sedimentary and metamorphic
River Pebbles (Sandstone and Quartzite)
SiO2 (Quartz) dominated clastic rocks
Hardness: 6-7 (Mohs/Quartz based), Color: Grey, tan, buff, and reddish-brown, Luster: Dull to matte (waxy when wet), Structure: Granular or microcrystalline, Cleavage: None/Conchoidal fractures, Specific Gravity: 2.6 - 2.8
Identified More sedimentary and metamorphic →
Explore River Pebbles (Sandstone and Quartzite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 (Mohs/Quartz based), Color: Grey, tan, buff, and reddish-brown, Luster: Dull to matte (waxy when wet), Structure: Granular or microcrystalline, Cleavage: None/Conchoidal fractures, Specific Gravity: 2.6 - 2.8
Formation & geological history
Formed through the accumulation of sand grains (sandstone) or the heat/pressure alteration of sandstone (quartzite). These specimens have been smoothed and rounded by high-energy water transport (fluvial or beach action) over many years.
Uses & applications
Landscaping, drainage control, decorative aquarium use, small-scale construction aggregate, and as 'pocket stones' for casual collectors.
Geological facts
River stones can travel hundreds of miles from their geological source. Their perfectly rounded shape is a direct result of 'abrasion'—the grinding of stones against each other in moving water.
Field identification & locations
Identify in the field by their smooth, rounded edges and lack of sharp corners. They are ubiquitous in riverbeds, glacial deposits, and coastal shorelines. Collectors look for unique patterns or colors within the smoothness.
More like this
Other sedimentary and metamorphic specimens
Shale or Argillite
Shale (sedimentary) / Argillite (metamorphic)
Sedimentary or Metamorphic (low-grade)
Anthracite Coal
Anthracite (Carbon-rich Sedimentary-to-Metamorphic Rock)
metamorphic
Milky Quartz with Iron Inclusions
Quartz (Silicon Dioxide, SiO2)
mineral
Anthracite Coal
Anthracite (Carbon-based sedimentary-derived metamorphic rock)
metamorphic
River Pebbles and Quartz
Mixed Igneous, Sedimentary, and Metamorphic Rocks (Silicon Dioxide SiO2 dominant)
mixed
Calcite
Calcite (CaCO3)
Mineral