Classification of rare earths mineral resources using the Jequié/BA complex rock weathering chemical index

Abstract

The most common economic mineral deposits of Rare Earths are associated to magmatic calc-alkaline to alkaline rocks and their products. This work presents data from drilling carried out in rocks of the Jequié/BA Complex, mineralized in rare earths, which were subjected to an intense weathering process, similar to what occurred in the Ion Adsorption Clays deposits in southern China. The interpretation of the survey data allowed the classification of rare earths mineral resources with similar, sometimes higher, levels than those of Chinese deposits, contained in the lateritic regolithic profile studied. The chemical index of rock alteration (CIA) was adopted as a classification tool, horizontally separating the mineralized weather profile into six zones. The data indicate that there was supergenic enrichment REO in the lower portions of the profile and sometimes in the upper zones. The average levels ranged between 0.09% and 0.22% REO, with maximum values of 1.6%. A model section representing the deposit of rare earths minerals of supergenic origin in rocks of the Jequié/BA Complex was developed.