sedimentary
Fossiliferous Limestone
Calcium carbonate (CaCO3) with marine fossils
Hardness: 3 on Mohs scale; Color: Grey, tan, or white; Luster: Dull to earthy; Crystal structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral in calcite crystals; Specific gravity: 2.7.
- Hardness
- 3 on Mohs scale
- Color
- Grey, tan, or white
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Grey, tan, or white; Luster: Dull to earthy; Crystal structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral in calcite crystals; Specific gravity: 2.7.
Formation & geological history
Formed in warm, shallow marine environments through the accumulation of shell, coral, algal, and fecal debris over millions of years (Paleozoic to Cenozoic eras).
Uses & applications
Used in construction as a building material, aggregate for roads, production of cement/lime, and by collectors for the fossils it contains.
Geological facts
The Great Pyramids of Giza are mostly constructed from fossiliferous limestone. This specific specimen contains visible remnants of ancient marine organisms like crinoids or bryozoans.
Field identification & locations
Identify in the field by looking for visible shell fragments or fossils. It will react and fizz (effervesce) when a drop of cold dilute hydrochloric acid (or vinegar) is applied.
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