sedimentary
Banded Chert
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy to vitreous luster, displays distinct alternating color bands of white, tan, and dark purple-black, and lacks crystal cleavage.
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Physical properties
Hardness of 7 on the Mohs scale, waxy to vitreous luster, displays distinct alternating color bands of white, tan, and dark purple-black, and lacks crystal cleavage.
Formation & geological history
Formed through the chemical precipitation of silica from seawater and subsequent diagenesis over millions of years within sedimentary layers.
Uses & applications
Historically used for making stone tools due to its conchoidal fracture; currently collected as a decorative lapidary material.
Geological facts
Banded varieties often form in marine environments where silica-rich fluids deposit layers rich in impurities like iron oxides.
Field identification & locations
Identify in the field by its extreme hardness, conchoidal fracture, and striking parallel color banding; commonly found in limestone and chalk formations worldwide.
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