Home » Rock Directory

Limestone

A common sedimentary rock consisting mostly of calcium carbonate, CaCO₃, used as a building stone and in the manufacture of lime, carbon dioxide, and cement. A sedimentary rock which, while relatively soft, weathers well. It has a very tight-grained appearance.

A SHORT HISTORY - LIMESTONE

Limestone is a type of sedimentary rock. It is chemically made up of the mineral calcite (calcium carbonate).

Limestone is formed by the deposition of calcium carbonate on the floors of water bodies.

Limestone is one the most widely known form of sedimentary rocks comprising about 10% of the sedimentary rocks. The colour of pure limestone is white or almost white. But you would find that various limestone's generally exhibit different colours because of the presence of impurities such as clay, sand, organic remains, iron oxides etc. It is more prominent on weathered surfaces. Limestone rocks are sedimentary rocks that are made from the mineral calcite which came from the beds of evaporated seas and lakes and from sea animal shells. This rock is used in concrete and is an excellent building stone for humid regions.

Limestones are also found in varied forms because of the difference in the way it has been formed. So, you may get limestone's that are crystalline, elastic, granular or dense.

Limestone finds wide-spread application in the construction sector. You would find it specially being used in architecture. Its ready availability and the versatility of the rock that allows it to be easily cut into blocks or more elaborate carvings make it very desirable for architects. It is also very durable and generally remains unaffected by exposure. The flip side is that it is very heavy and that's why it is practically not possible to use it in tall buildings. Its cost is another detrimental factor.

You would find that limestone used in humid climate remains unaffected, but it is very much vulnerable to acids. If a limestone structure is situated at a place where acid rain is frequent, you would find that the limestone undergoes heavy weathering destroying its beauty and shape.

The rock which contain more than 95% of calcium carbonate is known as high-calcium limestone. Recrystallised limestone takes good polish and is usually used as decorative and building stone.

A part of calcium molecules if being replaced by magnesium, it is known as magnesium lime stone or dolomite limestone.

Limestone that will take a polish are considered marbles by most people, but technically, if there are still shells visible or the structure is not crystalline, it is still a limestone.

[ Close ]