2020
Fluorapophyllite-(NH4), NH4Ca4(Si8O20)F center dot 8H(2)O, a new member of the apophyllite group from the Vechec quarry, eastern Slovakia
ŠTEVKO, Martin; Jiří SEJKORA; Jakub PLÁŠIL; Zdeněk DOLNÍČEK; Radek ŠKODA et. al.Základní údaje
Originální název
Fluorapophyllite-(NH4), NH4Ca4(Si8O20)F center dot 8H(2)O, a new member of the apophyllite group from the Vechec quarry, eastern Slovakia
Autoři
ŠTEVKO, Martin; Jiří SEJKORA; Jakub PLÁŠIL; Zdeněk DOLNÍČEK a Radek ŠKODA
Vydání
Mineralogical Magazine, Middlesex, Mineralogical Society, 2020, 0026-461X
Další údaje
Jazyk
angličtina
Typ výsledku
Článek v odborném periodiku
Obor
10504 Mineralogy
Stát vydavatele
Velká Británie a Severní Irsko
Utajení
není předmětem státního či obchodního tajemství
Odkazy
Impakt faktor
Impact factor: 2.062
Kód RIV
RIV/00216224:14310/20:00117569
Organizační jednotka
Přírodovědecká fakulta
UT WoS
000566874000005
EID Scopus
2-s2.0-85091454778
Klíčová slova anglicky
fluorapophyllite-(NH4); new mineral; apophyllite group; phyllosilicates; Raman spectroscopy; xenoliths; Vechec; Slovakia
Příznaky
Mezinárodní význam, Recenzováno
Změněno: 5. 1. 2021 15:01, Mgr. Marie Novosadová Šípková, DiS.
Anotace
V originále
The new mineral fluorapophyllite-(NH4), ideally NH4Ca4(Si8O20)F center dot 8H(2)O, was found at the Vechec andesite quarry located near Vechec village, Vranov nad Topl'ou Co., Pregov Region, Slovak Republic. It occurs in cavities of quartz-illite-saponite-tobelite xenolith embedded in pyroxene andesite. Fluorapophyllite-(NH4) is associated with calcite, tridymite, pyrite, chabazite-Ca and heulandite-Ca. It forms clusters, aggregates or crystalline crusts consisting of individual, well-developed crystals up to 4 mm in size, exhibiting the forms {110}, {101} and {001}. The mineral is colourless to light pink and translucent with white streak and vitreous to pearly lustre; it is nonfluorescent under ultraviolet radiation. The Mohs hardness is similar to 4% to 5, tenacity is brittle, fracture is irregular, and there is perfect cleavage on {001}. The calculated density is 2.325 g cm(-3). Fluorapophyllite-(NH4) is optically uniaxial (+) with omega = 1.5414(5) and epsilon = 1.5393(8) (lambda = 589 nm). It is non-pleochroic. The empirical formula (based on 29 O + F apfu) is [(NH4)(0.55)K0.32Na0.07Ca0.06](Sigma 1.00)(Ca4.01Mg0.02)(Sigma 4.03) Si7.97O20[F-0.84(OH)(0.16)](Sigma 1.00)center dot 8H(2)O. Fluorapophyllite-(NH4) is tetragonal, space group P4/mnc, a = 8.99336(9) angstrom, c = 15.7910(3) angstrom, V= 1277.18(3) angstrom(3) and Z = 2. The seven strongest X-ray powder diffraction lines are [d(obs) in angstrom,(I,%)(hkl)1: 7.897(32)(002), 7.812(13) (101), 4.547(14)(103), 3.946(100)(004), 2.985(39)(105), 2.4841(11)(215) and 1.5788(12)(00.10). The crystal structure of fluorapophyllite-(NH4), refined to R-1 = 0.0299 for 743 unique (I > 3 sigma I) observed reflections, confirmed that the atomic arrangement is very similar to that of the other members of the apophyllite group. The new mineral is named according to the current nomenclature scheme for apophyllite-group minerals and is an NH4 dominant analogue of fluorapophyllite-(K), fluorapophyllite-(Na) and fluorapophyllite-(Cs).