Sandstone (Ferruginous)

Physical Properties

Hardness: 6-7 (Mohs scale); Color: Brown, tan, reddish (indicates iron content); 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 or rock fragments. These grains are typically quartz or feldspar. The brown/orange tint suggests it formed in an environment with high oxygen and iron-rich minerals (limonite/hematite staining).

Uses & Applications

Used widely in construction as a building material, for paving, and in the manufacturing of glass. In landscaping, it is used for decorative stones and retaining walls.

Geological Facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. The iconic 'Red Rocks' in the American Southwest and the ancient city of Petra are both famous examples of sandstone formations.

Field Identification & Locations

Identify in the field by its gritty, sandpaper-like texture and visible grains. It is commonly found in river beds, deserts, and coastal areas. For collectors, look for unique shapes or interesting banding (Liesegang rings).

Identified on: 4/19/2026

Mode: Standard