sedimentary
Limestone with Fossil Inclusion
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: Gray to brownish-beige; Luster: Dull or earthy; Structure: Microcrystalline with visible porosity; Cleavage: None (conchoidal fracture).
- Hardness
- 3 on Mohs scale
- Color
- Gray to brownish-beige
- Luster
- Dull or earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Gray to brownish-beige; Luster: Dull or earthy; Structure: Microcrystalline with visible porosity; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed in shallow, warm marine environments through the accumulation of shell, coral, algal, and fecal debris. This specimen appears to contain a cylindrical fossil mold or cast, possibly a crinoid stem or burrow fragment.
Uses & applications
Used primarily in construction (aggregate, cement), agriculture (soil conditioner), and industrial chemical processes. Fossil-bearing specimens are valued for education and private collections.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. It is the primary rock type found in karst landscapes, leading to the formation of extensive cave systems.
Field identification & locations
Identify in the field by testing with a drop of cold 10% hydrochloric acid; it will effervesce (fizz) vigorously. Look for marine fossil imprints and a grainy or chalky texture.
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