Garnet composition from the Reflejos de Mar LCT-pegmatite, Ancasti district, Argentina and its implication for exploration of primary deposits of lithium

The Reflejos de Mar Li-pegmatite, located in northwestern Argentina, is part of the Villismán pegmatite group, Ancasti District, Pampean Pegmatite Province. Four garnet crystals from outermost were analyzed by major and minor elements (SiO2, TiO2, Al2O3, Cr2O3, MgO, CaO, MnO, FeO) using electron microprobe. belongs to rare-element class, spodumene type, LCT (Li-Cs-Ta) petrogenetic family. Based on their Mn Fe contents, can be assigned spessartine-almandine serie. cores rims garnets show significant differences for divalent components VIII-coordination, especially, Fe. average MnO FeO contents grains 34.6 8.29 wt%, respectively, while 29.31 12.95 respectively. Fe/Mn ratio at core 0.24 it 0.44. Cr2O3 TiO2 are very low (˂0.17 wt%) values SiO2 Al2O3 ~36 ~21 mean chemical molecular formulas expressed: [(Mn2.40 Fe0.57 Ca0.02 Mg0.02)3.01 (Al1.99 Cr0.002)2.00 (Si2.99 Ti0.01)3.00 O12]; {Sps79.8 Alm18.9 Grs0.7 Prp0.5}; rim as: [(Mn2.04 Fe0.89 Ca0.05 Mg0.04)3.02 (Al2.00 (Si2.98 Ti0.005)3.00 {Sps67.6 Alm29.5 Grs1.6 Prp1.3}. composition similar other worldwide examples rocks, especially pegmatites, which highly evolved associated with Li mineralization. Therefore, its could used as an additional tool exploration Li-bearing pegmatites Fe-Mn between would controlled variations pegmatitic melt and, addition, simultaneous precipitation mineral phases, example, schorl Mn-Fe-bearing phosphates.