sedimentary

Red Shale

Lutite (primarily composed of Hydrous Aluminum Silicates with Hematite staining)

AI-generated identification · may be incorrect

Hardness: 3 (Mohs scale); Color: Reddish-brown to brick red; Luster: Dull/Earthy; Crystal Structure: Clastic (fine-grained clay minerals); Cleavage: Perfect fissility (breaks into thin layers); Specific Gravity: 2.4-2.8

Hardness: 3 (Mohs scale)
Color: Reddish-brown to brick red
Luster: Dull/Earthy

Identified March 30, 2026More sedimentary →

Explore Red Shale in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed through the lithification of mud and clay particles deposited in calm, oxygen-rich environments like river floodplains or shallow marine basins. The red color indicates the presence of ferric iron (hematite) during formation. Most common in Paleozoic and Mesozoic strata.

Uses & applications

Used primarily in the manufacturing of bricks, terracotta, and cement. It is also processed as a filler in various industrial compounds and used for road base in local construction.

Geological facts

Red shale is a key indicator of terrestrial or shallow-water oxygenated environments. Because it splits so thinly, it is a common host rock for fossilized leaves and insect remains.

Field identification & locations

Identify in the field by its distinct layering (fissility) and soft, earthy texture that can often be scratched with a fingernail. It is common throughout the Appalachian Mountains and the Colorado Plateau. Collectors look for pieces containing fossil impressions.