sedimentary

Ferruginous Sandstone (River Pebble)

Clastic Sedimentary Rock (primarily SiO2 with Fe2O3 cement)

AI-generated identification · may be incorrect

Hardness: 6-7 (on Mohs scale); Color: Reddish-brown to tan; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific gravity: 2.3-2.6

Hardness: 6-7 (on Mohs scale)
Color: Reddish-brown to tan
Luster: Dull/Earthy

Identified March 16, 2026More sedimentary →

Explore Ferruginous Sandstone (River Pebble) 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 (on Mohs scale); Color: Reddish-brown to tan; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific gravity: 2.3-2.6

Formation & geological history

Formed through the lithification of sand-sized grains, typically quartz. Its reddish color comes from iron oxide (hematite) cementing the grains together. This specimen has been rounded by fluvial (river) or glacial transport over thousands of years.

Uses & applications

Common varieties are used as construction aggregate, road base, and in decorative landscaping. This specific polished pebble has low industrial but high personal/educational value.

Geological facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth and is a primary reservoir for ground water and oil because of its porosity and permeability.

Field identification & locations

Identify in the field by its gritty 'sandpaper' texture and visible mineral grains. It is commonly found in riverbeds and coastal areas where ancient sedimentary layers have eroded.