Monohydrocalcite

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Monohydrocalcite is a mineral that is a hydrous form of calcium carbonate, CaCO₃.H₂O. It is a trigonal mineral which is white when pure. Monnohydrocalcite is not a common rock-forming mineral, but is frequently associated with other calcium and magnesium carbonate minerals, such as calcite, aragonite, lansfordite and nesquehonite.

Monohydrocalcite has been observed in air conditioning systems, and as a deposit in caves, both probably formed from spray of carbonate rich fluids. It is well-known in the Robe district of South Australia as a component of beach sands of Lake Fellmongery and Lake Butler, where it is believed to be an evaporite. It has been reported as a significant component of the decomposition of ikaite in the towers of the Ikka Fjord. It is also noted for its bizarre occurrences, which include inside the otoliths of the tiger shark, the bladder of a guinea pig, the skull of an extinct cave bear, and the putrefying flesh of the giant saguaro cactus. These occurrences suggest a biochemical origin is possible.

[edit] Further Reading

Catherine, H., Skinner, K., Osbaldiston, G. W., Wilner, A. N. Monohydrocalcite in a guinea pig bladder stone, a novel occurrence. American Mineralogist, 62: 273 - 277, 1977.
Dahl, K., Buchardt B. Monohydrocalcite in the arctic Ikka Fjord, SW Greenland:First reported marine occurrence. Journal of Sedimentary Research, 2006, vol. 76. DOI: 10.2110/jsr.2006.035
Garvie, L.A.J. Decay-induced biomineralization of the saguaro cactus (Carnegiea gigantea) American Mineralogist, 88: 1879-1888, 2003
Hull, H., Turnbull, A. G. A thermochemical study of monohydrocalcite. Geochimica et Cosmochimica Acta, 37: 685-694, 1973