Helictites are contorted depositional speleothems which grow in any direction, seemingly defying gravity. They occur in many forms from tiny filaments (as in the middle photo) to thick, antler-like forms (bottom photo). Most helictites are formed from calcite. Helictites are formed by calcite-laden waters seeping through tiny pores in the rock. Hydrostatic pressure forces a small amount of the solution out, carbon dioxide is lost, and calcite is deposited. Growth continues through a tiny, central capillary chanel, which the solution flows through via hydrostatic and capillary pressure to emerge and deposit calcite at the tip. Helictites are a very diverse group of speleothems, likely because different factors influence them. There is a very rare category that forms underwater, best known from Lechuguilla Cave, New Mexico. One show cave in California, Black Chasm Cavern, was designated a National Natural Landmark because of this. Visit our special tribute page to this cave's diverse helictites. The twisted shapes are due to many factors, including: (1) impurities in the deposited calcite (2) wedge-shaped crystals causing uneven deposition (3) plugging of the central channel may occur in dry periods, and when flow resumes, the pressure may force a new channel out the side of the original one (4) air currents may favor growth in a particular direction. Sometimes helictites are found facing the same direction down a passage (see upper left photo in thumbnail table below).

 

beaded helictites	directional helictites	subaqueous helictites

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	Created: June 19, 1995 Last Updated: May 4, 2005 Author: Dave Bunnell