sedimentary

Chert

Microcrystalline quartz (SiO2)

Hardness of 7 on Mohs scale; colors range from brown, gray, to white; waxy to vitreous luster; conchoidal fracture.

Identified November 13, 2026More sedimentary →

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Physical properties

Hardness of 7 on Mohs scale; colors range from brown, gray, to white; waxy to vitreous luster; conchoidal fracture.

Formed through the chemical precipitation of silica from seawater or the accumulation of siliceous skeletal remains of micro-organisms.

Historically used for making stone tools and arrowheads due to its sharp edges when fractured; occasionally used for decorative landscaping.

Chert forms nodules or layers within sedimentary rocks like limestone and chalk, and varieties include flint, jasper, and agate.

Identify by its distinctive conchoidal fracture and high hardness that scratches glass. Found worldwide in marine sedimentary deposits.

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

Sandstone or Siltstone

Arenite (if sandstone)

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Shale

Fissile Sedimentary Rock

Sandstone

Arenite

Shale

Clastic sedimentary rock