Sandstone (likely Arkose)

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Tan, brown, or buff; Luster: Dull/Earthy; Crystal structure: Clastic (granular); Cleavage: None; Specific gravity: 2.2-2.8.

Formation & Geological History

Formed through the accumulation and cementation of sand-sized mineral grains, often in riverbeds, deltas, or desert environments. This specimen appears to be an arkose sandstone, which forms from the rapid weathering of granitic rocks.

Uses & Applications

Used widely in construction for paving, building blocks, and decorative stone. Also used as a reservoir rock for oil and gas or for groundwater aquifers.

Geological Facts

Sandstone makes up about 10-25% of the sedimentary rock on Earth. It is famous for creating dramatic landscapes like the Grand Canyon and the red rocks of Sedona.

Field Identification & Locations

Identify in the field by its gritty 'sandpaper' feel. Look for visible layers (bedding) and grains of quartz and feldspar. Found globally in basins and mountainous regions.

Identified on: 4/21/2026

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