Acta Musei Moraviae

Mineralogy of quartz-hematite vein with amethyst from the locality “Na Dolečkách” in Bludov near Šumperk

Results of mineralogical study of quartz-hematite vein with local amethyst occurrence from the locality “Na Dolečkách” in Bludov near Šumperk are presented. The main vein with thickness up to 1 m is over 1 km long with NW-SE orientation. Older stage of white-grey quartz without hematite is developed as asymmetric zone in some veins. Hematite (specularite variety) is presented in younger quartz-hematite vein stage with symmetric development. The mentioned two quartz stages are good visible in breccia like textures and in CL-study. Boundary of quartz veins with altered granodiorite is sharp. Hematite – specularite has simple composition with trace elements: Ti (up to 1.68 wt.% TiO₂), V (up to 0.49 wt.% V₂O₃) and Al (up to 0.52 wt.% Al₂O₃). Needle like hematite inclusions with parallel arrangement were identified in amethyst crystals by Raman spectroscopy. On the base of textures, hematite morphology and chemistry, origin of quartzhematite stage of vein is interpreted as low-temperature hydrothermal, near so called „Alpine paragenesis“ in acidic rock environment.