When stalactites and stalagmites touch, they can form what kind of structure?

When a stalactite touches a stalagmite it forms a column. Usually, stalactites and stalagmites in caves are formed by calcite, less frequently by aragonite, and rarely by gypsum. Fifty-four other cave minerals are known to form rare stalactites.

Sometimes calcite stalactites or stalagmites are overgrown by aragonite crystals. This is due to precipitation of calcite that raises the ratio of magnesium to calcium in the solution enough that aragonite becomes stable.

Rarely, elongated single crystals or twins of calcite are vertically oriented and look like stalactites, but in fact are not stalactites because they are not formed by dripping or flowing water and don’t have hollow channels inside. These elongated crystals are formed from water films on their surface.

The internal structure of stalactites and stalagmites across their growth axis usually consists of concentric rings around the hollow channel. These rings contain different amounts of clay and other inclusions, and reflect drier and wetter periods. Clay rings reflect hiatuses of the growth of the sample. Stalagmites may be formed for periods ranging from a few hundreds years up to one million years. Stalactites and stalagmites in caves have such great variety of shapes, forms, and color that each of them is unique in appearance. At the same time, their growth rates are so slow that once broken, they cannot recover during a human life span of time. Thus, stalactites and stalagmites are considered natural heritage objects and are protected by law in most countries, and their collection, mining, and selling is prohibited.

Credit : Encyclopedia.com 

Picture Credit : Google

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