Acta Musei Moraviae

Mineralogy, petrography and history of the classical lepidolite pegmatite occurrence in Rožná near Bystrice nad Pernštejnem, western Moravia; an overview

The Rožná pegmatite, a classical Moravian locality studied from the 18th century, is located in the north – easternmost part of the Strážek Moldanubicum, along the contact with the Svratka Unit, and it is hosted in migmatized biotite gneiss . The pegmatite dike, about 1 km long and about 35 m wide, is NNW-trending and dips about 60 °ENE. The Rožná pegmatite was opened on the Hradisko hill, the classical part of the dike studied from the 18th century, on the Borovina hill and in locality Rožná-north . Internal structure of the Rožná pegmatite is close to symmetric, consisting of the textural-paragenetic units: (i) biotite-bearing wall zone; (ii) schorl-bearing intermediate zone with blocks of (iii) graphic unit and masses (veins?) of (iv) granitic unit; relatively rare (v) K-feldspar from blocky core-margin zone and (vi) quartz core surrounded and in part penetrated by (vii) albite-lepidolite complex. Late fracture-filling tourmaline veins were found particularly in the (ii), (iii) and (iv) units. The most abundant minerals include quartz, K-feldspars and albite. Micas (biotite, muscovite, lepidolite) and tourmaline (schorl, foitite, elbaite, rossmanite, dravite) are typical subordinate minerals present in almost all textural-paragenetic units. Cassiterite, fluorapatite, amblygonite-montebrasite, columbite-tantalite, triplite, topaz, and beryl are typical minor to accessory minerals, zircon, ixiolite, monazite-(Ce) and almandine-spessartine are very rare. Hydrothermal minerals include hydroxylherderite, bertrandite, lacroixite, brasilianite, goyazite, eosphorite, pyrite, haematite, kaolinite, chalcedony and opal. Internal structure, mineralogy, chemistry of minerals and compositional trends indicate that the Rožná lepidolite pegmatite is the largest complex pegmatite in the Moldanubicum and it is very similar to the lepidolite pegmatites in Varutrásk in Sweden and Brown Derby in Colorado, USA.