sedimentary

Arkosic Sandstone

Arkose

Hardness: 6-7 (on Mohs scale); Color: Pinkish-red to brownish orange; Luster: Dull/Earthy; Crystal Structure: Clastic (granular); Cleavage: None (fractures across grains); Specific Gravity: 2.5-2.7

Hardness: 6-7 (on Mohs scale)
Color: Pinkish-red to brownish orange
Luster: Dull/Earthy

Identified March 27, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (on Mohs scale); Color: Pinkish-red to brownish orange; Luster: Dull/Earthy; Crystal Structure: Clastic (granular); Cleavage: None (fractures across grains); Specific Gravity: 2.5-2.7

Formation & geological history

Formed from the weathering of feldspar-rich igneous rocks like granite. It is typically deposited in high-energy environments like alluvial fans or rapid river currents before the feldspar has time to chemically weather into clay.

Uses & applications

Used primarily in the construction industry as a building stone, in road base materials, or crushed for concrete aggregate. Occasionally used as a decorative architectural stone.

Geological facts

Arkosic sandstone is often referred to as 'dirty' or 'immature' sandstone because it contains a high percentage of feldspar (at least 25%), which usually disappears quickly through weathering in typical geological cycles.

Field identification & locations

Identify in the field by its distinct pinkish color and visible, angular grains of feldspar and quartz that give it a sandpaper-like texture. Common in rift basins and near granitic mountain ranges.