sedimentary

Sandstone (Ferruginous)

Arenite with Iron Oxide cement (SiO2 + Fe2O3)

Hardness: 6-7 (on Quartz grains). Color: Yellowish-brown to reddish-tan. Luster: Dull/Earthy. Structure: Massive or layered; clastic texture with visible sand grains. Cleavage: None. Specific Gravity: 2.2 - 2.8.

Hardness: 6-7 (on Quartz grains)
Color: Yellowish-brown to reddish-tan
Luster: Dull/Earthy

Identified April 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the accumulation and lithification of sand-sized mineral particles. The yellow/brown coloring is due to the presence of iron oxide (Limonite or Goethite) acting as a cementing agent during diagenesis in oxygen-rich environments.

Uses & applications

Primary uses include building stone, aggregate for construction, and as a reservoir rock for water, oil, and gas. Varieties with high iron content were historically used as iron ore (ironstone).

Geological facts

Sandstone makes up about 20% to 25% of all sedimentary rocks on Earth. The coloring is often a result of 'rusting' minerals within the stone, which can create aesthetic banded patterns known as Liesegang rings.

Field identification & locations

Identify by its gritty, sandpaper-like feel and visible grains. It is commonly found in river beds, deserts, and coastal areas. It will not fizz with acid unless carbonate cement is present.

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