Fossiliferous Shale (with Vertebrate Bones)

Physical Properties

Gray to brown matrix color, dull/earthy luster, fine-grained texture (clastic), includes dark blue-black permineralized bone fragments. Matrix Mohs hardness: 3; Fossil hardness: 5.

Formation & Geological History

Formed in a low-energy depositional environment such as a lake bed, river floodplain, or shallow sea. Geological age varies by site, often Cretaceous to Eocene.

Uses & Applications

Primary use is scientific study (paleontology) and private collection. Not used in industry or construction due to fragility.

Geological Facts

The dark blue or black coloration in the fossilized bone is often a result of permineralization with iron or phosphate minerals. These specimens help reconstruct prehistoric ecosystems.

Field Identification & Locations

Identify in the field by looking for distinct smooth, porous textures (bone structure) or dark glassy fragments embedded in fine-grained layered rock. Commonly found in 'Badlands' topography.

Identified on: 4/21/2026

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