Sandstone (Ferruginous)

Physical Properties

Hardness: 6-7 (Mohs); Color: Brown, tan, reddish-brown; Luster: Dull/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 appears to have iron oxide (hematite/limonite) cement, giving it a rusty brown color. Formed in high-energy environments like rivers, deserts, or shorelines.

Uses & Applications

Commonly used as a building material, paving stones, and in the production of glass (if high silica). Poor quality fragments are used as road base or fill.

Geological Facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. It is a major reservoir for groundwater, oil, and natural gas due to its porosity/permeability.

Field Identification & Locations

Identify by its 'sandpaper' feel. It will scratch glass if it is quartz-based. Found globally in sedimentary basins. Look for bedding planes or layers in larger outcrops.

Identified on: 4/20/2026

Mode: Standard