sedimentary

Sandstone (Ferruginous/Red Sandstone)

Clastic sedimentary rock (primarily SiO2 with Fe2O3)

Hardness: 6-7 (on Mohs scale); Color: Reddish-brown to purple due to iron oxide; Luster: Dull/Earthy; Crystal Structure: Granular/Clastic; Cleavage: None (breaks across grains); Specific Gravity: 2.2 - 2.8

Hardness: 6-7 (on Mohs scale)
Color: Reddish-brown to purple due to iron oxide
Luster: Dull/Earthy

Identified April 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. The reddish hue indicates deposition in an oxidizing environment, likely a riverbed, desert, or floodplain. Geological age varies greatly by region, often associated with the Triassic or Devonian periods.

Uses & applications

Commonly used as a building material, paving stone, and in glass manufacturing or as an abrasive. Fine-grained varieties are used for sharpening tools.

Geological facts

Sandstone accounts for about 20% of all sedimentary rocks on Earth. The visible layering or 'bedding' seen in this specimen was created by tidal or current pulses during deposition.

Field identification & locations

Identify by its 'sandpaper' feel and visible layers (strata). It will not fizz with acid unless it has a calcitic cement. Found globally in basins and near ancient coastlines.

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