Fluorcarmoite-(BaNa) explained
| Fluorcarmoite-(BaNa) |
| Category: | Phosphate |
| Formula: | Ba[]Na2Na2[]CaMg13Al(PO4)11(PO3OH)F2 |
| Imasymbol: | Fcm-BaNa[1] |
| System: | Monoclinic |
| Class: | Domatic (m)
(same H-M symbol) |
| Symmetry: | Cc |
| Unit Cell: | a = 16.40, b = 9.95
c = 24.45 [Å]; β = 105.73° (approximated) |
Fluorcarmoite-(BaNa) is a rare phosphate mineral, belonging to arrojadite group, with the formula Ba[]Na2Na2[]CaMg13Al(PO4)11(PO3OH)F2.[2] It is a barium-rich member of the group, as is arrojadite-(BaNa), arrojadite-(BaFe), fluorarrojadite-(BaFe)[3] and an unapproved species ferri-arrojadite-(BaNa).[4] The "-(BaNa)" suffix informs about the dominance of the particular elements (here barium and sodium) at the corresponding structural sites.[5]
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.[6]
Notes and References
- Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
- 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
- Web site: Fluorcarmoite-(BaNa): Fluorcarmoite-(BaNa) mineral information and data . Mindat.org . 2016-03-12.
- Web site: Ferri-arrojadite-(BaNa): Ferri-arrojadite-(BaNa) mineral information and data . Mindat.org . 2016-03-12.
- 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
- 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.
