The increasing range of borate uses, mainly in the ceramic frit market, led borate producers to improve competitiveness through concentration and/or purification steps in the mill circuit as well as in the characterization of high content B2O3 minerals. Minerals coming from Sijes, Salta Province, Argentina, mainly identified as colemanite and hydroboracite, with 50.84 % and 50.54 % B2O3 respectively, are potentially interesting from an industrial point of view. The desliming purification technique in hydrocyclones used to upgrade B2O3 and downgrade undesirable impurities to the borate market (Rietveld method) mainly iron oxides, chlorides and sulphates) not only eliminates slimes but it also generates pores, through a decrease of the specific surface of the particles. Two samples under different purification steps were analyzed: deslimed and without desliming. The chemical and mineralogical analyses of both samples indicate a decreasing percentage of colemanite, smectite and illite in the deslimed sample with a small increase of hibroracite. The parameters of surface electric charge (PZC and IEP) match the observations made with the electronic microscopy, reveal mineral associations only in the sample without desliming.