Limestone, dolomite, marble, chalk, plaster and salt – where these soluble breeds lie, are formed the karst caves which are washed away by water. In them it is possible to see hanging down from "ceiling" and speakers from "floor" mineral outgrowths are stalactites and stalagmites.
These terms are entered into literature by the Danish naturalist Ole Worm in 1655. Stalactites (from Greek stalaktites – "accumulated on a drop") are natechno-drop formations, most often calcite (CaCO3), the caves which are hanging down from a ceiling. They can have the conical or cylindrical shape. Rain water filters through the cave arch, dissolves in itself the limestone which is contained in rock and slowly drips from "ceiling". At the same time a part of water evaporates, and the limestone dissolved in it crystallizes anew in the form of stone "icicles". Stalactites are so formed. Formations can have also the form of "straws", "fringes", "combs" and others. Length of stalactites in some cases reaches several meters. The drops of lime water which fell down also evaporate, and the dissolved limestone remains in the place of falling of drops. Stalagmites (from Greek stalagmites - "drop") are the "turned" natechno-drop formations growing in a type of cones from a bottom of caves and other karst cavities. The highest stalagmite in the world found in a cave Las Williams (Cuba) has height of 63 meters. Dissolution of water in limestone happens on chemical reaction: CaCO3 + H2O + CO2 <=> Ca(2+) + 2 HCO3 (-). When reaction goes in the opposite direction (under certain conditions), salt deposits are formed. Sedimentation and bilateral growth of calcareous "icicles" lasts for centuries and in the millennia. Rising towards to stalactites, stalagmites quite often grow together with them and form the stalagnata having an appearance of kolonnopodobny formations. In this case all space of a karst cave can be covered with mineral columns of a bizzare shape.