Stalactite
A stalactite , of the Greek stalaktos (who runs drop by drop) is a calcareous concretion which is formed with the vault of the caves and undergrounds, or under ceilings or flagstones of concrete of bad quality or split; the stalactites are for example common in the Blockhaus of the First World War or the Second world war. With the stalagmites and other concretions of caves, they form the group of the spéléothèmes .
Elles is formed by crystallization with the air of the salts (essentiellemnet of salts limestones) dissolved by water in the rock (or in the concrete). They generally settle on the vaults, and sometimes in lines while following cracks or microphone-faults or the zones of more permeable rocks. In moderated zone, they can sometimes be marked by annual rings.
They can be coloured by the metal salts dissolved by water in the rock (oxides iron, coppers, manganese, etc)
They are formed at very variable speeds (of a few centimetres per annum to less than one millimetre per millenium, according to the content of water rock salt, according to the flow of water and the speed of evaporation or the presence of bacteria in a Biofilm which can accelerate the phenomenon of crystallization.
If, by the fall as of this water, concretion is formed on the ground, it takes the name of Stalagmite . Quelquesfois, the ones and the others meet and form columns which grow bigger gradually and end up filling the cavities which contain them.
In Architecture, it is a decorative reason which points out the shape of the natural stalactites.
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