Apatite, of composition Ca5(PO4)3(F, Cl, OH), is one of the most common accessory minerals in magmatic rocks due to its wide stability to geological processes and carries in its structure a variety of minor and trace elements that can provide important informations. Understanding the morphological and geochemical signature of this mineral implies understanding its crystallization trajectory and the conditions that reigned during its formation. The work developed involved the morphological, textural and compositional study through MEV-EDS of apatite crystals present in the different facies of the tin-bearing granite Velho Guilherme, of reduced character, located in the Rio Maria Domain and part of the Província Estanífera do Sul do Pará, as well as apatites from the Central granite, locally containing quartz veins with occurrences of cassiterite, and located in the Carajás Domain. For comparative purposes, data obtained from previous work on apatites from the Bom Jardim and Antônio Vicente tin-bearing granites, also part of the Província Estanífera do Sul do Pará, and the barren granites Jamon and Redenção, which are more oxidized and belong to the Jamon Suite, were used; apatites from the Archean rocks of the Sanukitoide Rio Maria Suite and the Trondhjemito Mogno were also used, both included in the Rio Maria Domain. The compositional study demonstrated that the apatites from the Velho Guilherme and Central granites have higher contents of Y, La and Ce and lower contents of Ca+P in relation to the apatites found in granites devoid of mineralization and show a geochemical signature similar to the other apatites from tin-bearing granites from the Amazon Craton. Paleoproterozoic granites, both mineralized and barren, have apatites more enriched in ETR+Y than apatites from Archean rocks. Thus, MEV-EDS analysis, when used with due care, can satisfactorily assist in the study of minerals that are indicators of this type of mineralization, in addition to differentiating changes in the geological scenario of a given region during its crustal evolution, distinguishing, for example, Archean and Paleoproterozoic events.
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