sedimentary

Quartz Pebble

Silicon dioxide (SiO2)

Mohs hardness of 7, transparent to translucent with a vitreous luster, lacks cleavage, and has a specific gravity of 2.65.

Identified October 25, 2026More sedimentary →

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Physical properties

Mohs hardness of 7, transparent to translucent with a vitreous luster, lacks cleavage, and has a specific gravity of 2.65.

Formed through the physical weathering and water-transport abrasion of primary quartz-bearing rocks over thousands to millions of years.

Used in landscaping, decorative gravel, aggregate for construction, and as raw material for glass production.

Quartz is one of the most abundant and durable minerals on Earth's continental crust, surviving weathering that destroys other minerals.

Identified by its high hardness that scratches glass, lack of cleavage, and smooth, rounded shape found 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

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone or Siltstone

Arenite (if sandstone)

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)