sedimentary

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness of 7 on the Mohs scale, typically brown to tan due to staining, vitreous luster, and trigonal crystal system.

Identified November 4, 2026More sedimentary →

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Physical properties

Hardness of 7 on the Mohs scale, typically brown to tan due to staining, vitreous luster, and trigonal crystal system.

Formed through the physical weathering and aqueous transport of parent quartz rocks, often deposited in riverbeds or beaches over millions of years.

Used in landscaping, decorative gravel, abrasive manufacturing, and as a common specimen for beginner rock collectors.

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

Identified easily by its high hardness which scratches glass and lack of cleavage; found globally in alluvial deposits, rivers, and coastal areas.

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)