sedimentary
River Pebble (Quartz-rich)
Silicon Dioxide (SiO2) with various inclusions
Hardness: 7 (Mohs scale), Color: Off-white/grey/creamy, Luster: Dull to waxy when unpolished, Crystal Structure: Trigonal (microcrystalline), Cleavage: None, Specific Gravity: 2.65
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale), Color: Off-white/grey/creamy, Luster: Dull to waxy when unpolished, Crystal Structure: Trigonal (microcrystalline), Cleavage: None, Specific Gravity: 2.65
Formation & geological history
Formed through mechanical weathering and erosion of larger rock formations. It has been rounded and smoothed over time by the action of moving water in a river or coastal environment.
Uses & applications
Primarily used in decorative landscaping, construction aggregate, aquarium substrate, and as a material for tumbling and polishing by hobbyists.
Geological facts
River pebbles are geological travelers; their smooth surface is the result of thousands of years of constant tumbling against other rocks, which polishes away sharp edges.
Field identification & locations
Identified by its smooth, rounded egg-like shape and lack of sharp edges. Commonly found in riverbeds, glacial deposits, and beaches. Collectors look for unique colors or translucency.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary