Sandstone (Ferruginous)

Physical Properties

Hardness: 6-7 (if quartz-rich); Color: Tan, brown, or yellowish-orange due to iron oxides; Luster: Dull or earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.2-2.8

Formation & Geological History

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. This specific specimen suggests a river or beach environment where grains were lithified by iron-rich mineral cement over millions of years.

Uses & Applications

Commonly used as a building material, for paving stones, in glass manufacturing (if high purity quartz), and as a reservoir rock for oil and natural gas.

Geological Facts

Sandstone makes up about 20% of all sedimentary rocks on Earth. The vibrant colors in famous formations like the Grand Canyon or Antelope Canyon are largely due to different iron oxide levels in sandstone.

Field Identification & Locations

Identify in the field by its gritty, sand-like texture when rubbed and visible layers (bedding). It is found globally in deserts, riverbeds, and coastal regions. It often feels like sandpaper to the touch.

Identified on: 5/2/2026

Mode: Standard