Bauxite are the major aluminum ores, are formed by intense weathering of different rock
types and very common in tropical regions such as the Amazon. Different researchers have
worked on this subject, whose genesis and complex structure of the profiles is still very
controversial issue. In the state of Pará, the province bauxitífera Paragominas is the latest
producing region after region of Trombetas. In structuring the profile of this region,
superimposed on the main bauxite horizon (BC – Crystallized Bauxite), there is a horizon of
Nodular Bauxite (BN). This has proportionally high content of kaolinite, harmful to the
metallurgical process for obtaining alumina. This study characterized the different horizons
through chemical analysis and mineralogical Fluorescence and X-ray diffraction, and
petrographic description / texture in order to recognize the structural and textural influences
the genesis and development of the profiles. Were selected three bauxitic profiles of Vera
Cruz area, city of Paragominas, a total of 30 samples. The results revealed a high
concentration of kaolinite and consequently high content of reactive silica (SiO2_R) and low
alumina contents usable in most of BA, BCBA, LF, BN BNC horizons, and good values of
these parameters for most samples the Horizon BC . The mineralogy has high levels of
gibbsite (main ore/mineral-Al) with different “degrees of crystallinity” in addition to
kaolinite, goethite (mainly aluminous), hematite, anatase and quartz in different proportions,
depending on the horizon. Different images and schematic representations of the textures
were obtained in order to assist the understanding of the formation and development of
horizons within the profile. It is concluded that the origin and development of the profiles
occurred in a complex and polyphasic ways, given its structure, petrographic-textutal
characteristics and irregular geographic distribution, which had confirmed Costa (1984) and
Kotschoubey et al (2005) models. Another important finding was the strong influence climate
and the occurrence of at least two bauxitization cycles, temporally well marked, the first in the
Eocene or early Oligocene and the second in late Oligocene or early Miocene.
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