sedimentary
Sandstone (Ferruginous)
Arenite with Iron Oxide (Fe2O3) cement
Hardness: 6-7 (on Mohs scale); Color: reddish-brown or tan; Luster: dull/earthy; Crystal structure: clastic texture with visible sand-sized grains; Specific gravity: approx. 2.2-2.8; Cleavage: none (fractures irregularly).
- Hardness
- 6-7 (on Mohs scale)
- Color
- reddish-brown or tan
- Luster
- dull/earthy
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Physical properties
Hardness: 6-7 (on Mohs scale); Color: reddish-brown or tan; Luster: dull/earthy; Crystal structure: clastic texture with visible sand-sized grains; Specific gravity: approx. 2.2-2.8; Cleavage: none (fractures irregularly).
Formation & geological history
Formed through the accumulation and compaction of mineral particles or rock fragments (detritus). This specific rounded specimen underwent significant water erosion in a high-energy environment like a riverbed or coastal area. Geological age varies greatly from millions to hundreds of millions of years old.
Uses & applications
Commonly used as a building material in architecture, paving stone, and in the manufacturing of glass or grinding wheels. It is also a primary reservoir rock for oil, natural gas, and groundwater.
Geological facts
Sandstone is one of the most common types of sedimentary rock and makes up about 10-20% of the Earth's sedimentary crust. The reddish color in this specimen is due to the presence of iron oxide (hematite) acting as a natural cement.
Field identification & locations
Identify by its gritty, sandpaper-like feel and the visible grains of quartz or feldspar. It is found globally in basins, riverbeds, and deserts. Collectors should look for unique banding or rounding shapes caused by natural weathering.
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