New data on ferriakasakaite-(La) and related minerals extending the compositional field of the epidote supergroup

Chukanov, N.V.; Zubkova, N.V.; Schäfer, C.; Varlamov, D.A.; Ermolaeva, V.N.; Polekhovsky, Y.S.; Jančev, S.; Pekov, I.V.; Pushcharovsky, D.Y.

Авторы: Chukanov N.V., Zubkova N.V., Schäfer C., Varlamov D.A., Ermolaeva V.N., Polekhovsky Yu S., Jančev S., Pekov I.V., Pushcharovsky D.Yu
Журнал: European Journal of Mineralogy
Том: 30
Номер: 2
Год издания: 2018
Издательство: E. Schweizerbart'sche Verlagsbuchhandlung
Местоположение издательства: Germany
Первая страница: 323
Последняя страница: 332
DOI: 10.1127/ejm/2018/0030-2716
Аннотация: Detailed studies of ferriakasakaite-(La) including determination of chemical composition and crystal structure, infrared spectroscopy, optical characteristics in reflected light and micro-indentation hardness have been carried out on a non-metamict sample from young nosean-bearing sanidinite from the Laach lake volcanic complex, Eifel, Germany. The chemical composition is (electron microprobe, Fe2+ : Fe3+ determined from structural data, wt.%): CaO 6.74, La2O3 13.35, Ce2O3 10.58, Pr2O3 0.42, Nd2O3 0.49, Sm2O3, 0.34, Eu2O3 0.18, Gd2O3 0.20, ThO2 0.43, UO2 0.10, MgO 0.89, MnO 9.98, Al2O3 11.47, Fe2O3 7.39, FeO 4.04, TiO2 1.32, SiO2 29.80, H2O (calc.) 1.49, total 99.22. The empirical formula is (Ca0.68Mn2+0.32)1.00(La0.49Ce0.39Pr0.02Nd0.02Sm0.01Eu0.01Gd0.01Th0.01Ca0.04)1.00 (Fe3+0.56Al0.34Ti0.10)1.00Al1.00(Mn2+0.53Fe2+0.34Mg0.13)1.00(Si2.98Al0.02)3.00O12.02(OH). The crystal structure was solved by direct methods and refined to R = 0.0182 for 1259 unique reflections with I > 2(I). The H atom was located. The mineral is monoclinic, space group P21/m, a = 8.90540(13), b = 5.75454(7), c = 10.10367(15) Å,  = 114.1030(18) V = 472.634(11) Å3. The IR spectrum confirms the presence of OH groups. Reflectance spectra of ferriakasakaite-(La) obtained in visible range show reflectance minima at the wavelength about 590 nm. Epidote-supergroup minerals ferriakasakaite-(La), allanite-(Ce), Al-dominant (at the M1 site) analogue of ferriakasakaite-(Ce), piemontite, piemontite-(Pb), and Fe3+-dominant (at the M1 site) analogues of piemontite and piemontite-(Pb), including their Pb-, Zn- and Cu-bearing varieties have been discovered in sulfide-free metasomatic rocks, containing oxygen compounds of chalcophile elements (Zn, Cu, Sb, and Pb), within the Pelagonian massif, Republic of Macedonia. Crystal chemical features of these minerals are discussed.
Добавил в систему: Ермолаева Вера Никитична

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New data on ferriakasakaite-(La) and related minerals extending the compositional field of the epidote supergroupстатья Исследовательская статья

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