sedimentary
Sandstone (Greywacke)
Arenite / Greywacke Sandstone
Hardness: 6-7 (Mohs scale), Color: Dull grey to tan, Luster: Dull/Earthy, Crystal Structure: Microcrystalline with visible sand-sized grains, Cleavage: None, Specific Gravity: 2.2-2.8
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Dull grey to tan, Luster: Dull/Earthy, Crystal Structure: Microcrystalline with visible sand-sized grains, Cleavage: None, Specific Gravity: 2.2-2.8
Formation & geological history
Formed from the accumulation and cementation of mineral particles or rock fragments of sand size (0.0625 to 2 mm) in environments like riverbeds, beaches, or shallow seas. This specimen likely weathered into its smooth shape via water abrasion.
Uses & applications
Common architectural stone, used as a construction aggregate, for road base, or in glass manufacturing if the quartz content is high.
Geological facts
Sandstone is one of the most common sedimentary rocks on Earth. Greywacke variants specifically are known as 'dirty' sandstones because of their high clay content and varied mineral makeup.
Field identification & locations
Identify by its gritty texture (feels like sandpaper) and visible layering if present. Found globally in riverbeds, coastlines, and sedimentary basins.
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