Fluorcarmoite-(BaNa)

Fluorcarmoite-(BaNa) is a rare phosphate mineral, belonging to arrojadite group, with the formula Ba[]Na2Na2[]CaMg13Al(PO4)11(PO3OH)F2.[1] It is a barium-rich member of the group, as is arrojadite-(BaNa), arrojadite-(BaFe), fluorarrojadite-(BaFe)[2] and an unapproved species ferri-arrojadite-(BaNa).[3] The "-(BaNa)" suffix informs about the dominance of the particular elements (here barium and sodium) at the corresponding structural sites.[4]

Fluorcarmoite-(BaNa)
General
CategoryPhosphate
Formula
(repeating unit)
Ba[]Na2Na2[]CaMg13Al(PO4)11(PO3OH)F2
Crystal systemMonoclinic
Crystal classDomatic (m)
(same H-M symbol)
Space groupCc
Unit cella = 16.40, b = 9.95
c = 24.45 [Å]; β = 105.73° (approximated)
Identification
References[1][2]

Arrojadite group

The arrojadite group is defined in form of the complex, general formula A2B2CaNa2+xM13Al(PO4)11(PO3OH1−x)W2, where:

  • A = large divalent cations (barium, lead, strontium) and vacancy ([]), eventually monovalent cations (potassium, sodium)
  • B = small divalent cations (iron, manganese, magnesium) and vacancy ([]), eventually sodium
  • M = Fe2+ (this gives the root name arrojadite) or Mn2+ (root name dickinsonite), or eventually Mg
  • W = hydroxyl group or fluorine

The two suffixes in the name correspond to A1 and B1 sites. Third suffix may be present in special cases.[5]

References

  1. Cámara, F., Bittarello, E., Ciriotti, M.E., Nestola, F., Radica, F., and Bracco, R., 2015. Fluorcarmoite-(BaNa), IMA 2015-062. CNMNCNewsletter No. 27, October 2015, 1229; Mineralogical Magazine 79, 1229–1236
  2. "Fluorcarmoite-(BaNa): Fluorcarmoite-(BaNa) mineral information and data". Mindat.org. Retrieved 2016-03-12.
  3. "Ferri-arrojadite-(BaNa): Ferri-arrojadite-(BaNa) mineral information and data". Mindat.org. Retrieved 2016-03-12.
  4. Hatert, F., Mills, S.J., Pasero, M., and Williams, P.A., 2013. CNMNC guidelines for the use of suffixes and prefixes in mineral nomenclature, and for the preservation of historical names. European Journal of Mineralogy 25, 113-115
  5. Chopin, C., Oberti, R., and Cámara, F. 2006. The arrojadite enigma: II. Compositional space, new members and nomenclature of the group. American Mineralogist 91, 1260-1270.


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