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Description
Mondmilch, or moon milk, is a special type of speleothems (secondary mineral formations formed in a cave environment from a primary mineral as a result of physical and chemical reactions). This mineral formation is a soft clay-like substance with a high water content, which becomes fluid when touched. In caves, mondmilch is found in the form of covers, leaks, lumps on the walls and on the floor, extensive deposits and small solitary formations. The composition of moon milk dependes on the rocks in which the underground cavity is located. It can be carbonate, gypsum, aluminosilicate and phosphate [Chirienco, 2004].
The questions of the moon milk origin and the variability of its crystalline structure are con-troversial. It remains uncertain as the thixotropic characteristics (fluidity) of the sediment and water content are changing in accordance with the features of the crystals formed the formation. It is possible that there are some regularity between the composition, structure of the crystals and the physical properties of this type of sediment. There is also a hypothesis about the biogenic origin of the moon milk. It is known that microorganisms of different physiological groups were found in the secondary formation content [Hill, Forti, 1997], and it can be assumed that microorganism cells can act as crystallization centers during the formation of moon milk, but the hypothesis that the microbiota is secondary in the content of moon milk and the sedimentation is its habitat.
This paper presents the data on chemical composition and morphology of crystals of the samples of moon milk (mondmilch) from Botovskaya cave, which is the largest in Russia. It was determined that moon milk is characterized by increased concentrations of Ca and Sr and lower contents of Ti, Mn and Fe relatively to the host rocks. The morphology of mondmilch crystals indicates that the genesis of this secondary mineral formation is based on both abiogenic and biogenic mechanisms.
It should also be noted that this type of sediment has been studied using the XRF SR method for the first time. The examination of sampled specimens provides new information on chemical composition and structure of moon milk in caves of carbonate karst.
This work is partially supported by RFBR grant №13-05-90780.
References
Chirienco M. The crystalline phase of the carbonate moonmilk: a terminology approach // Acta carstologica, 33/1, 2004. p. 257-264.
Hill C. A., Forti P., Cave minerals of the world // NSS. Huntsville, 1997. p. 463.
Summary
This paper provides the information on chemical composition and morphology of crystals of moon milk samples (mondmilch) from Botovskaya cave, the largest in Russia. This type of sediment has been studied with the application of XRF SR method for the first time. The research of sampled specimens provides new information on chemical composition and structure of moon milk in carbonate karst caves.
