- Moonmilk
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Moonmilk in the cave Bergmilchkammer
Moonmilk (sometimes called mondmilch, German for moonmilk or sometimes wrongly montmilch) is a white, creamy substance found inside caves. It is similar to other deposits, but its unique quality is that it does not harden or turn to stone. It is a precipitate from limestone comprising aggregates of fine crystals of varying composition usually made of carbonate materials, e.g., calcite, hydromagnesite, and monohydrocalcite.
Hypotheses about the origin of moonmilk are mixed. Some scientists think it is a bacterial action rather than a chemical one. In this theory, it is thought to be created by the bacterium Macromonas bipunctata. Certain bacterial actions are known to be capable of breaking down stone to form this semiliquid "milk". However, no microbiological studies have been carried out so far.
It was originally thought (by Conrad Gesner, 1555) to be created by "moon rays."
The discovery of a 150 meter long moonmilk river was first announced on March 2004 by a team of speleologists in a cavern in Guipúzcoa, Spain. This river is formed by a thick milk-like fluid composed by calcite, quarz and brushite.
It is possible that moonmilk is formed by extruding water percolations that dissolve and soften the carbonate walls of karstic caves and carry dissolved nutrients that can be used by epilithic microbes, such as actinomycetes. As the microbial colonies grow, they trap and accumulate chemically-precipitated crystals in the organic matter-rich matrix formed that way. Perhaps these heterotrophic microbes, which produce CO2 as a waste product of respiration and maybe organic acids, help to dissolve the carbonate as well. Of course, more research is needed to prove any current hypothesis.
References
- George W. Moore and Nicholas Sullivan. Speleology: Caves and the Cave Environment, rev. 3rd ed. Dayton, Ohio: Cave Books, 1997. ISBN 0-939748-46-0 (hardcover), ISBN 0-939748-45-2 (paperback).
- Cave Formations
External links
Categories:- Speleothems
- Bacteria stubs
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