sedimentary
Fossiliferous Limestone
Calcium Carbonate (CaCO3) with Bioclastic Inclusions
Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull/Earthy; Crystal Structure: Rhombohedral (microcrystalline matrix); Cleavage: Perfect rhombohedral in calcite crystals; Specific Gravity: 2.7
- Hardness
- 3 on Mohs scale
- Color
- Gray, tan, or white
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull/Earthy; Crystal Structure: Rhombohedral (microcrystalline matrix); Cleavage: Perfect rhombohedral in calcite crystals; Specific Gravity: 2.7
Formation & geological history
Formed in warm, shallow marine environments by the accumulation of organic debris such as shell, coral, algal, and fecal debris. Typically Paleozoic to Cenozoic in age.
Uses & applications
Used primarily in the construction industry as building stone, aggregate for concrete, and lime production. It is also used as a soil conditioner and a base for toothpaste.
Geological facts
Many of the world's most famous caves, including Mammoth Cave in Kentucky, are formed in thick layers of limestone. This rock essentially represents ancient sea floors preserved for millions of years.
Field identification & locations
Identify in the field by checking for biological imprints (fossils) and its reaction to dilute hydrochloric acid (it will fizz). Commonly found in areas that were once prehistoric coastlines.
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