Kalkstein

Kalkstein, or limestone, is a sedimentary rock composed mainly of calcium carbonate (CaCO3). It forms predominantly from the accumulation of shells, corals, algae and other remains of marine organisms, as well as from chemical precipitation of calcium carbonate in shallow seas and caves. The primary mineral is calcite, with impurities such as clay, silt, quartz and organic matter.

Limestone occurs in many geological settings, including ancient reefal buildups and mudstones, and in varieties such as fossiliferous limestone, micrite, oolitic limestone, and chalk. Travertine forms by rapid precipitation of calcium carbonate in caves and near hot springs. Marble, a metamorphic rock, can derive from limestone through recrystallization under heat and pressure, while karst processes weather and dissolves limestone to create caves, sinkholes and complex underground drainage systems.

Limestone beds are widespread worldwide and serve as important aquifers and reservoir rocks in some basins. It is a key source of calcium carbonate for industrial uses, and its dissolution shapes many landscapes, including karst topographies and cave systems. The mineral’s formation and alteration are influenced by climatic, biological and chemical factors over geological time.

Uses and significance include construction material for buildings and monuments, crushed stone for roads and concrete, and lime production through calcination, which yields quicklime and slaked lime for cement, agriculture and chemical industries. Quarrying and processing of Kalkstein have economic value but can impact ecosystems, and cement production involving calcination releases significant CO2 emissions.