From Surf Wiki (app.surf) — the open knowledge base

Monohydrocalcite

Hydrate form of calcium carbonate

Field	Value
name	Monohydrocalcite
image	Monohydrocalcite crystals.jpg
caption	Colorless monohydrocalcite crystals
category	Carbonate minerals
formula	CaCO3·H2O
IMAsymbol	Mhcal
strunz	5.CB.20
system	Trigonal
class	Trapezohedral (32)
(same H-M symbol)
symmetry	P3121
struct image	monohydrocalcite.jpg	struct caption=The crystal structure of monohydrocalcite. Ca is shown as a blue atom, O atoms red, and the carbonate anion and water molecules are shown as bonded entities.	prop1text =
references

(same H-M symbol) | length fast/slow =

Monohydrocalcite is a mineral that is a hydrous form of calcium carbonate, CaCO3·H2O. It was formerly also known by the name hydrocalcite, which is now discredited by the IMA. It is a trigonal mineral which is white when pure. Monohydrocalcite 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 in moonmilk deposits in caves, both probably formed from spray of carbonate rich fluids. It is well known in Robe on the Limestone Coast of South Australia as a component of beach sands of Lake Fellmongery and Lake Butler, where it is believed to be formed from algal spume. Other lacustrine deposits include Lake Issyk-Kul, Kyrgyzstan, Lake Kivu, Democratic Republic of the Congo, and Solar Lake, Sinai.

It has been reported as a significant component of the decomposition of ikaite in the towers of the Ikka Fjord, West Greenland. It is also noted for its bizarre occurrences, which include inside the otoliths of the tiger shark, the bladder of a guinea pig, the calcareous corpuscles of a cestode parasite, and the final stages of decomposition of the putrefying flesh of the giant saguaro cactus. These occurrences suggest a biochemical origin is possible.

Formation of monohydrocalcite

Monohydrocalcite forms via a Mg-rich amorphous calcium carbonate (ACC) precursor. This Mg-rich ACC forms rapidly (seconds) and then transforms to monohydrocalcite via dissolution and reprecipitation, with monohydrocalcite forming via a nucleation-controlled reaction like spherulitic growth.

Recent studies have highlighted the importance of Mg in the formation process of monohydrocalcite. The presence of Mg in solution is known to inhibit the formation of vaterite and calcite. However, the hydrated nature of monohydrocalcite means that full dehydration of Mg is not required before incorporation of this ion into this mineral and therefore it will more likely form than the anhydrous calcium carbonate phases.

Footnotes

References

Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Monohydrocalcite Mineralienatlas]
(2008). "The structure of monohydrocalcite and the phase composition of the beachrock deposits of Lake Butler and Lake Fellmongery, South Australia". [[American Mineralogist]].
(2006). "Monohydrocalcite in the arctic Ikka Fjord, SW Greenland:First reported marine occurrence". [[Journal of Sedimentary Research]].
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.
(2008). "Monohydrocalcite in calcareous corpuscles of ''Mesocestoides corti''". [[Experimental Parasitology]].
Garvie, L.A.J. Decay-induced biomineralization of the saguaro cactus (''Carnegiea gigantea'') [[American Mineralogist]], 88: 1879–1888, 2003.
(2014). "The role of Mg in the crystallisation of monohydrocalcite". Geochimica et Cosmochimica Acta.

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

calcium-minerals carbonate-minerals

Want to explore this topic further?

Ask Mako anything about Monohydrocalcite — get instant answers, deeper analysis, and related topics.

Research with Mako

Free with your Surf account

Content sourced from Wikipedia, available under CC BY-SA 4.0.

This content may have been generated or modified by AI. CloudSurf Software LLC is not responsible for the accuracy, completeness, or reliability of AI-generated content. Always verify important information from primary sources.

Report