sedimentary
Fossiliferous Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs scale); Color: Gray to off-white; Luster: Dull to earthy; Crystal structure: Trigonal/Microcrystalline; Cleavage: Perfect rhombohedral in calcite crystals, though often obscured in rock form.
- Hardness
- 3 (Mohs scale)
- Color
- Gray to off-white
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 (Mohs scale); Color: Gray to off-white; Luster: Dull to earthy; Crystal structure: Trigonal/Microcrystalline; Cleavage: Perfect rhombohedral in calcite crystals, though often obscured in rock form.
Formation & geological history
Formed in marine environments from the accumulation of organic debris such as shell, coral, and algal material, cemented by calcium carbonate over millions of years.
Uses & applications
Used primarily in construction for building stone, road base, and as an ingredient in cement. Small fossil-rich specimens are popular for educational purposes and entry-level collecting.
Geological facts
This specimen contains visible fossil fragments, likely crinoids or shell pieces, common in Paleozoic limestone layers. Limestones form more than 10% of the total volume of all sedimentary rocks.
Field identification & locations
Identified by its gray color and the presence of organic prehistoric structures. It will react and fizz (effervesce) if touched with a weak acid like vinegar due to the presence of calcite.
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