Earth

Rocks that are most suited

Calcite and dolomite (calcium carbonate and calcium carbonate and magnesium, respectively) are minerals that are very abundant on the Earth’s surface and are the main constituents of particular sedimentary rocks, known as carbonatic rocks, such as limestone and dolomite rocks. These rocks are not the most prone to karstification (gypsum and rock salt are much more soluble), however they are the most common rocks in which karstification processes take place, the most widespread and the ones able to support the existence of large volume rooms and galleries without collapsing, unlike other "weaker" rocks. For this reason the longest and deepest caves on the planet are to be found in this type of rocks. (In dolomite rocks, that are actually as soluble as calcite, the dissolving reaction is much slower and as a residue of the reaction, the rock tends to produce a sand that fills the fissures where water circulates, and this finally slows karstification down. Therefore karstification in dolomite rocks is a much less important process than in limestone rocks).