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What is limestone?
Limestone is a sedimentary rock consisting mostly of calcium carbonate (CaCO3).
It is typically in the form of calcite or aragonite. Most limestones have
a granular texture with grains ranging in size from 0.00004 inch to visible
particles. The grains are likely to be tiny fragments of fossil animal shells.
Where does limestone come from?
Limestone has two origins:
- biogenic precipitation from sea water (autochthonous limestone), the primary
agents being lime-secreting organisms and foraminifera
- mechanical transport and deposition of preexisting limestones (allochthonous
limestone), forming clastic deposits.
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