TY - JOUR A1 - Uher,P. A1 - Davidova,S. A1 - Vikar,I. T1 - Schorl composition from the barren granitic pegmatites in the Western Carpathians: Two examples from the Nizke Tatry mountains, Central Slovakia JF - Journal of the Czech Geological Society JA - J. Czech Geol. Soc. Y1 - 2001 VL - 46 IS - 1-2 SP - 21 EP - 26 CY - Prague PB - Czech Geological Society SN - 1803-1943 (online), 1802-6222 (print) AV - Free UR - http://www.jgeosci.org/index.php?pg=detail&ID=JCGS.815 L1 - http://www.jgeosci.org/content/JCGS2001_1-2__uher.pdf KW - schorl KW - tourmaline KW - barren granitic pegmatite KW - Nizke Tatry Mts. KW - Slovakia AB - Tourmaline group minerals belong to rather uncommon accessory minerals of the Hercynian granitic pegmatites of the Central Western Carpathians, Slovakia. Black tourmaline from two barren quartz-feldspar-(biotite-muscovite) pegmatites of the Nizke Tatry Mts.: Bystra Valley - Srdiecko (TBV) and Magurka - Adolf adit (TMA), were studied by EMPA. Both tourmalines show schorl compositions with intermediate X-site vacanies: 0.25-0.33 pfu, slight compositional zonality with increasing Fe/(Fe+Mg) ratio from center to rim of crystals, and low Ca and K contents. The most striking feature of the TMA schorl is a notably high Mn content: 0.98-1.56 wt. % MnO, 0.14-0.23 apfu, exceptional for schorl from poorly fractionated granite-pegmatite environment. Nevertheless, the TMA schorl also reveals higher Fe/(Fe+Mg) ratio in comparison to TBV: 0.69-0.83 and 0.54-0.60, respectively, and Mn values correlate positively with Fe, Fe/(Fe+Mg) and X-site vacancies. Thus, the elevated Mn content in TMA schorl is probably a consequence of local Mn-rich environment, probably due to absence of garnet as well as a relatively higher overall fractionation level. ER -