Sandstone (Red Sandstone)

Physical Properties

Hardness: 6-7 (individual grains), rock overall is friable. Color: Red, pink, or brownish-red. Luster: Dull/Earthy. Crystal structure: Granular/Clastic. Cleavage: None. Specific gravity: 2.2-2.8.

Formation & Geological History

Formed by the accumulation of sand-sized mineral grains or rock fragments (0.0625 to 2 mm) that are lithified over time. Red color is due to iron oxide (hematite) coating the grains, often in arid terrestrial environments.

Uses & Applications

Used extensively as a building material, paving stone, decorative architectural elements, and as a reservoir rock for oil, gas, and groundwater.

Geological Facts

Sandstone accounts for roughly 20 to 25 percent of all sedimentary rocks on Earth. Famous landmarks like the Treasury at Petra and the Grand Canyon are primarily composed of various sandstone layers.

Field Identification & Locations

Identify by its gritty texture (feels like sandpaper) and visible sand grains. Found globally in deserts, river basins, and coastal areas. Collectors should look for unique cross-bedding patterns or fossil inclusions.

Identified on: 4/19/2026

Mode: Standard