sedimentary
Chert
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: Tan, beige, brown; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Tan, beige, brown
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: Tan, beige, brown; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Forms primarily as nodules or beds in sedimentary rocks through the accumulation of silica-rich organic remains or chemical precipitation. Found in various geological eras.
Uses & applications
Historically used for stone tools due to sharp edges; currently used in construction as road metal and in lapidary work for tumbled stones and cabochons.
Geological facts
Flint is a dark variety of chert. It has been used since the Stone Age for making arrowheads and spear points because of the way it fractures into sharp edges.
Field identification & locations
Identified by its waxy appearance, extreme hardness (scratches glass), and distinctive shell-like (conchoidal) fracture pattern. Common in limestone deposits.
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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
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Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary