Chemical composition of the betafite, ilmenite, rutile and rhabdophan of the W-Mo-bearing «Badillo» deposit, Angulos, Argentina

Abstract

The «Badillo» deposit, located in the central-east sector of the Famatina System, is formed of small quartz-lenses which are cavity fillings (fissures and fractures) in a host-rock whose mineralogy is essentially wolframite, scheelite and molybdenite. The deposit is spatially and genetically related to the Potrerillos leucogranite which has an important muscovite alteration, locally related to the mineralization. Betafite, ilmenite, rutile and rhabdophane are accessory minerals in the mineralogy of the «Badillo» deposit and all are of microscopic size. Although mentioned in earlier literature, no detailed compositional and and minero-chemical study had previously been carried out. The betafite belongs to a uranium and calcium titanate-niobiate of the pyroclore group, with scarce tantalium. The manganese concentration in the ilmenite is high (7.14 % MnO), while the rutile associated with the biotite in the Potrerillos granite, formed during post-magmatic alteration, recorded up to 7.14 % WO₃, and the rutile in the quartz lenses up to 7.92 % Nb₂O₅. These values are than higher than reported by other authors for the same minerals in different Argentine ore-deposits. Finally, the phosphate-bearing light rare earths and thorium belong to rhabdophane.