Sandstone (Ferruginous)

Physical Properties

Hardness: 6-7 (Mohs scale); Color: Brown, tan, reddish-brown due to iron oxidation; Luster: Dull/Earthy; Crystal structure: Clastic texture; 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 rounded specimen indicates significant transport by water (river or beach) occurring over thousands to millions of years.

Uses & Applications

Commonly used as a building material, paving stones, and in glass manufacturing if silica content is high. In this rounded form, it is often used for landscaping or as decorative 'river rock'.

Geological Facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. The iron oxide (hematite or limonite) acting as a partial cement gives this specimen its distinctive brown color.

Field Identification & Locations

Identify by its 'sandpaper' feel and visible grains under a hand lens. Commonly found in riverbeds, canyons, and coastal areas. It will not fizz with HCl unless it has a calcite cement.

Identified on: 4/18/2026

Mode: Standard