Peña Colorada is a complex polyphase iron ore deposit. The iron mineralization at Peña Colorada consists of banded to massive concentrations of magnetite within breccia zones and results from several magmatic, metamorphic and hydrothermal mineralization stages with associated skarns, dykes and late faults sectioning the entire deposit.

The Peña Colorada mineralized area contains several iron oxide-apatite (IOA) deposits around the arguably richest known iron resource in Mexico. The Lower Cretaceous volcano-sedimentary host rock sequence has been subjected to several episodes of hydrothermal alteration, each accompanied by a distinct episode of faulting and intrusion (calc-alkaline to tholeiitic). Faulting is partly associated with the reactivation of cryptic structural corridors in basement rocks. High-resolution 40Ar/39Ar and apatite fission track (AFT) dating of this deposit and the adjacent Arrayanes prospect reveal the following sequence of events that range from the latest Cretaceous to the earliest Eocene: (1) intrusion of a 67.6 ± 3.5 Ma magnetite-bearing diorite with associated skarn/skarnoid metamorphism that was coeval or predated N-S to NNW-SSE faulting; (2) approximately 63.26 Ma syenite-like potassic alteration with disseminated magnetite, predated by N-S to NNW-SSE faulting and postdated by WNW-ESE faulting; (3) intrusion of 62.0 ± 2.5 Ma diorite and 59.39 ± 0.21 Ma andesite dikes that predate the main mineralization event at 55.72 to 54.84 Ma of large semi-stratabound massive and disseminated bodies; (4) intrusion of a 53.3 ± 3.0 Ma magnetite-bearing gabbro and 53 ± 2 Ma pegmatoid magnetite + fluorapatite veins at the Arrayanes prospect, which overlap the WNW-ESE faulting; (5) 50.70 to 48.18 Ma polymictic magnetite breccia as the last stage of mineralization in the area, predated by E-W faulting; and (6) reactivation of WNW-ESE faults and later NE-SW faults. Therefore, the total age span of the Peña Colorada deposit ranges between approximately 19 and 23 million years. The closeness in age between intrusions and mineralization in the Arrayanes prospect, their confinement between the WNW-ESE and E-W structural domains, and mingling or mixing structures between gabbro and diorite with an associated magmatic magnetite enrichment support the idea of a close genetic link between such intrusives and IOA hydrothermal mineralization. All mineralization events at Peña Colorada are associated with pervasive potassic to propylitic alteration, whereas at Arrayanes they are associated with dominant sodic alteration instead. Alteration features are suggestive of relatively shallow and deep formation of these deposits, respectively. Event 3 thermally reset fluorapatite in fragments of pegmatoid magnetite + fluorapatite + diopside associations (dated at 59 ± 2 Ma, AFT) within the polymictic breccia, which were sampled from a deep orebody (still to be found) and that would be likely associated with event 1 or 2. Consequently, exploration endeavors at depth at Peña Colorada may be considered promising.

The Peña Colorada iron oxide-apatite (IOA) deposit is located in the northern part of the state of Colima, SW Mexico. The majority of magmatic-hydrothermal iron oxide deposits (or IOCG “clan” deposits) in SW Mexico span Late Cretaceous to Eocene ages (Camprubí, 2009, 2013, 2017; Camprubí and González-Partida, 2017). These are located less than approximately 200 km inland from the paleo-trench in the Pacific margin (Figure 1), not unlike similar deposits in the Andean coastal ranges (Camprubí, 2017; Camprubí and González-Partida, 2017). Their distribution follows that of Late Cretaceous to Eocene magmatism, although the regional tectonomagmatic regime and its evolution are poorly known. Likewise, no clear genetic association between magmatism and such iron deposits has been established.

