Fossiliferous Limestone

Physical Properties

Hardness: 3 on Mohs scale; Color: Gray to light tan; Luster: Dull/Earthy; Structure: Clastic or non-clastic containing visible brachiopod and bivalve imprints; Cleavage: None (fractures roughly).

Formation & Geological History

Formed in shallow, calm marine environments where organic remains (shells, coral) accumulated over millions of years and were lithified. These specimens are often from the Paleozoic or Mesozoic eras.

Uses & Applications

Used primarily in construction (aggregate, cement), as floor tiles, for agricultural lime, and as educational or decorative specimens for fossil collectors.

Geological Facts

This specimen contains a high density of brachiopods, which are ancient marine organisms that look like clams but are biologically distinct. Most limestone on Earth was created by biological processes.

Field Identification & Locations

Identify in the field by looking for visible shell imprints or rib patterns. It will react and fizz (effervesce) if a small drop of diluted hydrochloric acid or strong vinegar is applied. Commonly found in road cuts or creek beds in historically marine regions.

Identified on: 4/17/2026

Mode: Standard