Casa de Pedra mine is a hematite-rich iron deposit of an early proterozoic banded iron formation in Brazil’s Iron Ore Quadrangle (Quadrilátero Ferrífero), which is located in the central part of the state of Minas Gerais in the Southeastern region of Brazil.

The formations of economic interest in the mine area are hosted within the Minas Supergroup, Itabira Group, and Cauê Formation. The CdP is characterized by several occurrences of iron oxide, where the main hematitic bodies occur as lenses in the NW-SE direction. These lenses are present along a 50 km sinformal structure, having a normal flank in a North-South direction to the west and an inverted flank to the east of NW-SE, in the North portion, and which surrounds the Bação Metamorphic Complex in the South domain. The CdP mine is located on the western hinge of the Sinclinal Moeda.

The CdP mine area has undergone three deformational events which control deposit attributes between the Main and Western deposits within the CdP complex. These two deposits exhibit distinct differences in mineralogy and texture as a result of the individual structural domains. The Main body is composed of granular hematite and magnetite (itabirite) with porosity averaging 20% compared to the West body which is richer in specularite (specular hematite) and goethite with lower porosities averaging 17%.

Within the CdP mine, lithologies are defined from oldest to youngest as:

1. Chlorite Schists (Nova Lima Group - Rio das Velhas Supergroup).
2. Quartzites (Caraça Group - Moeda Formation).
3. Carbonous Filites (Grupo Caraça - Batatal Formation).
4. Iron formations and manganese rocks (Grupo Itabira - Cauê Formation).
5. Dolomites and dolomitic phyllites (Grupo Itabira - Gandarela Formation).
6. Sericita Xistos - (Grupo Piracicaba - Cercadinho Formation).
7. Mafic (basic) intrusives, primarily metagabbro.
8. Tertiary deposits (stratified clays).
9. Quaternary covers.

The CdP iron deposit is considered a Lake Superior-type banded iron formation (BIF or itabirite) deposit that has been enriched in iron and depleted in silica from a combination of supergene and hydrothermal processes. Iron ore is hosted in the banded iron Cauê Formation of the Itabira Group of the Paleoproterzoic Supergroup Minas with an approximate 2.52 Ga age. Enriched iron oxide is present as compact or friable hematite, semi-compact to compact itabirites, composed of millimeter to centimeter bands of hematite and/or magnetite with interlayered quartz.

Iron oxide enrichment through supergene processes is controlled along NW-SE thrust faults that bound the Main and West deposits. Hypogene alteration is evident through the presence of martite. The Cauê Formation consists of BIF, amphibolitic BIF, and dolomitic BIF with subordinate manganese and phyllite-rich zones. Stratigraphically above the Cauê Fm lies the Gandarela Formation consisting of carbonates and phyllitic itabirite.

The geometry of deformation within the two host deposits varies slightly due to the influence of regional structure. The West deposit exhibits foliation and bedding in a N-S direction until truncated by the main thrust fault separating the deposits. The more deformed Main deposit exhibits a NW-SE foliation roughly perpendicular to the highly deformed bedding.

Casa de Pedra is an open pit mine located in the city of Congonhas, in the state of Minas Gerais, approximately 80 km south of the city of Belo Horizonte and 360 km north of the city of Rio de Janeiro.

The Casa de Pedra mine is based on a mining concept that uses conventional drill, blast, load and haul techniques for all mining areas and rock types. 100% of rock will be blasted and loaded with excavators and loaders into off-road trucks, and hauled to final destinations, i.e., primary crusher, stockpiles or waste dumps. Specifically, primary mining will be undertaken by large hydraulic excavators (26-m3 bucket capacity) coupled with 240st off-road trucks. Front-end loaders of 25-m3 bucket capacity will also operate at the pit and stockpiles.

The materials will be mined in 13-m high benches which are considered an appropriate balance between productivity and selectivity.

The geometrical assumptions are listed below:

- Slope and bench geometric parameters: derived from the geotechnical recommendations.
- Roads and ramps width: 35 m.
- Maximum ramp gradient: 10%.

Grade control will be performed via drilling, sampling and assaying potential ore material within the pit boundaries.

The mine will operate 365 days, 24 hours in 3 shifts. The base case for the Project is an owner’s operation.

The iron ore is processed in treatment facilities, which have an installed capacity of 33 million tons of products per year (a sum of the central plant, mobile plants and Pires treatment facilities).

Casa de Pedra mine supplies all of iron ore needs, except pellets, and produces lump ore, sinter feed and pellet feed fines with high iron content.

Casa de Pedra’s treatment facilities have an installed annual run of mine capacity of approximately 40 million tons.