Limestone rocks in the form of a karst

Cotswold stone cottages in Bibury, England. They were built in 1380 as a monastic wool store and converted into weavers' cottages in the 17th century

Limestone is a Sedimentary rock, made up mostly of the minerals calcite and aragonite, two forms of calcium carbonate, CaCO₃.

The calcium carbonate is originally produced by living organisms. Later, some of it goes into solution in sea water. Limestone rocks include mainly organic remains and rock.

Limestone is about 10% of the total volume of all sedimentary rocks.