The Tertiary volcano of the Macau Formation, related to the last magmatic pulses of the Borborema Province in the states of Paraíba and Rio Grande do Norte, manifested itself in the forms of plugs, dikes, veins, piroclasts and fissural flows. In the municipalities of Boa Vista, Sossego, Barra de Santa Rosa and Olivedos, the volcanic protoliths are arranged in the form of fissural flows of amoeboidal architecture, subjected to intense chemical weathering, evolving into calcium bentonite clays of the Campos Novos type, mined in the open pit. Boa Vista is the municipality that has the main bentonite deposits, with the occurrence of fossilized tree trunks; In Sossego, pockets of chalcedony are carved together with the bentonites; In Barra de Santa Rosa, the quantification of the deposits is in the conclusive phase of research. In Olivedos, the main bentonite mining takes place on the Campos de Baixo farm by Mineradora Meira de Melo. The open pit is constantly evolving, currently with a depth of more than 6 meters, where it was possible to establish on the main slope of the mine, a lithostratigraphic column consisting from the top to the base of soil, high Ti basalt, high Ti tuff, red bentonite, cream bentonite and white bentonite. The alteration products were submitted to expandability tests when submerged in water, petrographic analysis and geochemical analysis by X-ray Fluorescence (XRF), with the objective of contributing to the genetic knowledge through the geochemical composition and ionic mobility in the weathering profile. The results indicated that the mobility of the iron and manganese oxides-hydroxides, with impoverishment from the top to the bottom of the profile, were the main responsible for the change in the shade of the bentonites. White bentonite is essentially carbonate, with extremely high Ca values, around 83.76%, of zero expansion, with the presence of calcite. This factor, associated with the very low levels of SiO2, Al2O3 and Fe2O3, make the white bentonites distinguishable from the others, with special characteristics for the manufacturing industry. Trace elements and incompatible elements occur variably along the weathering profile, and are sometimes completely leached into the more evolved bentonites. The results obtained are considered preliminary, since they are part of the set of data related to the Doctoral Thesis being prepared by the first author at the Federal University of Campina Grande.