sedimentary

Shale (with Iron Oxide staining)

Fissile Mudstone (primarily Quartz and Clay minerals)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Gray to black with red/brown iron staining; Luster: Dull/Earthy; Structure: Fine-grained, clastic; Cleavage: High fissility (splits into thin layers); Specific Gravity: 2.4-2.8

Hardness: 3 on Mohs scale
Color: Gray to black with red/brown iron staining
Luster: Dull/Earthy

Identified March 30, 2026More sedimentary →

Explore Shale (with Iron Oxide staining) 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 compaction of silt and clay-size mineral particles. These sediments are typically deposited in low-energy environments like lake bottoms, river deltas, or floodplains. Age varies widely from Precambrian to Cenozoic based on location.

Uses & applications

Used as a source of clay for ceramics and bricks, a filler in paints and plastics, and as a raw material in Portland cement. It is also significant in the energy industry as a source rock for natural gas and oil.

Geological facts

Shale is the most common sedimentary rock on Earth, making up approximately 70% of the rocks in the Earth's crust. It often preserves fossils more effectively than coarser-grained sedimentary rocks.

Field identification & locations

Identify in the field by its ability to split into thin, flat plates (fissility) and its soft, fine-textured feel. It is commonly found in sedimentary basins and outcrops near water bodies. Collectors should look for impressions of leaves or small shells within the layers.