Late Paleozoic fluorine-rich granites and their host metasediments in the Emuford district of the Herberton tin field contain small zones of intense albitization that host cassiterite min-eralization. Sodium metasomatism was accompanied by hydrothermal leaching of granite quartz to form vuggy albite rocks (episyenites). Vugs created by quartz dissolution were filled in by hydrothermal minerals, including albite, K feldspar, and/or muscovite and cassiterite; late phases are dominated by quartz and fluorite. Swarms of parallel veinlets crosscut the albitized zones. These veinlets were formed by repeated fracturing in response to local fluid over-pressures. They contain infill mineralogy similar to the vugs and probably formed at least partly contemporaneously with vug infill. Due to the overprinting at various scales of alteration, vug infill, and vein formation stages, chemical changes associated with episyenite formation are only qualitatively constrained. However, the mineralogical and textural features of the alteration zones suggest that most major and trace elements had substantial mobility during their formation. Major chemical changes associated with episyenite formation include leaching of SiO2, K20, Rb, and Ba, with
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Charoy et al. (1989) studied this question.