sedimentary

Eurasite (or Ferruginous Sandstone)

Ferruginous Sandstone (SiO2 with Fe2O3/FeOOH)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs); Color: Dark brown, reddish-brown, ochre; Luster: Dull/Earthy; Crystal Structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.5-3.0

Hardness: 6-7 (Mohs)
Color: Dark brown, reddish-brown, ochre
Luster: Dull/Earthy

Identified June 12, 2026More sedimentary →

Explore Eurasite (or Ferruginous Sandstone) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6-7 (Mohs); Color: Dark brown, reddish-brown, ochre; Luster: Dull/Earthy; Crystal Structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.5-3.0

Formation & geological history

Formed through the cementation of quartz grains where iron oxides (hematite or goethite) act as the binding agent. The iron often leaches from surrounding soils into groundwater, precipitating in porous sand layers over millions of years.

Uses & applications

Primarily used as a minor building stone, decorative landscaping rock, and occasionally as a source of low-grade iron ore. In some regions, historical buildings were constructed from it due to its accessibility.

Geological facts

This specimen shows significant water-rolling or river tumbled wear, giving it a characteristic bread-loaf or bar shape. The dark, glossy 'patina' on the top surface is likely a desert varnish or water-deposited manganese/iron coating.

Field identification & locations

Identify in the field by its grainy sand-like texture, heavy weight compared to pure quartz, and reddish-brown streak. Often found in ancient riverbeds, coastal regions, and arid environments.