Mineralogy and petrograghy of some tin, lithium and beryllium bearing albite-pegmatites near Doade, Galicia, Spain

The petrography and mineralogy of some Hercynian albite-pegmatites near Doade, Galicia, Spain is described. The mineral assemblage consists of albite, K-feldspar, quartz, muscovite, spodumene, petalite, cassiterite, beryl, columbitetantalite, montebrasite, apatite, eosphorite-childrenite, zircon, tourmaline, garnet, pyrite, bertrandite, ferrisicklerite, heterosite and cookeite. A tentative paragenetical sequence of these minerals is given. From the relationships between petalite and spodumene approximate initial temperature-pressure conditions of 600°C. and 2,5—3,5 kb. can be derived. The possible cause of the high sodium content and of the fine grainsize of the bulk of the pegmatites is discussed. A genetical relationship of the pegmatites with the medium to coarse grained Hercynian two-mica granites is suggested.