sedimentary
Flint
Microcrystalline quartz (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, typically dark gray, brown, or black with a waxy to vitreous luster and conchoidal fracture.
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Physical properties
Hardness of 7 on the Mohs scale, typically dark gray, brown, or black with a waxy to vitreous luster and conchoidal fracture.
Formation & geological history
Forms through the chemical replacement of calcium carbonate in limestone by silica-rich solutions during the Cretaceous period.
Uses & applications
Historically used for making stone tools and fire-starting; currently used in abrasives, ceramics, and ornamental displays.
Geological facts
Flint produces sparks when struck against steel due to its high hardness and brittle nature, making it vital for ancient survival.
Field identification & locations
Easily identified by its sharp conchoidal edges and waxy luster, commonly found inside chalk and limestone formations worldwide.
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Other sedimentary specimens
Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion
Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary