sedimentary
Fossiliferous Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
Hardness: 3 (Mohs scale); Color: Dark gray matrix with light tan or cream fossil inclusions; Luster: Dull/Earthy; Structure: Clastic or Biogenic; Cleavage: None (conchoidal or irregular fracture).
- Hardness
- 3 (Mohs scale)
- Color
- Dark gray matrix with light tan or cream fossil inclusions
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3 (Mohs scale); Color: Dark gray matrix with light tan or cream fossil inclusions; Luster: Dull/Earthy; Structure: Clastic or Biogenic; Cleavage: None (conchoidal or irregular fracture).
Formation & geological history
Formed in shallow, warm marine environments where biological debris like shell fragments, coral, or microscopic organisms accumulate and are lithified over millions of years. This specimen likely dates from the Paleozoic or Mesozoic eras.
Uses & applications
Commonly used in the production of cement, as road aggregate, in agricultural lime to neutralize soil acidity, and as a decorative building stone. Fossiliferous specimens are also popular for educational purposes and novice collecting.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It often contains perfectly preserved fossils of ancient sea creatures like brachiopods, crinoids, or bivalves.
Field identification & locations
Identified in the field by its characteristic gray color and the presence of visible fossil remains. It will react and fizz (effervesce) if a weak acid like vinegar is applied. Found globally in areas that were once prehistoric seabeds.
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