Tourmalines of the Velence Granite Formation and the surrounding contact slate, Velence Mountains, Hungary

Abstract Three distinct paragenetic and compositional types of tourmaline were described from the Velence Granite surrounding contact slate. Rare, pitch-black, disseminated I (intragranitic tourmaline) occurs in granite, pegmatite, aplite; very rare, black to greenish-gray, euhedral II (miarolitic miarolitic cavities pegmatites; abundant, gray, brown yellow or even colorless, acicular III (metasomatic slate its quartz-tourmaline veins. Tourmaline a variety environments exhibits considerable variation composition, which is controlled by nature host rock formation processes. However, similar geologic situations, composition can be rather uniform, between relatively distant localities. represented an Al-deficient, Fe 3+ -bearing schorl, crystallized closed melt-aqueous fluid system. schorl-elbaite mixed crystal, precipitated Li- F-enriched solutions pegmatites. shows oscillatory zoning; corresponds dravite, foitite species. It formed metasomatizing fluids derived granite. This most abundant type, found around