sedimentary
River Pebble (Sandstone)
Clastic Sedimentary Rock (Sandstone)
Hardness: 6-7 Mohs; Color: Tan, beige, and grey; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific gravity: 2.2-2.8
- Hardness
- 6-7 Mohs
- Color
- Tan, beige, and grey
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 Mohs; Color: Tan, beige, and grey; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. This specimen shows significant rounding due to water erosion (fluvial transport) over hundreds to thousands of years.
Uses & applications
Primarily used in landscaping, construction as aggregate, and sometimes in decorative masonry. Smoothed river stones are often used for decorative garden paths or in fish tanks.
Geological facts
The rounded shape indicates that this rock has traveled a long distance in a river or creek bed, where constant tumbling against other rocks has smoothed away its sharp edges.
Field identification & locations
Identify in the field by its rounded, smooth texture and sandy granular appearance under a magnifying glass. Commonly found in riverbeds, old glacial deposits, and along coastal beaches.
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