Hydroxycalciopyrochlore from a regionally metamorphic marble at Bližná, Southwestern Czech Republic

0467978 - GLÚ 2018 RIV DE eng J - Článek v odborném periodiku
Drábek, M. - Frýda, J. - Šarbach, M. - Skála, Roman
Hydroxycalciopyrochlore from a regionally metamorphic marble at Bližná, Southwestern Czech Republic.
Neues Jahrbuch für Mineralogie. Abhandlungen. Roč. 194, č. 1 (2017), s. 49-59. ISSN 0077-7757. E-ISSN 0077-7757
Institucionální podpora: RVO:67985831
Klíčová slova: hydroxycalciopyrochlore * pyrochlore * carbonatite-like marble * marble * Moldanubian Varied Group
Obor OECD: Mineralogy
Impakt faktor: 0.614, rok: 2017

We describe an unusual occurrence of hydroxycalciopyrochlore in marble exposed in the Václav graphite mine at Bližná, southern Czech Republic. Roundish grains attain up to 3 cm, and euhedral crystals are up to 2 mm across. An empirical formula, calculated on the basis two B atoms per formula unit (pfu), is: (Ca_0.48Na_0.02Mg_0.06Mn_0.01Y_0.06.SIGMA.REEs_0.27Th_0.27U_0.01)_.SIGMA.1.12 (Nb_1.06Ti_0.79Fe_0.14W_0.01)_.SIGMA.2 (O_4.96OH_1.04)_.SIGMA.6(OH)_0.81•H₂O. The associated minerals, in addition to the rock-forming minerals calcite, phlogopite and edenite, include ilmenite, magnetite, euxenite, uranoan thorite, rutile, zircon, molybdenite, chalcopyrite, galena, sphalerite, pyrite, pyrrhotite, barite and apatite. This is the first occurrence of a pyrochlore-group mineral in regionally metamorphosed marble. The assemblage is considered to represent a metamorphosed carbonate-dominated sediment containing evaporitic horizons and volcanic detritus. Now give the reader an explanation, what makes it carbonatite-like?
Trvalý link: http://hdl.handle.net/11104/0265911