Defying Gravity

Arguably the most enigmatic and fascinating type of speleothem are the helictites, or Excentriques, as the French aptly call them. These strange, twisted formations are usually composed of the carbonate minerals calcite or aragonite, and they grow in any direction, seemingly defying gravity. But how? There are many theories, but science has revealed that surface diffusion, surface tension, capillary force, crystal lattice orientation, and directional evaporation can all play a role in outcompeting gravitational mineral growth. Some helictites grow up from the floor to a height of over a metre and are known as ‘snake dancers’. An extremely rare variant of calcite helictites forms underwater under special hydrochemical conditions.