sedimentary

Fossiliferous Limestone

Biogenic Sedimentary Rock (Calcium Carbonate, CaCO3)

Hardness: 3 on the Mohs scale; Color: Tan, grey, brown, or yellowish; Luster: Dull to earthy; Crystal structure: Trigonal (calcite); Cleavage: Perfect rhombohedral in calcite crystals; Specific Gravity: 2.7 to 2.9.

Hardness: 3 on the Mohs scale
Color: Tan, grey, brown, or yellowish
Luster: Dull to earthy

Identified August 2, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow, warm marine environments where organisms such as brachiopods, crinoids, bryozoans, and mollusks accumulate and become cemented together by calcium carbonate over millions of years.

Uses & applications

Used in the construction industry as crushed stone for road base, building material, and in the manufacturing of cement and lime; also valued by fossil collectors.

Geological facts

Fossiliferous limestone often contains a rich record of ancient marine biodiversity, allowing geologists to reconstruct paleoenvironments from hundreds of millions of years ago.

Field identification & locations

Easily identified in the field by applying a drop of dilute hydrochloric acid, which will cause it to fizz vigorously due to the release of carbon dioxide, and by visually spotting embedded fossil fragments.

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Sandstone or Siltstone

Arenite (if sandstone)

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Fossiliferous Concretion

Septarian Concretion containing Brachiopods/Crinoids

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Quartz pebble

Silicon dioxide (SiO2)

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Generic Pebble / Rock Fragment

Lithic fragment / Weathered rock

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Sedimentary Sandstone

Arenite (Sedimentary Rock)

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Banded Siltstone / Mudstone Pebble

Siltstone / Argillite

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