sedimentary

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Tan, beige, grey, or yellow-brown; Luster: Dull/Earthy; Structure: Clastic or crystalline matrix with visible fossil inclusions; Reaction: Effervesces strongly with dilute hydrochloric acid.

Hardness: 3 on Mohs scale
Color: Tan, beige, grey, or yellow-brown
Luster: Dull/Earthy

Identified April 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow, calm, warm marine waters from the accumulation of shell, coral, algal, and fecal debris. These sediments are lithified over millions of years through compaction and cementation.

Uses & applications

Used primarily in the construction industry as building stone, agricultural lime, and a component of cement. High-quality slabs are used for architectural cladding and floor tiles.

Geological facts

This rock acts as a biological record of ancient marine life. Many of the visible fragments are likely from brachiopods, crinoids, 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 fossil fragments and testing with acid (it will fizz). Commonly found in areas that were once ancient sea beds, such as the midwestern United States and southern England.