Wilancookite, (Ba,K,Na)8(Ba,Li,[])6Be24P24O96·32H2O, a new 2 beryllophosphate with a zeolite framework.
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Data
2017
Autores
Hatert, Frédéric
Philippo, Simon
Ottolini, Luisa
Bol, Fabrice Dal
Cipriano, Ricardo Augusto Scholz
Chaves, Mario Luiz de Sá Carneiro
Yang, Hexiong
Downs, Robert T.
Menezes Filho, Luiz Alberto Dias
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Resumo
Wilancookite, ideally (Ba,K,Na)8(Ba,Li,[])6Be24P24O96·32H2O, is a new mineral species from the Lavra Ponte do Piauí
19 complex granitic pegmatite, Minas Gerais, Brazil. It occurs as tiny dodecahedral {1 1 0} crystals, deposited on moraesite fibres.
20 Associated primary minerals are albite, montebrasite, Li-bearing micas, cassiterite, elbaite and quartz, while the secondary phosphate
21 association contains fluorapatite, childrenite, eosphorite, zanazziite, greifenstenite, guimarãesite, ushkovite, saléeite and moraesite.
22 The mineral is transparent and colourless, with a vitreous lustre; it is non-fluorescent, brittle, and its streak is white. The estimated
23 Mohs hardness is 4–5, and the calculated density is 3.05 g/cm3.Wilancookite is isotropic, colourless, non-pleochroic, with n = 1.560(2)
24 (measured under l = 590nm). Electron- and ion-microprobe analyses give (in wt%): P2O5 36.19, SiO2 0.04, Al2O3 0.41, BaO
25 34.65, Na2O 0.09, K2O 0.32, BeO 12.86, Li2O 0.50, and H2Ocalc 12.31, total 97.37wt%. The resulting empirical formula, calculated
26 on the basis of 96 anhydrous oxygen atoms, is (Ba7.54K0.32Na0.14)S8.00(Ba3.04Li1.57[]1.39)S6.00Be24.08(P23.88Al0.38Si0.03)S24.29
27 O96·32H2O. The single-crystal unit-cell parameters are a = 13.5398(2)A
and V = 2482.21(7), space group I23. The eight strongest
28 lines in the powder X-ray diffraction pattern [d(in A
)(I)(hkl)] are: 6.90(60)(2 0 0), 5.54(80)(2 1 1), 3.630(60)(3 2 1, 3 1 2), 3.212(70)
29 (3 3 0, 4 1 1), 3.043(100)(4 2 0, 4 0 2), 2.885(70)(3 3 2), 2.774(80)(4 2 2), and 2.398(60)(4 4 0). The crystal structure of wilancookite
30 has been refined, based on single-crystal X-ray diffraction data, to R1 = 4.58%; the beryllophosphate framework is similar to that
31 occurring in pahasapaite, and is based on zeolite-RHO cages. The mineral species and name were approved by the Commission on
32 New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2015-034).
Descrição
Palavras-chave
Wilancookite, New mineral, Zeolite framework, Beryllophosphate
Citação
HATERT, F. et al. Wilancookite, (Ba,K,Na)8(Ba,Li,[])6Be24P24O96·32H2O, a new 2 beryllophosphate with a zeolite framework. European Journal of Mineralogy, v. 29, n. 5, p. 923-930, 2017. Disponível em: <https://www.schweizerbart.de/papers/ejm/detail/29/88299/Wilancookite_Ba_K_Na_8_Ba_Li__6_Be24_P24_O96_32H?af=crossref>. Acesso em: 25 ago. 2017.