Shale

Physical Properties

Hardness 3 (Mohs scale), dark gray to black, dull or earthy luster, layered/fissile structure, smooth texture when split along planes.

Formation & Geological History

Formed from the compaction of silt and clay-sized mineral particles, typically in low-energy environments like lake beds or deep ocean basins.

Uses & Applications

Raw material for the production of brick, tile, and pottery; important source rock for natural gas and petroleum.

Geological Facts

Shale is more common than all other types of sedimentary rocks combined. It often contains well-preserved fossils due to the fine-grained nature of the sediment.

Field Identification & Locations

Identify in the field by its thin layers (fissility) and tendency to break into thin, flat fragments. Common in sedimentary basins worldwide.

Identified on: 5/7/2026

Mode: Standard