Mineralogy of the deposits
Peña Colorada The mineralization model of the Peña Colorada deposit is established as a multi-stage, skarn-related, magmatic-hydrothermal iron oxide-apatite (IOA) deposit, and thus it is a part of the IOCG “clan” of ore deposits (Zürcher et al., 2001; Tritlla et al., 2003; Camprubí and Canet, 2009; Camprubí and González-Partida, 2017). This deposit and the neighboring La Fundición prospect are enveloped by widespread potassic alteration, particularly in the lower part of the deposit. Little sodic alteration, and conspicuous propylitic alteration occur in the upper part of the deposit. Potassic alteration is characterized by an assemblage of K-feldspar, ferroan chlorite (chamosite), apatite, magnetite, and accessory titanite, and can be found in other mineralized areas in the region, sometimes in close association with propylitic alteration laterally. Sodic alteration is characterized by the occurrence of actinolite or albite. Propylitic alteration consists of epidote, ferroan chlorite, calcite, analcime, zeolites, and chalcedony or quartz. The various mineralization events in the Peña Colorada deposit display strong textural and structural differences. The most notorious mineralization styles are apparently stratabound massive and disseminated ore bodies that are hosted by the volcano-sedimentary rocks of the Tepalcatepec Formation.

Located in the state of Colima, Peña Colorada is one of the largest iron ore operations in Mexico. The project is owned in equal parts by ArcelorMittal and Ternium.

Peña Colorada is a mining company that produces about 30 percent of the iron ore in Mexico. This project generates about 1,200 direct jobs and 3,000 indirect jobs, making a significant contribution to the local economy. Peña Colorada’s operations consist of an open pit mine located in Minatitlán and a pellet plant located in the port city of Manzanillo.

Most mining projects around the world typically follow the logic of “mining the next best ore.” Consequently, head grades tend to decline over the life of the mine. In the case of Peña Colorada, a decline in head grade combined with a decline in iron ore prices forced the operation to adapt to a new business environment and adopt new technologies to face these challenges. However, the first step along this process was to increase the confidence and reliability of the resource model. This task involved additional drillhole campaigns coupled with more detailed modeling techniques. Once the block model was completed, new optimization studies and production schedules were evaluated with new optimization tools that improved many aspects of the mine plan. The Peña Colorada block model has undergone 3 expansions to reflect additional information not available in the past. The model has expanded to the East and Southwest. The latest model expansion increased the total number of benches to 98 as a result of positive exploration results. Similarly, new geotechnical studies were prepared, which provided new guidelines for pit slope design, and new technology was implemented to monitor ground movement and slope stability. Two sectional block model views in Hexagon Mining’s MineSight 3D, along with the pit designs and geologic solids.

Similarly, Peña Colorada implemented a new fleet management system to monitor the operation and ensure plan execution and compliance, thus capturing in the field the value of the project as forecasted in the mine plan. However, there is always a variance between plan and reality. This has been significantly reduced with the adoption of best-in-class mine planning software and fleet management system. The implementation of these Hexagon Mining technologies narrowed the chasm between what is and what should be; and helped not only shape smart change but also unlock and realize project value.

Major processing facilities include a primary crusher, a dry cobbing plant, two autogenous mills, three horizontal and two vertical ball mills.

Peña Colorada operates an open pit mine as well as a concentrating facility and a two-line pelletizing facility. The beneficiation plant is located at the mine, whereas the pelletizing plant is located in Manzanillo. Major processing facilities include a primary crusher, a dry cobbing plant, two autogenous mills, three horizontal and two vertical ball mills and several stages of magnetic separation. The concentrate is sent as a pulp through a pipeline from the mineral processing plant to pelletizing facilities.

The concentrate is sent as a pulp through a 45 kilometers-long pipeline from the mine and mineral processing plant in Minatitlán to the pelletizing plant in Manzanillo. Consorcio Peña Colorada has an operational tailings dam in Arrayanal, Colima, and a tailings dam in the process of closure located in Guásimas, Colima, with limited use. In July 2019, a new paste plant was started up near the Arrayanal dam to increase the efficiency and speed of water recov ........