The potential of lithium in alkali feldspars, quartz, and muscovite as a geochemical indicator in the exploration for lithium-rich granitic pegmatites: A case study from the spodumene-rich Moblan pegmatite, Quebec, Canada

The Li concentration of alkali feldspars, quartz, and muscovite from the spodumene-rich Main Sill of the Moblan pegmatite in Quebec, Canada, was used to evaluate the potential of the most common minerals in granitic pegmatites as indicators for the presence of Li-aluminosilicate mineralization. In Moblan, alkali feldspar crystals incorporate 9-350 ppm Li, with the higher concentrations measured in samples lacking spodumene and muscovite. The observed trend in Moblan is particularly useful in cases where outcrop exposure to the surface is limited and the presence of Li-aluminosilicate minerals cannot be used for a preliminary assessment of the economic potential of a pegmatite. The Li concentration of quartz in Moblan is also elevated, ranging between 9 and 365 ppm. Muscovite crystals show the highest Li concentrations, incorporating between 562 and 6710 ppm. No consistent trends were observed in the distribution of Li in quartz and muscovite regarding their vicinity to spodumene or the zones from which they were derived. The Li concentrations of alkali feldspar, quartz and muscovite in Moblan are consistently higher than those measured in Li-poor and potentially barren pegmatites; the geochemical signature of these common minerals thus provides a useful exploration tool, independent of outcrop exposure, for the identification of Li-rich targets.