helictites

Helictites are a form of speleothem, mineral formations that occur in caves. Unlike stalactites or stalagmites, helictites grow in irregular, twisting, or branching directions, often extending outward from ceilings or walls as if defying gravity. They are commonly composed of calcite or aragonite, though other minerals such as gypsum can form related structures.

Helictite formation is influenced by microclimate and water movement within a cave. Mineral-rich water seeping through cracks may deposit tiny crystals along capillary paths, and small air currents or humidity gradients can bias growth away from a straight downward direction. As crystals accumulate at irregular surfaces, growth can proceed along multiple axes, producing tentacle-like, corkscrew, or forked shapes. The result is a delicate, often fragile structure that may appear to grow in mid-air from a rock face or ceiling.

In appearance, helictites vary from slender, hair-like spires to thicker, branching forms. They are typically pale white to tan, sometimes tinted by trace minerals. Because their growth depends on precise and variable cave conditions, they are more irregular and less common than stalactites or stalagmites. They can take thousands of years to reach noticeable sizes.

Helictites occur in many cave systems around the world and are of interest to speleologists studying past cave climates. They are delicate and can be damaged by touch, vibration, or changes in humidity, so preservation in show caves is common.