sedimentary
Flint / Chert (Fossiliferous)
Silicon dioxide (SiO2) with microcrystalline quartz
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, colors range from dark grey/black to brown and white with iron-oxide staining.
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Physical properties
Hardness of 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, colors range from dark grey/black to brown and white with iron-oxide staining.
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, weapons, and fire-starting; today used in landscaping, road construction, and decorative displays.
Geological facts
This specimen contains distinct fossilized inclusions (such as ancient sponge spicules or microfossils), creating the ring-like and dotted patterns visible on the surface.
Field identification & locations
Easily identified by its extremely high hardness, conchoidal fracture, and characteristic weathering rind often found on chalk cliffs and beaches.
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