sedimentary
Fossiliferous Limestone
Sedimentary Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs scale); Color: Gray to off-white/beige; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: None/conchoidal; Specific gravity: 2.3-2.7
- Hardness
- 3 (Mohs scale)
- Color
- Gray to off-white/beige
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 (Mohs scale); Color: Gray to off-white/beige; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Cleavage: None/conchoidal; Specific gravity: 2.3-2.7
Formation & geological history
Formed in shallow, calm, warm marine waters from the accumulation of shell, coral, algal, and fecal debris. These biological sediments undergo lithification over millions of years (often Paleozoic to Mesozoic era).
Uses & applications
Used in construction as building stone, road base, and an ingredient in Portland cement. Also used in agriculture to neutralize soil acidity and as a decorative stone in landscaping.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It often contains visible fossils of ancient marine organisms and is the primary rock type found in Karst topography, leading to the formation of extensive cave systems.
Field identification & locations
Identify in the field by its light appearance and the presence of small fossil fragments. It can be confirmed by a positive acid test (fizzes when exposed to weak hydrochloric acid or vinegar). Commonly found in areas that were once prehistoric seafloors.
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