Oxy-schorl, Na(Fe.sup.2+./sup..sub.2./sub.Al)Al.sub.6./sub.Si.sub.6./sub.O.sub.18./sub.(BO.sub.3./sub.).sub.3./sub.(OH).sub.3./sub.O, a new mineral from Zlatá Idka, Slovak Republic and Přibyslavice, Czech Republic

0389392 - GLÚ 2013 RIV US eng J - Journal Article
Bačík, P. - Cempírek, J. - Uher, P. - Novák, M. - Ozdín, D. - Filip, J. - Škoda, R. - Breiter, Karel - Klementová, Mariana - Ďuďa, R. - Groat, L. A.
Oxy-schorl, Na(Fe²⁺₂Al)Al₆Si₆O₁₈(BO₃)₃(OH)₃O, a new mineral from Zlatá Idka, Slovak Republic and Přibyslavice, Czech Republic.
American Mineralogist. Roč. 98, 2/3 (2013), s. 485-492. ISSN 0003-004X. E-ISSN 1945-3027
Institutional support: RVO:67985831 ; RVO:68378271
Keywords : Oxy-schorl * tourmaline-supergroup minerals * new mineral * electron microanalysis * crystal-structure refinement * Přibyslavice * Zlatá Idka
Subject RIV: DB - Geology ; Mineralogy
Impact factor: 2.059, year: 2013

Oxy-schorl, Na(Fe²⁺₂Al)Al₆Si₆O₁₈(BO₃)₃(OH)₃O, is a new mineral species of the tourmaline group and it was found on two localities – Přibyslavice, Czech Republic and co-type locality Zlatá Idka, Slovak Republic. Oxy-schorl from Přibyslavice occurs in a foliated muscovite-tourmaline orthogneiss with associated minerals including K-feldspar (orthoclase-perthite), albite, quartz, muscovite, biotite, apatite and garnet. Oxy-schorl from Zlatá Idka occurs in extensively metasomatically altered Silurian metarhyolite pyroclastics with muscovite, quartz, and albite. Oxy-schorl from Přibyslavice forms abundant brownish black subhedral, columnar crystals, up to 1 cm in size, arranged in thin layers, or irregular clusters up to 5 cm in diameter in muscovite-tourmaline orthogneiss. Oxy-schorl from Zlatá Idka forms fan-shaped aggregates of greenish black acicular crystals ranging up to 2 cm in size, with aggregates up to 3.5 cm across. Oxy-schorl has a brown (Přibyslavice) to pale grey (Zlatá Idka) streak. Oxy-schorl from both localities is brittle and has a Mohs hardness of ca 7. It has no observable cleavage and parting. Oxy-schorl has a measured density of 3.19 g/cm (Přibyslavice) and 3.17 g/cm (Zlatá Idka) using pycnometry and calculated density of 3.198 g/cm (Přibyslavice), 3.208 g/cm (Zlatá Idka) using empirical formulae and separate unit cell data. In plane polarized light, it is pleochroic, O = dark greyish-green (Přibyslavice) and green to bluish-green (Zlatá Idka), E = pale brown (Přibyslavice) and pale yellowish to nearly colorless (Zlatá Idka). Oxy-schorl is uniaxial negative. Oxy-schorl is trigonal, space group R3m, a = 15.9853(12) Å, c = 7.1538(6) Å, V = 1583.1(2) Å3, Z = 3.
Permanent Link: http://hdl.handle.net/11104/0218265