Editing Helictite (section)

== Formation ==
{{Original research|section|date=December 2015}}
[[File:Tropfsteine.svg|right|thumb|Diagram of dripstone cave structures (helictites are labeled H)]]
The growth of helictites is still quite enigmatic. To this day, there has been no satisfactory explanation for how they are formed. Currently, formation by capillary forces is the most likely hypothesis, but another hypothesis based on wind formation is also viable. 

=== Capillary forces ===
The most likely hypothesis explains helictites as a result of capillary forces. If the helictite has a very thin central tube where the water flows as it does in straws, capillary forces would be able to transport water against gravity. This idea was inspired by some hollow helictites. However, the majority of helictites are not hollow. Despite this, droplets can be drawn to the tips of existing structures and deposit their calcite load almost anywhere thereon. This can lead to the wandering and curling structures seen in many helictites.

===Wind===
Another hypothesis names the wind in the cave as the main reason for the strange appearance. Drops hanging on a [[stalactite]] are blown to one side, so the dripstone grows in that direction. If the wind changes, the direction of growth changes too. However, this hypothesis is very problematic, because wind directions change very often. The wind in caves depends on air pressure changes outside, which in turn depend on the weather. The wind direction changes as often as the weather conditions outside change. But the dripstones grow very slowly – several centimeters in 100 years – meaning that the wind direction would have to stay steady for long periods of time, changing for every fragment of a millimeter of growth. A second problem with this idea is that many caves with helictites have no natural entrance where wind could enter.

===Piezoelectric forces===
Another hypothesis that has been proposed is that slowly changing geological pressure causing stresses on the crystals at the base alters the piezo electrostatic potential and causes particle deposition to be oriented in some relationship to the prevailing pressure orientation.

===Bacterial===
A recent hypothesis, which is supported by observation, is that a prokaryotic bacterial film provides a nucleation site for mineralization process.<ref>Tisato, N. et al., [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4625141/pdf/srep15525.pdf "Microbial mediation of complex subterranean mineral structures"], Sci. Rep. 5, 15525; doi: 10.1038/srep15525 (2015) </ref>