Greisen-Hosted Lithium Resources of the Erzgebirge/Krušné Hory Province (Germany and Czech Republic)

We present an overview of the geology, lithium resources, and exploration potential of greisen-hosted Li mica systems of the Erzgebirge/Krušné hory metallogenetic province, with emphasis on the Zinnwald-Cínovec deposit(s), the largest hard-rock Li resource in Europe (>1.9 million metric tonnes [Mt] of Li). In addition to Li, the greisen systems of the Erzgebirge/Krušné hory comprise significant resources of Sn and W with potential for some other critical metals such as Sc, Nb, and Ta. Lithium mineralization is related to hydrothermal alteration associated with late Paleozoic highly fractionated leucogranites, which are strongly enriched in Li, Sn, W, F, Rb, Cs, Nb, and Ta (rare metal granites). Metasedimentary protoliths of the granitic melts were invoked as the source of Li, which was then enriched by fractional crystallization. The high concentration of fluxes (F, Li, H2O) in the melts likely promoted protracted crystallization and undercooling of granitic melts. Further Li enrichment occurred at the magmatic-hydrothermal transition and during the early hydrothermal stage, which led to the formation of economically significant concentrations of Li associated with greisen and to a lesser extent sodic ± potassic alteration. Alteration affected the uppermost part of the granite stocks and their immediate wall rocks. The main host of Li is trioctahedral zinnwaldite, which is most abundant in endocontact greisen alteration zones. The regional accumulation of Li deposits/prospects in the eastern Erzgebirge/Krušné hory and the lack of such in the western part is likely due to the favorable level of exhumation relative to the emplacement depth of Li granites in the east, whereas the Li granites in the west are too deeply eroded to preserve their Li-enriched cupolas. Based on the current level of knowledge, the western Erzgebirge/Krušné hory has a lower potential for Li deposits, whereas the central and eastern parts have significant potential to expand the known resources.