoidally and produce extremely sharp edges.
Field identification & locations
Found globally in marine sedimentary sequences, particularly within limestone and chalk formations. Identify by its high hardness, conchoidal fracture, and characteristic banding.
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