Speleothem

As Speläothem or cave mineral of the speleologist means any secondary mineral deposits in caves; but it may also occur in other damp cavities such as mines and tunnels. The most common speleothems are speleothems ( sintering ) or stalactites. Mostly they consist of the minerals calcite and aragonite, or calcium carbonate compound (lime ), often are also various forms of gypsum. In suitable rocks such as sandstone or quartzite speleothems from Opal occur beyond.

There are thousands of different forms of speleothems. However, most of these are extremely rare and occur in only a few caves in the world.

Origin of the term

For Speläothem also a German word that cave mineral exists. This term is increasingly being replaced at the time by Speläothem, a composition from the Greek words σπηλαίων ( Spelaion, cave ) - the caving and speleologist ( cavers ) is in the terms - and θέμα ( theme, deposition ).

The term was coined in 1952 by the American cavers GW Moore coined and is used by geologists and cavers used primarily to achieve a uniform international parlance.

Distinction between the terms

The terms Speläothem and the well-known stalactite classify minerals according to different criteria. This requires a more detailed explanation of the differences.

Resulting from rearrangements of material in the rock formations usually consist of minerals. A subset of them arises in caves and is therefore an obvious manner called cave mineral. Stalactites caused by dripping water, exact previously removed by the precipitation material from the water. The name suggests that the water flows, resulting in the formation of other mineral forms as in standing water.

The two terms stalactite and Speläothem therefore have a significant intersection, namely the incurred in caves stalactites. Since speleothems can also occur in mines and buildings and there are minerals in caves, which did not occur in flowing water, there are both stalactites and stalagmites that are not speleothems, and vice versa speleothems that are not stalactites. In this context, therefore, is often incomprehensible that speleothems in mines are indeed naturally occurring minerals, but it is not speleothems in the strict sense, because they have arisen in other cavities.

Common speleothems

  • Speleothems canopies
  • Inter ceiling bar
  • Knöpfchen Inter ( Perlsinter, cauliflower Inter)
  • Macaroni ( soda straws, tubes Inter)
  • Sintering flag ( sintered curtain)
  • Sintering (sinter crust )
  • Sintered pool
  • Sintering ceiling
  • Sintering case
  • Stalagmite
  • Stalagnat ( stalagmite )
  • Stalactite
  • Wall interaction Wreath
  • Inter wall bar
  • Boxwork
  • Excentrique
  • Gypsum flower
  • Cave pearl
  • Kalkhäutchen
  • Moonmilk

Special forms

Cave pearls

First, be undermined by drops on a soft soil shallow depressions, the sinter by calcium deposits. In these basins occur cave pearls when lime deposits around a condensation nucleus of sediment particles or rock fragments. Through constant movement of water, such as by dripping water, this grain is continuously rotated. Here layers of travertine (often also aragonite ) deposited slowly. If the cave pearl too heavy, so that it no longer moves, it can also be grown. From such collections of cave pearls consists of pea stone.

Kalkhäutchen

Kalkhäutchen consist of small calcite crystals that float on the water of a sintered basin. If they are too heavy, they sink and form very characteristic puff - like deposits.

Opal speleothems

In silicate rocks such as sandstone and quartzite under special conditions speleothems can occur which do not consist of carbonate, but from silicates such as opal or quartz. Examples of such developments are found particularly widespread in the caves of the South American tepuis, such as in Muchimuk cave system or in the Cueva Ojos de Cristal of Roraima Tepui. Described were more than a dozen forms of fungus, kidney or ball shape, branched coral with similar shape and irregular.

The occurrence of these formations is explained by the evaporation of cave water with dissolved silicon dioxide enrichment and the precipitation of finely atomized water on walls and ceilings beyond the control of running water. The precipitation of opal was also observed on cobwebs, which coincided with the distribution of material in and formed stalactites -like shapes.

A special role in the formation of opal speleothems play bacteria that can be detected in the material of the speleothems.

Kents Cavern Torquay England Rimstone Pisolite National Speleological Society
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