Stalactites are a type of speleothem (cave formation). Many of them get their start as soda straws. These speleothems are long hollow tubes that look like a drinking straw. Water flows through them and leaves behind a thin ring of mineral as it drips out, growing the “straw”.
If the tube gets blocked or water starts to flow on the outside, it can turn into a large formation. This stalactite is called the Crystal King at Ohio Caverns. It’s over 200,000 years old, nearly 5 feet long and is estimated to weigh about 400 pounds.
Some grow at odd angles and form helictites. It is unclear exactly how they grow this way. One theory is that wind in the cave blows the dripping water one way or another. The other major theory is that simple capillary action of the water forms them.
When stalactites grow together in a group, they often resemble a chandelier.
Photo Courtesy of GSloan
Discovering new and different types of cave formations is part of the adventure of caving. Kartchner Caverns in Arizona contain “turnip shields” that resemble the vegetable. They are unknown in other cave systems.
While most of these cave formations are formed by a water-mineral solution slowly dripping over time, there are some exceptions.
Lava tubes can have “lava sickles” that were formed by dripping lava that cooled when the cave itself was formed.
Ice caves often contain ice sickles, which of course are formed by water dripping and freezing.