Fossiliferous Limestone

Physical Properties

Hardness: 3-4 (Mohs), Color: light gray to tan, Luster: dull to earthy, Composition: primarily calcium carbonate (calcite) with embedded fossil fragments.

Formation & Geological History

Formed in shallow marine environments where organic debris, such as shells and coral fragments, accumulated and lithified over millions of years.

Uses & Applications

Used in construction, as a building stone, in the manufacture of cement, and as a soil conditioner in agriculture. Also valued by collectors for the fossils it contains.

Geological Facts

Fossiliferous limestone often provides important clues about past marine environments and the organisms that lived there. The visible structures often include pieces of crinoids, brachiopods, or bivalves.

Field Identification & Locations

Identify by its light color, relatively soft nature (scratched by a knife), and the presence of visible fossil fragments. It typically reacts (fizzes) with dilute hydrochloric acid. Commonly found in regions that were once covered by shallow, warm seas.

Identified on: 4/26/2026

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