Alluaudites, wyllieites, arrojadites: crystal chemistry and nomenclature | Mineralogical Magazine | Cambridge Core (original) (raw)
Synopsis
A nomenclature is proposed for the alluaudite and wyllieite complex series which is based on sequentially distributing the cations in the cell according to increasing polyhedral size, matching that size with increasing ionic radii of the cations. For oxidized members, the largest site may be partly occupied to empty after all the cations have been distributed. This is supported by structural study.
For alluaudites, the cell formula is X(2)4X(I)4 M(I)4M(2)8(PO4)12 and is written according to decreasing size of the discrete sites. The X(I) and X(2) sites are appended as suffixes in the trivial nomenclature, that is specific name—X(I)X(2).
For wyllieites, the cell formula is X(2)4X (1a)2X(1b)2M(I)4M(2a)4A14(PO4)12. The X(1a), X(1b), and X(2) sites are appended as suffixes in the trivial nomenclature, that is specific name--X(la) X(Ib)X(2).
The nomenclature proposed is:
Seventeen analyses are discussed (of which five are new) for alluaudite and four analyses (of which three are new) for wyllieites. Their distribution is given parenthetically above. One analysis revealed predominant Mg2+ in M(2). It is named maghagen-dortite.
Six new analyses are presented for the arrojadite family of minerals including re-examination of dickinsonite from Branchville, Connecticut. Al3+ is always present. We propose X1 Al (OH,F)(PO4)12, Z = 4, where X = large cations (K+, Ba2+, Pb2+, etc.), Y = Na1+, Ca2+, and M = Fe2+ Mn2+, Mg2+. A range of cations X, Y, M, and Al between 76.8 and 85.9 in the cell (84 for proposed formula) suggests the likelihood of some vacancies in the structure.
Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1979
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References
Berman, (H.), and Gonyer, (F. A.), 1930. Amer. Min. 15, 575.Google Scholar
Eriksson, (T.), 1946. Ark. Kemi mineral. Geol. A23 (no. 8), 14 pp.Google Scholar
Eventoffo, (W.) , Martin, (R.), and Peacor, (D. R.), 1972, Amer. min., 57 45.Google Scholar
Guimarães, (D.), 1942. BOZ. Fac. Fil. Ciên Let. Univ. San Paolo 30 (Mineralogia 5, 1)Google Scholar
Huvelin, (P.) Orliac, (H.), and Permingeat, (Fr.), 1972. Notes Serv. gêol. Maroc 32, 35.Google Scholar
Von Knopring, (O.), 1969. Bull, Serv. Geol. Rwanda, 5 42.Google Scholar
Moore, (P.B.) and Araki, (T.), 1977. Amer. Min. 62, 229,Google Scholar
Moore, (P.B.) and Molin-Cass, (J.-A.), 1974. Amer. Min.59, 280.Google Scholar
Palache, (C.), Berman, (H.), and Frondel, (C.), 1951, The System of Mineralogy of Dana, Vol. II.Seventh Ed. John Wiley and Sons (New York), p. 664.Google Scholar
Pehrman, (G.), 1939, Acta Acad. Aboensis, Math. Phys, 12 (No. 6), 24 pp.Google Scholar
Quensel, (P.), 1937. Geol. Fören. Stockholm Förhandl. 58, 621.Google Scholar
Thoreau, (J.s.) and Bastien, (G.), 1954. Acad. roy. Soc. colon. BUll. Séances 25(5), 1595Google Scholar