sedimentary

Fossiliferous Limestone

Bioclastic Limestone (composition: CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Tan, beige, and white; Luster: Dull/Earthy; Structure: Clastic/fragmental texture containing visible organic remains; Cleavage: None (fractures irregularly).

Hardness: 3 on Mohs scale
Color: Tan, beige, and white
Luster: Dull/Earthy

Identified March 23, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Tan, beige, and white; Luster: Dull/Earthy; Structure: Clastic/fragmental texture containing visible organic remains; Cleavage: None (fractures irregularly).

Formation & geological history

Formed in shallow, warm marine environments where calcium carbonate-rich skeletal remains (like shells and coral) accumulate and undergo lithification. Often dates from the Paleozoic or Mesozoic eras.

Uses & applications

Used in the production of cement, as a building stone (crushed or dimension stone), as a soil conditioner in agriculture, and for educational fossil collecting.

Geological facts

This specimen contains 'shell hash' or coquina-like fragments, which are the remains of ancient marine invertebrates such as brachiopods, bivalves, or gastropods. Limestone accounts for about 10% of the total volume of all sedimentary rocks.

Field identification & locations

Identify in the field by looking for visible shell impressions and testing with diluted hydrochloric acid; it will fizz (effervesce) vigorously. Commonly found in areas that were once prehistoric seabeds, such as the Midwestern US or the UK.