What is Limestone?

Saint Patrick's Basilica, in Fremantle, Western Australia, is constructed from limestone, a sedimentary rock with many uses in daily human life and natural ecosystems.
Saint Patrick's Basilica, in Fremantle, Western Australia, is constructed from limestone, a sedimentary rock with many uses in daily human life and natural ecosystems.

5. Description

There are a variety of types of limestone available, each with their own unique looks and use. Generally, however, most typically come in small, clastic (although some are non-clastic), hard rock formations. The color of limestone varies from rock to rock, though most are light in color, and usually having hints or grey or yellow. Limestone is a sedimentary rock, although it has a hardness of 3-4 Mohs and a density of 2.5 to 2.7 grams per cubic centimeter. The rock is primarily composed of calcite or calcium carbonate, with most of these rocks being around 95% calcium carbonate. Being so high in calcium makes limestone rock polish and smooth better.

4. Location

Limestone forms in various ways, most commonly forming in shallow, calm, and warm marine waters. These buildups of limestone can be found between 30 degrees North Latitude and 30 degrees South Latitude of the globe. Such deposits are found in the Caribbean Sea, the Indian Ocean, the Persian Gulf, and the Gulf of Mexico. Another way limestone forms is through evaporation, with this type of limestone growing in caves around the world. China, the US, Russia, Japan, India, Brazil, Germany, Mexico, and Italy are some of the world's largest limestone prouducers today. Some of the biggest quarries in the world, however, are in the U.S. state of Michigan, specifically near the Great Lakes' coastlines.

3. Formation

When limestone forms in water, the rock becomes a collection of calcium carbonate shells and skeletons from previous lifeforms who have died on the ocean floor, and are mixed up with other rock sediments over time. This enables the rock to accumulate debris which includes said shells and skeletons, and eventually this causes a buildup of calcium carbonate. Another formation process of Limestone occurs through evaporation. In this manner, droplets on cave walls seep down from the entrances of the cave through fractures, and this water then evaporates, leaving a calcium carbonate deposit behind, which forms limestone.

2. Uses

Limestone is a widely used product. Whether it be for gardening, for building a structure, or for cleaning the outside of your home, limestone probably has a useful purpose for you. Quicklime and Slaked lime sourced from limestone are used to neutralize acidity that is caused by acidic precipitation in soils and lakes. Due to limestone's amazing glossy appearance when polished, it is a popular decorative building material, such as for countertops and flooring. Limestone is also used to purify iron in blast furnaces and used as a material in concrete and mortar, as well as in the making of certain types of glass.

1. Production

The mining of limestone begins with its extraction from deposits in mines and quarries, with many of these mines being located in the United States, as well as in parts of the African and South American continents. After extraction, limestone is tested for its chemical composition. Limestone that meets the required calcium carbonate levels is then put into a “lime kiln”, and heated to 1000 degrees Celsius (1,832o Fahrenheit). Depending on the type of limestone begin produced, it may be hydrated by adding water to its composition, which is how we quicklime and slaked lime are formed.


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