Sandstone (Ferruginous)

Physical Properties

Hardness: 6-7 (Mohs); Color: Tan to reddish-brown; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Specific Gravity: 2.2-2.8; Texture: Gritty like sandpaper.

Formation & Geological History

Formed through the accumulation and cementation of sand-sized mineral grains, primarily quartz. This specimen shows iron staining, suggesting formation in an oxidizing environment where iron-rich groundwater acted as a cementing agent.

Uses & Applications

Commonly used as a building material, in decorative masonry, as an abrasive, and as a reservoir rock for petroleum or groundwater.

Geological Facts

Sandstone accounts for about 20% of all sedimentary rocks on Earth. The famous red rock formations in Sedona, Arizona, and the Grand Canyon are primarily ferruginous sandstones.

Field Identification & Locations

Identify in the field by its sandpaper-like feel and visible grains. Often found in riverbeds, desert dunes, or coastal areas where ancient sand deposits have lithified.

Identified on: 4/22/2026

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