Fig. 2 and Fig. 3 present typical XRD patterns of the oriented < 2 μm. The presence of the kaolin mineral was detected by their d001 and d002 reflections centred at 7.10–7.21 Å and 3.58 Å. At Lapa Grande the XRD pattern ( Fig. 2a) Linsitinib quite different from Cerdeirinha ( Fig. 2c), being less sharp and intense for the Cerdeirinha samples, indicating an increasing disorder ( Brindley, 1980). In Penedono, kaolin mineral is characterized by sharp basal peaks (d001 and d002) at 7.18 Å and 3.58 Å ( Fig. 3a). Besides, the 001 reflection has a slight asymmetry at the low-angle side. Comparing the 00 l and hk indices and respective d values of the studied XRD patterns with data for halloysite from Brindley (1980), the kaolin mineral can be ascribed to halloysite(7 Å). In fact, regarding the random XRD pattern in Fig. 3c, the 00 l peaks are life history relatively weak, and the non-basal reflections (hk indices) are strong at about 20°2θ and 35°2θ ( Moore and Reynolds, 1997).