Fossiliferous Shale Matrix

Physical Properties

Hardness (Mohs scale): 3-5 overall, dark grey to black color, earthy to dull luster, layered/clastic structure, easy to scratch.

Formation & Geological History

Formed through the accumulation of fine-grained mud, silt, and clay mixed with organic debris and calcium carbonate shell fragments in a low-energy aquatic environment such as a lagoon or deep sea floor.

Uses & Applications

Primarily used for geological study, teaching paleontology, and as raw material for cement if found in large enough deposits; also popular for hobbyist fossil collecting.

Geological Facts

Black shale often indicates an anoxic (oxygen-poor) environment at the time of deposition, which is excellent for preserving biological structures that would otherwise rot.

Field Identification & Locations

Identify in the field by looking for distinct layers (fissility) and the presence of embedded white or grey calcified shapes which represent ancient marine life. Common near roadcuts in limestone-shale sequences.

Identified on: 4/27/2026

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