sedimentary
Chert (Flint nodule)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on Mohs scale; waxy to dull luster, conchoidal fracture, and a brownish-gray interior surrounded by a pale weathering rind (cortex).
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Physical properties
Hardness of 7 on Mohs scale; waxy to dull luster, conchoidal fracture, and a brownish-gray interior surrounded by a pale weathering rind (cortex).
Formation & geological history
Formed biochemically or diagenetically by precipitation of silica from siliceous organism remains (like radiolarians or sponge spicules) within chalk or limestone beds.
Uses & applications
Historically used for making knapped stone tools and fire-starting; currently used in gravel, road construction, and decorative landscaping.
Geological facts
When struck with steel or another hard stone, flint sparks easily, making it one of the earliest technological materials used by early humans for fire and weaponry.
Field identification & locations
Identifiable by its smooth, shell-like conchoidal fracture, high hardness (scratches glass), and chalky exterior crust; widely found in Cretaceous chalk and marine limestone formations worldwide.
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