Stalactite

A stalactite (UK: /ˈstæləkˌtaɪt/, US: /stəˈlæktaɪt/; from Ancient Greek σταλακτός (stalaktós) 'dripping', from σταλάσσειν (stalássein) 'to drip')[1] is a mineral formation that hangs from the ceiling of caves, hot springs, or man-made structures such as bridges and mines.

Stalactites may be composed of lava, minerals, mud, peat, pitch, sand, sinter, and amberat (crystallized urine of pack rats).

[5] The chemical formula for this reaction is:[6] This solution travels through the rock until it reaches an edge and if this is on the roof of a cave it will drip down.

Too fast a drip rate and the solution, still carrying most of the CaCO3, falls to the cave floor where degassing occurs and CaCO3 is deposited as a stalagmite.

Eventually, these rings form a very narrow (≈4 to 5 mm diameter), hollow tube commonly known as a "soda straw" stalactite.

Stalactite formation generally begins over a large area, with multiple paths for the mineral rich water to flow.

The same water drops that fall from the tip of a stalactite deposit more calcite on the floor below, eventually resulting in a rounded or cone-shaped stalagmite.

Trapped gases expansion forces lava to extrude out through small openings that result in hollow, tubular stalactites analogous to the soda straws formed as depositional speleothems in solution caves.

These are common in Hawaiian lava tubes and are often associated with a drip stalagmite that forms below as material is carried through the tubular stalactite and piles up on the floor beneath.

Sometimes the tubular form collapses near the distal end, most likely when the pressure of escaping gases decreased and still-molten portions of the stalactites deflated and cooled.

Often these tubular stalactites acquire a twisted, vermiform appearance as bits of lava crystallize and force the flow in different directions.

These secondary deposits, such as stalactites, stalagmites, flowstone and others, which are derived from the lime, mortar or other calcareous material in concrete, outside of the "cave" environment, can not be classified as "speleothems" due to the definition of the term.

A straw shaped stalactite which has formed under a concrete structure can grow as much as 2 mm per day in length, when the drip rate is approximately 11 minutes between drops.

[14] Changes in leachate solution pH can facilitate additional chemical reactions, which may also influence calthemite stalactite growth rates.

[citation needed] Another such claim is made for a 20 m (66 ft) limestone stalactite that hangs in the Chamber of Rarities in the Gruta Rei do Mato (Sete Lagoas, Minas Gerais, Brazil).