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IMA 2017-099 = ferrierite-NH4 (no replies)

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Reference:
▪ Chukanov, N.V., Pekov, I.V., Sejkora, J., Plášil, J., Belakovskiy, D.I., Britvin, S.N. (2019): Ferrierite-NH4, (NH4,Mg0.5)5(Al5Si31O72)·22H2O, A New Zeolite From Northern Bohemia, Czech Republic. [i]Canadian Mineralogist[/i],[b] 57[/b], 81-90.

Abstract:
The new zeolite ferrierite-NH4, ideally (NH4,Mg0.5)5(Al5Si31O72)·22H2O, was discovered in open pits at Libouš and Bílína in the Miocene Most Basin, which is situated in the Czech Republic. The associated minerals are calcite, siderite, whewellite, quartz, opal, baryte, and clay minerals (at Libouš) and marcasite, pyrite, baryte, sphalerite, and gypsum (at Bílína). Ferrierite-NH4 forms white radiating aggregates up to 2 mm across consisting of thin flattened prismatic crystals. Density calculated from the empirical formula is 2.154 g/cm3. Ferrierite-NH4 is optically biaxial, positive, α = 1.518(2), β = 1.520(2), γ = 1.522(2) (λ = 589 nm). The IR spectrum shows the presence of the NH4+ cation. The chemical composition of the holotype sample is (wt.%; electron microprobe, H and N analyzed by gas chromatography of products of ignition): (NH4)2O 2.7, Na2O 0.24, MgO 1.63, Al2O3 10.48, SiO2 69.44, H2O 14.8, total 99.29. The empirical formula based on 36 Si+Al pfu is H0.35[(NH4)2.74Mg1.07Na0.21](Al5.44Si30.56O72)·21.55H2O. Ferrierite-NH4 is orthorhombic, space group Immm, with a 19.10(1) Å, b 14.15(1) Å, c 7.489(3) Å, V 2024(3) Å3, and Z = 1. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 9.52 (97) (200), 6.95 (28) (101), 6.60 (19) (011), 3.988 (61) (321, 031, 420), 3.784 (19) (330), 3.547 (73) (112, 040), 3.482 (100) (202), 3.143 (37) (141, 312).

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