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@article{1509276,
author = {Ondrejka, Martin and Bacik, Peter and Sobocky, Tomáš and Uher, Pavel and Škoda, Radek and Mikus, Tomáš and Luptakova, Jarmila and Konecny, Pavel},
article_location = {Middlesex},
article_number = {6},
doi = {http://dx.doi.org/10.1180/mgm.2018.137},
keywords = {rhabdophane group; alunite supergroup; jarosite; alunite; corkite; hinsdalite; supergene alteration; microgranite; Velence; Hungary},
language = {eng},
issn = {0026-461X},
journal = {Mineralogical Magazine},
title = {Minerals of the rhabdophane group and the alunite supergroup in microgranite: products of low-temperature alteration in a highly acidic environment from the Velence Hills, Hungary},
url = {http://dx.doi.org/10.1180/mgm.2018.137},
volume = {82},
year = {2018}
}
TY - JOUR
ID - 1509276
AU - Ondrejka, Martin - Bacik, Peter - Sobocky, Tomáš - Uher, Pavel - Škoda, Radek - Mikus, Tomáš - Luptakova, Jarmila - Konecny, Pavel
PY - 2018
TI - Minerals of the rhabdophane group and the alunite supergroup in microgranite: products of low-temperature alteration in a highly acidic environment from the Velence Hills, Hungary
JF - Mineralogical Magazine
VL - 82
IS - 6
SP - 1277-1300
EP - 1277-1300
PB - Mineralogical Society
SN - 0026461X
KW - rhabdophane group
KW - alunite supergroup
KW - jarosite
KW - alunite
KW - corkite
KW - hinsdalite
KW - supergene alteration
KW - microgranite
KW - Velence
KW - Hungary
UR - http://dx.doi.org/10.1180/mgm.2018.137
N2 - An assemblage of alunite-supergroup minerals (ASM), rhabdophane-group minerals (RGM), goethite and associated clay minerals occurs in Permian A-type porphyritic microgranite in the eastern part of the Velence Hills, Hungary. The secondary sulfates/phosphates include jarosite, Pb-rich jamsite and alunite, corkite, hinsdalite and rhabdophane-(Ce), -(La) and -(Nd). Detailed electron probe microanalysis and Raman spectroscopy reveal a wide miscibility among RGM end-members and show a rhabdophane- tristramite-brockite solid solution with extensive compositional variation. Moreover, ASM show heterogeneous composition and complex substitution mechanisms within the alunite, beudantite and plumbogummite groups. The formation of this rare mineral assemblage reveals extensive remobilization of rare-earth elements (REE), Th, U, P, S, Fe and Pb under supergene conditions. Compositional variations and substitution trends of the RGM investigated indicate that Th, U, Ca and Pb are incorporated into the rhabdophane structure by a (Ca, Pb)(2+) + (Th, U)(4+) <--> 2REE(3+) substitution mechanism. Consequently, we suggest the following end-member formulae for RGM containing divalent and tetravalent cations: (Ca0.5Th0.5)PO4 center dot H2O for brockite, (Pb0.5Th0.5)PO4 center dot H2O for grayite and (Ca0.5U0.5)PO4 center dot H2O for tristramite. The ASM and RGM originated from total leaching of the primary magmatic REE, Th, U and P minerals in the microgranite [most probably allanite-(Ce), fluorapatite and possibly also xenotime-(Y)]. together with input of Pb and S in low-temperature, acid sulfate solutions, connected with an adjacent Palaeogene andesite-diorite intrusion and the accompanying hydrothermal sulfide mineralization.
ER -
ONDREJKA, Martin, Peter BACIK, Tomáš SOBOCKY, Pavel UHER, Radek ŠKODA, Tomáš MIKUS, Jarmila LUPTAKOVA a Pavel KONECNY. Minerals of the rhabdophane group and the alunite supergroup in microgranite: products of low-temperature alteration in a highly acidic environment from the Velence Hills, Hungary. \textit{Mineralogical Magazine}. Middlesex: Mineralogical Society, 2018, roč.~82, č.~6, s.~1277-1300. ISSN~0026-461X. Dostupné z: https://dx.doi.org/10.1180/mgm.2018.137.
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