sedimentary
Chert (Flint/Jasper variety)
Silicon Dioxide (SiO2)
Hardness of 7 on the Mohs scale, waxy or vitreous luster, conchoidal fracture with no cleavage, yellow to tan and brown coloration, microcrystalline or cryptocrystalline quartz structure.
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Physical properties
Hardness of 7 on the Mohs scale, waxy or vitreous luster, conchoidal fracture with no cleavage, yellow to tan and brown coloration, microcrystalline or cryptocrystalline quartz structure.
Formation & geological history
Formed by the chemical precipitation of silica from aqueous solutions or the accumulation of siliceous skeletal remains of microscopic organisms (such as diatoms or radiolarians) in marine environments.
Uses & applications
Historically used for making stone tools, arrowheads, and fire-starting (flint and steel); currently used in abrasive products and as decorative landscaping or tumbling stones.
Geological facts
Chert is extremely durable and has been utilized by humans for hundreds of thousands of years due to its ability to fracture into extremely sharp edges (conchoidal fracture).
Field identification & locations
Identified in the field by its characteristic waxy luster, conchoidal fracture surfaces, and high hardness capable of scratching glass. Commonly found in limestone and chalk formations worldwide.
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