sedimentary
Fossiliferous Limestone
Calcium Carbonate (CaCO3) with Bioclastic inclusions
Hardness: 3-4 (Mohs scale); Color: Tan, beige, or light gray; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline calcite); Cleavage: None (conchoidal fracture); Specific gravity: 2.3-2.7
- Hardness
- 3-4 (Mohs scale)
- Color
- Tan, beige, or light gray
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-4 (Mohs scale); Color: Tan, beige, or light gray; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline calcite); Cleavage: None (conchoidal fracture); Specific gravity: 2.3-2.7
Formation & geological history
Formed in warm, shallow marine environments where skeletal fragments of marine organisms (like mollusks, corals, or crinoids) accumulate and are lithified over millions of years through compaction and cementation.
Uses & applications
Used as a primary source of lime for cement, as building stone, agricultural soil conditioner, and commonly collected as educational fossil specimens.
Geological facts
Much of the world's architectural limestone contains visible fossils that can be hundreds of millions of years old. The Great Pyramids of Giza were originally encased in white polished limestone.
Field identification & locations
Identify by looking for visible shell or organism imprints. It will react and fizz (effervesce) when in contact with dilute hydrochloric acid due to its calcium carbonate content.
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