sedimentary
Pebble (Quartzite / Chert)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness 6.5–7 on the Mohs scale, sub-vitreous to dull luster, conchoidal to uneven fracture, and a tan to grayish-brown color.
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Physical properties
Hardness 6.5–7 on the Mohs scale, sub-vitreous to dull luster, conchoidal to uneven fracture, and a tan to grayish-brown color.
Formation & geological history
Formed via sedimentary compaction of siliceous sediments or metamorphism of quartz sandstone, subsequently rounded by mechanical fluvial or coastal erosion.
Uses & applications
Commonly used in aggregate for concrete, roadbeds, landscaping gravel, and decorative paving.
Geological facts
Naturally rounded river pebbles develop their smooth, rounded shapes after traveling dozens to hundreds of miles through turbulent streams.
Field identification & locations
Identified by its rounded water-worn shape, dull earthy surface, and ability to scratch glass. Widely distributed along riverbeds, beaches, and glacial gravel deposits.
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Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary