sedimentary
Limestone with Fossil Inclusion
Sedimentary Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs scale); Color: Gray to brownish; Luster: Dull/Earthy; Structure: Massive with organic textures; Cleavage: None; Specific Gravity: 2.5-2.7
- Hardness
- 3 (Mohs scale)
- Color
- Gray to brownish
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3 (Mohs scale); Color: Gray to brownish; Luster: Dull/Earthy; Structure: Massive with organic textures; Cleavage: None; Specific Gravity: 2.5-2.7
Formation & geological history
Formed in marine environments from the accumulation of shell, coral, algal, and fecal debris. These rocks often date from the Paleozoic to the Cenozoic era, formed by chemical precipitation or organic accumulation.
Uses & applications
Large scale use in construction as aggregate, cement production, soil conditioner in agriculture, and small specimens are collected for paleontological study.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. Many famous caves, such as Mammoth Cave, are carved out of limestone.
Field identification & locations
Identify by its reaction (fizzing) with dilute hydrochloric acid. Commonly found in areas that were once prehistoric seafloors. Collectors look for visible fossil impressions or crystal pockets.
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