sedimentary
Limestone Riprap
Sedimentary Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale), Color: light gray to white, Luster: dull/earthy, Crystal structure: Trigonal (microcrystalline), Cleavage: none in bulk rock
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Physical properties
Hardness: 3-4 (Mohs scale), Color: light gray to white, Luster: dull/earthy, Crystal structure: Trigonal (microcrystalline), Cleavage: none in bulk rock
Formation & geological history
Formed primarily from the accumulation of shell, coral, algal, and fecal debris in clear, warm, shallow marine waters over millions of years. These specimens appear to be mechanically crushed from a quarry.
Uses & applications
Used extensively in civil engineering for erosion control (riprap), road base construction, concrete aggregate, and as a livestock mineral supplement.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. It is often the primary source of lime for cement production and can contain significant fossil remains.
Field identification & locations
Identify by its light gray color, fine-grained texture, and its reaction (fizzing) when exposed to dilute hydrochloric acid. Commonly found in former marine basins and used along shorelines and riverbanks.
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