Lithium-bearing phosphates and micas in Homolka leucogranite

Homolka granite forms intrusion of highly fractionated leucocratic magma which belongs to the youngest members of the Moldanubian Pluton. The age of the intrusion was estimated between 319 and 315 Ma. The Homolka granite is P-rich, peraluminous and strongly enriched in Li, Rb, Cs, Sn, Nb, Ta and F, showing high U (8–20 ppm) and low Th (< 3 ppm) contents. This study focuses on Li-bearing minerals – phosphates and white micas. Their modal proportions correspond to 1–3 vol. % and 5–15 vol. %, respectively. Both mineral groups occur in several generations in the rock. The first phosphate generation (for example, Al-bearing montebrasite or Fe-Mn-bearing triphylite) contains up to 11 wt. % Li2O. The first generation of mica (Li-phengite) contains about 7–8 wt. % F and up to 1 wt. % Rb2O with Li2O content ranging between 1.3 and 1.9 wt. %. The second generation of white mica, replacing Li-phengite, is depleted in F and Rb and shows decrease in Li2O to 0.5–0.9 wt. %. Despite the low total content of lithium (Li2O = about 0.1 wt. %) in the rock, the occurrence of the leucocratic Homolka granite is not negligible. Because of the high economic potential of lithium, these highly evolved peraluminous and lithium-bearing intrusions will deserve a special attention in the future.