sedimentary

Quartz pebble

Silicon dioxide (SiO2)

Hardness of 7 on the Mohs scale, yellowish-brown color from iron staining, vitreous luster, and conchoidal fracture.

Identified November 8, 2026More sedimentary →

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Physical properties

Hardness of 7 on the Mohs scale, yellowish-brown color from iron staining, vitreous luster, and conchoidal fracture.

Formed through mechanical weathering and aqueous transport of primary quartz, rounding over long periods in rivers or beach environments.

Used in landscaping, decorative gravel, tumbling, and as a raw material for silicon extraction.

Quartz is one of the most durable and abundant minerals on Earth, highly resistant to both chemical and mechanical weathering.

Identified by its high hardness, inability to be scratched by steel, and smooth, water-worn shape; found worldwide in riverbeds and beaches.

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

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)