What is Limestone?
Limestone, is a sedimentary rock that consists of the minerals calcite and aragonite. Limestone is also composed of skeletal from marine organisms. Types of organisms that may be found are coral or foraminifera. The volume of all sedimentary rocks makes up to 10 percent of limestone. Cave systems are mostly through limestone bed rock. Limestone is used in mostly everything some may not realize. It is used as a building material, base material for roads, white pigment or filler in toothpaste or paints, and as a chemical feedstock.
Limestone is mostly composed of grains including marine organisms. Other grains that are found in limestone are ooids, peloids, intraclasts, and extraclasts. The organisms listed secrete shells that are made up of aragonite or calcite, and leave the shells behind after the organism dies. Limestone contains certain amounts of silica that is in the form of chert or siliceous skeletal fragments. Clay, silt and sand are also found in limestone. These minerals are carried in the river where organisms may live. There is another type of limestone that does not contain any grain, in fact is made up of chemical precipitation of calcite, or travertine. This can be seen in its appearance which can be slightly granular. Some organisms may be made up of rock, also known as reefs. Typically limestone does not form in deep waters due to the dissolution of calcite. It dissolves from water pressure and temperature conditions. Depending on the type of surface it affects the color of the limestone. The color changes because of the impurities clay, sand, organic remains, iron oxide, and other materials may produce. Depending on how it’s formed, limestone may be crystalline, or clastic.
There are two different types of classifications that identify limestone and carbonate rock. Folk classification states that, based on how the rock is composed of three main components which are allochems, matrix, and cement. Another classification group is Dunham classification. This mainly focuses on the texture. The name that the limestone is given is determined upon the texture of the stone. Dunham categorizes the rock in four main groups. This is based off the coarser clastic particles. He focuses on whether or not the grains were originally contacted, or if they rock is characterized by the way frame builders made them.
Limestone is very useful to builders and consumers as well. It can be found in architecture in Europe and North America. One famous monument is the Great Pyramid, located in Egypt. Buildings in Kingston, Ontario, Canada are made of limestone which gives them the name ‘Limestone City’. Malta also has different types of limestone called Globigerina. For a while it was only available as a building material, and is still used for all buildings and sculptures. It is easy to cut into block, and can hold exposure well. Since it is so heavy it is not ideal for tall buildings, and is expensive as well. Parts of the United States contain limestone. Indiana is popular in high quality quarried limestone also known as Indiana limestone. Limestone was very popular in the middle ages because it was hard, durable, and easily accessible surface exposures. Limestone therefore cannot stand the harsh reaction to acid rain which may cause damage to the color and presence.