sedimentary
Sandstone (likely Ferruginous)
Arenite (primarily SiO2 with Fe2O3 staining)
Hardness: 6-7 (individual grains); Color: terracotta/orange/red due to iron oxide; Luster: dull/earthy; Crystal structure: granular/clastic; Cleavage: none; Specific gravity: 2.2-2.8
- Hardness
- 6-7 (individual grains)
- Color
- terracotta/orange/red due to iron oxide
- Luster
- dull/earthy
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Physical properties
Hardness: 6-7 (individual grains); Color: terracotta/orange/red due to iron oxide; Luster: dull/earthy; Crystal structure: granular/clastic; Cleavage: none; Specific gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation of sand-sized mineral grains or rock fragments, subsequently lithified by mineral cement (silica or calcium carbonate) over millions of years. This specimen appears water-worn, potentially from a river or coastal environment.
Uses & applications
Construction aggregate, architectural stone, decorative landscaping, and occasionally used for grindstones or oil/gas reservoirs due to porosity.
Geological facts
The orange-red color is caused by the oxidation of iron-bearing minerals, essentially 'rusting' the rock. This specimen shows a smooth, rounded shape indicating significant transport by water.
Field identification & locations
Identify in the field by its gritty texture (feels like sandpaper) and visible sand grains. These are commonly found in desert basins, riverbeds, and coastal cliffs.
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