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Limestone is a sedimentary rock made up of calcite (CaCO3) as its main mineral. Some limestones were formed by chemical deposition and others by the accumulation of shells from minute sea creatures. Many invertebrate animals (animals with no backbones) take calcite from sea water to construct their shells. When they die the shells fall to the sea bed. Areas where there is little deposition of mud or sand will be ideal for the formation of limestone. One type of limestone which is very pure is called chalk, but most other limestones contain variable amounts of mud or sand or other material.
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Blake
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ReneLimestone caves are formed through a process called dissolution, where acidic water dissolves the calcium carbonate in the limestone rock over thousands of years. As the water seeps through cracks in the rock, it enlarges the passages and creates caverns. Over time, stalactites and stalagmites can form from mineral deposits left behind as the water evaporates.
Limestone dissolves under the action of rainwater and groundwater charged with H2CO3 (carbonic acid) and naturally occurring organic acids. The dissolution process produces a distinctive landform known as karst, characterized by sinkholes, sinking streams, and underground drainage. Limestone caves are often adorned with calcium carbonate formations produced through slow precipitation. These include: flowstones, stalactites, stalagmites, helictites, draperies, soda straws and columns. These secondary mineral deposits in caves are called speleothems.
The majority of limestone is thought to be formed by biogenic means. Microscopic organisms remove CO2 and Ca from seawater, convert the CO2 to the carbonate radical (CO3 2-) and form exoskeletons from the synthesized CaCO3. When the organisms die, these exoskeletons fall to the sea floor where they are preserved as limestone.
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How is moaning caverns formed?
It's a normal karst cave, but I think (from memory) in marble rather than unaltered limestone.
Which of these is the underwater buildup of limestone skeletons from certain small animals?
The correct term is "coral reef." Coral reefs are formed by the accumulation of calcium carbonate skeletons secreted by coral polyps over time.
What chemical test can be made to identify limestone?
One common chemical test to identify limestone is the acid test. Limestone will react with hydrochloric acid to produce bubbles of carbon dioxide gas. Another test involves applying a drop of dilute hydrochloric acid to the surface of the rock; if it fizzes, then it likely contains calcium carbonate, the main component of limestone.
What is Limestones melting point?
The melting point of limestone (calcium carbonate) is approximately 1,339 degrees Celsius (2,442 degrees Fahrenheit). At this temperature, limestone decomposes to form lime (calcium oxide) and carbon dioxide gas.
Is limestone with holes mechanical or chemical weathering?
Limestone with holes is typically a result of chemical weathering. The holes are often created through the process of carbonation, where carbonic acid in rainwater reacts with the calcium carbonate in limestone to dissolve it and create cavities over time.
