sedimentary

Sandstone (Ferruginous)

Arenite (with high iron oxide content)

Hardness: 6-7 (Mohs scale); Color: Tan, brown, or reddish-yellow due to iron oxides; Luster: Dull/Earthy; Crystal structure: Primarily sand-sized grains of quartz (clastic); Cleavage: None; Specific Gravity: 2.2-2.8.

Hardness: 6-7 (Mohs scale)
Color: Tan, brown, or reddish-yellow due to iron oxides
Luster: Dull/Earthy

Identified April 11, 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 (primarily quartz and feldspar). These are deposited in environments like rivers, deserts, or beaches and compressed over millions of years (lithification). This specimen shows iron staining from weathering.

Uses & applications

Commonly used in construction as a building material, paving stones, and for landscaping. In some forms, it is a reservoir for water (aquifers) or oil and gas.

Geological facts

Sandstone accounts for approximately 20% of all sedimentary rocks on Earth. The distinct reddish-brown patches are 'limonitic' staining, caused by the oxidation of iron-bearing minerals within the rock.

Field identification & locations

Identify in the field by its gritty, sandpaper-like feel. It often exhibits visible layering or cross-bedding. Common in areas with ancient seafloors or riverbeds.

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