Stalactite
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A stalactite is a mineral formation that hangs from the ceiling of caves, hot springs, or man-made structures such as bridges and mines. Any material that is soluble and that can be deposited as a col
Image showing the six most common speleothems with labels. Enlarge to view labels.
Pillars in the Caves of Nerja, Spain
Shark tooth stalactites
Ice stalactites on the gutter of a house
Lava tube
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A lava tube, more rarely called a pyroduct or lava tunnel, is a natural roofed conduit along which molten lava flows from a volcanic vent. If lava in the tube drains out, it will leave an empty cave.
Stalactite
…formations can meet and fuse to create a speleothem of calcium carbonate known as a pillar, column, or stalagnate. Another type of stalactite is formed in lava tubes while molten and fluid lava is still active inside. The mechanism of formation is the deposition of molten dripping material on the ceilings of caves…
Valentine Cave, a lava tube in Lava Beds National Monument, California shows the classic tube shape; the grooves on the wall mark former flow levels.
Thurston Lava Tube in Hawaii Volcanoes National Park, Hawaii. The step mark, more visible on the right wall, indicates the depth at which the lava flowed for a period of time.
Rare characteristics of lava tubes are lava pillars. This is the Manjanggul lava pillar located in the Manjanggul lava tubes, on the island of Jeju-do, Korea.
Lavacicles on the ceiling of Mushpot Cave in Lava Beds National Monument