sedimentary
Fossiliferous Limestone
Bioclastic Limestone (composition: CaCO3)
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
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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.
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