The Southeastern System mines are located in the Quadrilatero Femfero (Iron Quadrangle).

Ore reserves with high ratios of itabirite ore relative to hematite ore type. Itabirite ore has iron grade of 35-60%.

The Itabira complex is located in the northeastern corner of the Quadrilatero Femfero (Iron Quadrangle). It is enclosed by a local geologic structure that appears separated from the regional Iron Formation. The geologic structure consists of a 14-kilometer long, NE-trending range that shows three main synclines at both extremes (Conceicao and Caue) and middle (Minas do Meio) sections. The synclines branch out to the west from the general structure, and have created appropriate conditions to hold massive concentrations of the iron mineralization.

High-grade ores of Hematite and Itabirite, in continuous occurrence, are extracted along the structure, from the Conceicao mine at the southwest end to the Caue mine in the NE side of the range. The ore reserves at the Caue have been depleted. The Minas do Meio mine consists of numerous deposits located along the geologic structure, such as the Corpo D, Periquito, Dois Corregos, Onca, and Chacrinha.

The main iron ore types in the Iron Quadrangle are:

Hematite: Hematite represents the high-grade ore type within the iron deposit. The iron content varies from 65 to 67 percent. It is either massive or foliated in nature. The hematite is classified according to its physical and chemical characteristics as Compact Hematite, Friable Hematite, and Goethitic / Argilitic Hematite. Its origin is related to hydrothermal or metasomatic processes.

Itabirite: Itabirite is a term widely used in Brazil to denote a metamorphosed iron formation composed of iron oxides (hematite, magnetite, and martite), abundant quartz, very rarely mica, and other accessory minerals. It may be foliated or compact. The un-enriched (poor) itabirites from the Quadrilatero Ferrffero tend to have little magnetite, and composed principally of quartz-hematite, quartz-hematite-carbonate and hematite-carbonate. Itabirite represents the majority of reserves and resources of the Iron Quadrangle deposits. According to Vale, it was originated by silica leaching and residual iron-oxide enrichment process during post-metamorphic weathering cycles. The iron content averages about 45 percent, and occasionally it may reach up to 60 percent. The Itabirite ore is classified according to its physical and chemical characteristics as Compact Itabirite, Friable Itabirite, Goethitic / Argilitic Itabirite or Ochre.

Canga: Canga ore consists of unconsolidated talus material formed by the weathering of the iron formation. The iron content ranges significantly, with generally high concentration of phosphorous and alumina.

Rolados: A second detrital mineralization type. Consists of a ferruginous or lateritic matrix with fragments and blocks of different materials such as hematite, itabirite, quartz; high Fe grade, with high contaminant levels, such as P and Al203.s.

The beneficiation process for the run of mine consists of standard crushing, classification and concentration steps, producing sinter feed, lump ore and pellet feed.