sedimentary

Fossiliferous Limestone

Biogenic Limestone (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs); Color: Pinkish-red to brownish matrix with white clasts; Luster: Dull to earthy; Structure: Fragmental/Clastic; Cleavage: None (conchoidal fracture).

Hardness: 3-4 (Mohs)
Color: Pinkish-red to brownish matrix with white clasts
Luster: Dull to earthy

Identified June 3, 2026More sedimentary →

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Physical properties

Hardness: 3-4 (Mohs); Color: Pinkish-red to brownish matrix with white clasts; Luster: Dull to earthy; Structure: Fragmental/Clastic; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed in warm, shallow marine environments from the accumulation of calcium carbonate and organic debris (shell/coral fragments). This specimen appears to contain crinoid or shell fragments in a hematite-stained calcitic matrix.

Uses & applications

Primarily used in construction (crushed stone, cement), architectural cladding, and as a decorative garden rock or collector's specimen.

Geological facts

The reddish color is often caused by trace amounts of iron oxide (hematite) during diagenesis. It acts as a biological record of ancient marine life.

Field identification & locations

Identify by testing for a reaction (fizzing) with dilute hydrochloric acid. Look for visible fossil fragments or bioclasts within the matrix. Commonly found in ancient inland sea beds.