sedimentary
Siltstone / Fine Sandstone Pebble
Sedimentary Rock (Quartz, Feldspar, Clay Minerals)
Hardness: 5.5-6.5 on Mohs scale. Color: Dark greyish-brown with fine texture. Luster: Dull to earthy. Grain size: Microscopic to fine. Cleavage: None (conchoidal to irregular fracture).
- Hardness
- 5
- Color
- Dark greyish-brown with fine texture
- Luster
- Dull to earthy
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Physical properties
Hardness: 5.5-6.5 on Mohs scale. Color: Dark greyish-brown with fine texture. Luster: Dull to earthy. Grain size: Microscopic to fine. Cleavage: None (conchoidal to irregular fracture).
Formation & geological history
Formed through the compaction and cementation of silt and sand particles deposited by water or wind in riverbeds, lakes, or marine environments over millions of years, later rounded by stream or river erosion.
Uses & applications
Commonly used in gravel, construction aggregate, landscaping, and educational collections.
Geological facts
River-worn pebbles like this acquire their smooth, elongated shape through mechanical abrasion as water rolls them against other rocks along river beds or shorelines.
Field identification & locations
Identified by its fine grain, dull earthy appearance, smooth water-worn surface, and dark grey coloration. Commonly found in riverbeds, glacial tills, and beaches worldwide.
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