
sedimentary
Sandstone (Ferruginous)
Clastic sedimentary rock (primarily SiO2 with Fe2O3 cement)
Hardness: 6-7 (Mohs scale), Color: Brownish-red to tan, Luster: Dull/Earthy, structure: Clastic (fine-grained sand), Cleavage: None/Irregular fracture, Specific Gravity: 2.2-2.8
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Brownish-red to tan, Luster: Dull/Earthy, structure: Clastic (fine-grained sand), Cleavage: None/Irregular fracture, Specific Gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. This specimen shows signs of iron oxide (hematite/limonite) cementation which gives it the brown color, likely rounded by water erosion in a fluvial or beach environment.
Uses & applications
Used in construction, as a building material, for paving stones, and sometimes in glass manufacturing if pure enough. This specific pebble size is common in landscaping gravel.
Geological facts
Sandstone accounts for about 20% of all sedimentary rocks on Earth. The layers within sandstone can often record ancient environments like deserts, rivers, or oceans through a process called cross-bedding.
Field identification & locations
Identify in the field by its gritty 'sandpaper' feel and visible small grains. Often found in riverbeds, canyons, and coastal areas. Collectors look for unique banding or fossil inclusions.
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