Sandstone (Ferruginous)

Physical Properties

Hardness: 6-7 (Mohs scale for grains); Color: Tan, yellow, brownish-orange; 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, primarily quartz. The brownish-yellow color suggests iron oxide (limonite or hematite) acting as a cementing agent. These rocks can form in deserts, riverbeds, or marine environments over millions of years.

Uses & Applications

Used widely in construction (building stone, paving), glass manufacturing (if high silica), and as a reservoir rock for oil and natural gas.

Geological Facts

Sandstone constitutes about 20-25% of all sedimentary rocks on Earth. The famous red rock formations in Sedona, Arizona, and the Grand Canyon are primarily types of sandstone colored by iron oxidation.

Field Identification & Locations

Identify in the field by its gritty, sandpaper-like texture and visible sand grains. It usually feels rough to the touch and can be scratched with a steel blade depending on the strength of the cement. Found globally in basins and coastal regions.

Identified on: 4/16/2026

Mode: Standard