Acta Musei Moraviae

Composition of vesuvianite from skarnoid from Moravské Bránice (Moravosilesian Zone)

Study of long-prismatic vesuvianite-group minerals from skarnoid at the locality Moravské Bránice using the electron microprobe and LA-ICP-MS (laser ablation mass spectrometry with inductively coupled plasma) provided new results on its chemical and trace-element composition. Four texturally-paragenetic types of vesuvianite were distinguished. Primary vesuvianite VES 1 occurs in the mineral assemblage Ves + Di + Ep whereas the primary vesuvianites VES 2 and VES 3 were found in the mineral assemblage Ves + Di + Grs; both assemblages contain accessory apatite, titanite, zircon and rare malayaite. Alteration of VES 2 results in Ca, Al, F-depleted hydrated mineral (VES 4) with composition that still resembles vesuvianite stoichiometry. The primary vesuvianite from Moravské Bránice is remarkable by its high Ti contents (up to 0.97 apfu; 2.62 wt.% TiO₂), and elevated Li (up to 157 ppm), Be (up to 90 ppm) and REE, Th, U amounts (up to 3100 ppm Ce, 1300 ppm Th, and 240 ppm U). Secondary alteration that removed part of Ca, Al, and F from VES 2 and increased B, Sr, REE, Th, and U contents in resulting VES 4 was most likely low-volume hydrothermal process. Vesuvianite stability during postmagmatic processes (recrystallization, alteration) makes it plausible tool for monitoring of postmagmatic processes.