sedimentary
Fossiliferous Limestone
Calcium Carbonate (CaCO3) with fossil inclusions
Hardness: 3 (Mohs scale), Color: Creamy white to brownish-gray, Luster: Dull to earthy, Structure: Fine-grained matrix with embedded fossil cavities, Cleavage: None (conchoidal to irregular fracture)
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Physical properties
Hardness: 3 (Mohs scale), Color: Creamy white to brownish-gray, Luster: Dull to earthy, Structure: Fine-grained matrix with embedded fossil cavities, Cleavage: None (conchoidal to irregular fracture)
Formation & geological history
Formed in warm, shallow marine environments from the accumulation of calcium carbonate and organic debris (shells/corals) over millions of years, typically Paleozoic to Mesozoic era.
Uses & applications
Used in construction as aggregate, in the production of lime and cement, for soil neutralization in agriculture, and as decorative stone.
Geological facts
This specimen contains 'external molds' or 'casts' of ancient marine life, likely crinoids or small brachiopods, which have weathered out to leave circular depressions.
Field identification & locations
Look for a reaction (fizzing) when exposed to weak acid like vinegar; often found in outcrops of ancient seabed. Commonly found in the Midwestern USA and UK limestone belts.
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