sedimentary
Sandstone (River Pebble)
Arenite (primarily SiO2)
Hardness: 6-7 Mohs; Color: Tan to light brown with darker wet patches; Luster: Dull/Earthy; Crystal structure: Granular (clastic); Cleavage: None; Specific gravity: 2.2-2.8
- Hardness
- 6-7 Mohs
- Color
- Tan to light brown with darker wet patches
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 Mohs; Color: Tan to light brown with darker wet patches; Luster: Dull/Earthy; Crystal structure: Granular (clastic); Cleavage: None; Specific gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation, compaction, and cementation of sand-sized mineral grains or rock fragments over millions of years. This specimen shows signs of mechanical weathering and rounding from fluvial (river) transport environments.
Uses & applications
Commonly used as construction aggregate, decorative landscaping stone, and occasionally for making grindstones or building facades. Smooth pebbles are popular for home decor and zen gardens.
Geological facts
Sandstone represents about 20% of all sedimentary rocks on Earth. Its porosity makes it a primary reservoir for underground water (aquifers) and petroleum.
Field identification & locations
Identified by its gritty sandpaper-like texture and visible sand grains. It is extremely common in riverbeds, beaches, and desert environments globally. Collectors look for unique banding or fossils within the matrix.
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