1218 and interlayer/exchange processes. These mineralogical controls provide a mechanistic bridge between the composition of the Carajás mafic rocks, and the improvements observed in incubation and greenhouse trials. Figure 6 – Accumulation of potassium, calcium, and magnesium in the dry matter of corn and soybean grown for 45 days under greenhouse conditions in Red Latosol (LV) and Quartzipsamment (NQ) soils under increasing doses of fresh mafic rock and a reference limestone dose. (A) K accumulation in corn; (B) K accumulation in soybean; (C) Ca accumulation in corn; (D) Ca accumulation in soybean; (E) Mg accumulation in corn; (F) Mg accumulation in soybean. 5. CONCLUSIONS Fresh mafic rocks associated with iron ore deposits in Vale’s Serra Norte Mine exhibit chemical and mineralogical characteristics that comply with the legal specifications required for soil remineralizers. These lithologies—comprising basalts, diabase dikes, and unaltered gabbros—meet the established criteria for base cation content, K₂O concentration, quartz limits, and thresholds for potentially toxic elements. Complementary macroscopic, chemical, and mineralogical analyses confirmed the presence of two distinct rock types: (i) a basaltic volcanic mafic rock from the Parauapebas Formation and (ii) a younger plutonic rock of gabbro–diorite composition. Agronomic efficiency trials indicate promising results, demonstrating that these hydrothermally altered mafic rocks can be effectively used both for soil remineralization and for pH stabilization. Their potential applications include major crops such as soybean and corn, as well as pasture recovery and reforestation with native Amazonian species. Finally, mine sequencing plans for Serra Norte indicate that large volumes of these mafic lithologies—currently classified as waste—will become available in the coming years, reinforcing their
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