sedimentary
Fossiliferous Limestone
Calcium Carbonate (CaCO3) with fossil inclusions
Hardness: 3 on Mohs scale; Color: Gray to tan; Luster: Dull or earthy; Crystal structure: Trigonal (calcite matrix); Cleavage: Perfect rhombohedral in calcite crystals but often massed; Specific gravity: 2.7.
- Hardness
- 3 on Mohs scale
- Color
- Gray to tan
- Luster
- Dull or earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Gray to tan; Luster: Dull or earthy; Crystal structure: Trigonal (calcite matrix); Cleavage: Perfect rhombohedral in calcite crystals but often massed; Specific gravity: 2.7.
Formation & geological history
Formed in marine environments through the accumulation of organic debris such as shell, coral, and algal fragments over millions of years, typically during the Paleozoic or Mesozoic eras.
Uses & applications
Used in construction, as a building stone (dimension stone), in the production of lime and cement, as an abrasive, and small fossil specimens are popular for educational purposes and hobbyist collecting.
Geological facts
This specimen contains visible fossilized remains, likely brachiopods or crinoids. Limestone makes up about 10 percent of the total volume of all sedimentary rocks on Earth.
Field identification & locations
Identify in the field by looking for visible shell fragments and testing with a drop of cold dilute hydrochloric acid (it will fizz). Commonly found in areas that were once prehistoric seafloors.
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