sedimentary
Sandstone Pebble (River Rock)
Arenite (primarily SiO2)
Hardness: 6-7 Mohs; Color: Tan, brown, or buff; Luster: Dull/Earthy; Crystal structure: Clastic (sand grains); Cleavage: None; Specific Gravity: 2.2-2.8.
- Hardness
- 6-7 Mohs
- Color
- Tan, brown, or buff
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 Mohs; Color: Tan, brown, or buff; Luster: Dull/Earthy; Crystal structure: Clastic (sand grains); Cleavage: None; Specific Gravity: 2.2-2.8.
Formation & geological history
Formed through the accumulation and cementation of mineral particles or rock fragments of sand size. This specimen displays significant rounding caused by fluvial (river) or coastal erosion over centuries.
Uses & applications
Used in construction as a base material, landscaping, decorative pathways, and as an educational tool for learning about the rock cycle.
Geological facts
Sandstone can preserve fossilized footprints or ripple marks from ancient riverbeds. This specific shape is known as a 'clast' that has been smoothed by the mechanical action of water and other rocks.
Field identification & locations
Identified by its gritty texture (feels like sandpaper) and rounded, water-worn edges. Commonly found in riverbeds, deltas, and beaches. Collectors look for unique shapes or colors.
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