sedimentary
Siltstone Pebble
Siltstone
Hardness: 6-7 (Mohs), Color: Light to dark grey, Luster: Dull/Earthy, Crystal structure: Clastic (fine-grained), Cleavage: None, Specific gravity: 2.6
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Physical properties
Hardness: 6-7 (Mohs), Color: Light to dark grey, Luster: Dull/Earthy, Crystal structure: Clastic (fine-grained), Cleavage: None, Specific gravity: 2.6
Formation & geological history
Formed through the lithification of silt-sized particles deposited in slow-moving water environments like floodplains or deltaic regions. This specific specimen has been rounded into a pebble by fluvial or glacial erosion.
Uses & applications
Used primarily as fill material in construction, as aggregate, or occasionally as decorative stones in landscaping.
Geological facts
Siltstone is intermediate between sandstone and shale. While it looks similar to shale, it lacks the thin layering (fissility) that causes shale to split into flat sheets.
Field identification & locations
Identify by its gritty feel (it will feel like very fine sandpaper on the teeth) and its lack of visible grains compared to sandstone. Commonly found in riverbeds and on beaches.
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