Unnamed (Amorphous Calcium Carbonate)
A material that is NOT an approved mineral species
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About Unnamed (Amorphous Calcium Carbonate)
Formula:
CaCO3 · H2O
water content variable, possibly depending on biogenic type
Crystal System:
Amorphous
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).
May be precipitated by some molds, in relatively huge quantities.
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).
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).
May be precipitated by some molds, in relatively huge quantities.
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).
Unique Identifiers
Mindat ID:
47449
Long-form identifier:
mindat:1:1:47449:6
GUID
(UUID V4):
(UUID V4):
4654649d-44e4-4f66-a5a7-0598f7f08a2a
Chemical Properties of Unnamed (Amorphous Calcium Carbonate)
Formula:
CaCO3 · H2O
water content variable, possibly depending on biogenic type
water content variable, possibly depending on biogenic type
Elements listed:
Crystallography of Unnamed (Amorphous Calcium Carbonate)
Crystal System:
Amorphous
Other Information
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)
Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
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-DĂaz, 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.
Garvie, L.A.J., Nèmeth, L., Trif, L. (2021): An Exceptionally Stable and Widespread Hydrated Amorphous Calcium Carbonate Precipitated By the Dog Vomit Slime Mold Fuligo Septica (Myxogastria). Scientific Reports: 12: 3642.
Internet Links for Unnamed (Amorphous Calcium Carbonate)
mindat.org URL:
https://www.mindat.org/min-47449.html
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Mineral Dealers:
Florida, USA