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Unnamed (Amorphous Calcium Carbonate)

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CaCO3 · H2O
water content variable, possibly depending on biogenic type
Crystal System:
An amorphous precursor of crystalline calcium carbonates, in particular of vaterite. Abbreviated as ACC. The least stable CaCO3 polymorph; stabilized by some microorganisms (Hodson et al., 2015). A biomaterial; rapidly dehydrates to vaterite, which is later turned to calcite via dissolution-reprecipitation mechanism (Rodriguez-Blanco et al., 2011). The ACC-to-vaterite transformation is inhibited by PO43- ions (Bots et al., 2012).

May spontaneously form in water by high saturation of essential ions; there it exists as nanospheres (50-400 nm) (Brečević et al., 1989).

Also a precursor of carbonate-rich hydroxylapatite in human bone, stabilized by inorganic polyphosphate; has osteogenic potential (Tolba et al., 2016).

May show short-range structural forms (related to calcite, aragonite, monohydrocalcite, but not necessarily to vaterite) and thus possibly various types exist (Cartwright et al., 2012).

Compare monohydrocalcite (the ACC may in fact turn into it when in aqueous solution, as shown in a biomimetic mineralization study by Wang et al., 2015).

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Chemical Properties of Unnamed (Amorphous Calcium Carbonate)Hide

CaCO3 · H2O

water content variable, possibly depending on biogenic type

Crystallography of Unnamed (Amorphous Calcium Carbonate)Hide

Crystal System:

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Unnamed (Amorphous Calcium Carbonate)Hide

Reference List:
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Brečević, L., Nielsen, A.E. (1989): Solubility of amorphous calcium carbonate. Journal of Crystal Growth: 98(3), 504-510
Rodriguez-Blanco, J.D., Shaw, S. and Benning, L.G. (2011): The kinetics and mechanisms of Amorphous Calcium Carbonate (ACC) crystallization to calcite, via vaterite. Nanoscale: 3: 265-271
Bots, P., Rodriguez-Blanco, J.D., Roncal-Herrero, T., Benning, L.G., Shaw, S. (2012): Mechanistic insights into the crystallization of amorphous calcium carbonate to vaterite. Crystal Growth and Design: 12: 3806-3814
Cartwright, J.H.E., Checa, A.G., Gale, J.D., Gebauer, D., Sainz-Díaz, I. (2012): Calcium carbonate polyamorphism and its role in biomineralisation: How many ACCs are there? Angew Chem Int Ed Engl.: 51(48): 11960-70
Hodson, M.E., Benning, L.G., Demarchi, B., Penkman, K.E.H., Rodriguez-Blanco, J.D., Schofield, P.F., Versteegh, E.A.A. (2015): Biomineralisation by earthworms – an investigation into the stability and distribution of amorphous calcium carbonate. Geochemical Transactions: 16: 4
Tolba, E., Müller, W.E.G., Abd El-Hady, B.M., Neufurth, M., Wurm, F., Wang, S., Schröder, H.C., Wang, X. (2016): High biocompatibility and improved osteogenic potential of amorphous calcium carbonate/vaterite. Journal of Materials Chemistry B: 4: 376-386
Sugiura, Y., Onuma, K., Yamazaki, A. (2016): Growth dynamics of vaterite in relation to the physico-chemical properties of its precursor, amorphous calcium carbonate, in the Ca-CO3-PO4 system. American Mineralogist: 101: 289-296
Wang, Y.Y., Yao, Q.-Z., Zhou, G.-T., Fu, S.-Q. (2015): Transformation of amorphous calcium carbonate into monohydrocalcite in aqueous solution: a biomimetic mineralization study. European Journal of Mineralogy: 27(6): 717-729

Internet Links for Unnamed (Amorphous Calcium Carbonate)Hide

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