Limestone is a rock formed from varying amounts of flint, clay, sand, silt and calcite. Calcite in the limestone commonly originates from marine organisms but can also be present through groundwater that precipitated the material. Limestone makes up 10% of the total volume of sedimentary rock throughout the world.

Calcite can either be precipitated or dissolved by ground water depending on several environmental factors. Calcite can become less soluble as the water temperature increases -a peculiar characteristic. In the right conditions calcite form mineral coatings that glue the rock grains together or fill cracks and fractures in the stone.

Limestone Colouring

The varying colours prevalent in limestone derive from the impurities that are present, especially on weathered surfaces. These impurities can be clay, organic remains, sand and iron oxide. Formations of limestone can be crystalline, granular, clastic or massive and can be classified more precisely as Folk and Dunham.

Location of Limestone

Travertine is a variety of limestone found along the edges of water such as hot and cold springs, streams and waterfalls. Limestone can reform into marble during geographical shifts over time such as mountain building.

Limestone is susceptible to erosion and many eroded landforms such as caves, pot holes and gorges contain limestone. Limestone is more resistant then other sedimentary rocks and usually occurs amongst hills and downlands and typically amongst clay soils.

Limestone bands can form spectacular outcrops along the earth's surface and islands. Examples of huge limestone formations can be seen at County Clare in Ireland, Malham Cove in North Yorkshire and the Isle of White. Limestone is also prevalent in Sweden, The United States and Vietnam.

Uses of Limestone

Limestone is commonly used in architecture across the world in modern construction in Europe and North America and in many older landmarks such as the great pyramids in Egypt which are made entirely from Limestone. There is a city in Ontario, Canada that is nicknamed Limestone City because every building there is built from it. Limestone is relatively easy to work with and commonly available which is why it gets used extensively in construction despite the cost as limestone is an expensive material. Its weight can prevent it from being used to clad or construct particularly tall buildings.

Acid Rain and Limestone

Marble and limestone are susceptible to acid rain because of its porous qualities and this can be a huge problem for statues and buildings alike. When cleaning the stone a neutral or mild alkaline solution should be used at all times to prevent further erosion of the rock.