The objective of this work is the study the crystal structure and elemental content of braunite-hematite and braunite-psilomelane oxide manganese ores y means of X-ray diffractometry (XRD), Energy Dispersion X-ray (EDX) analysis, and X-Ray fluorescent (XRF) analysis. It was found that heat treatments at 600, 800, and 1000 °C promote the phase transitions of the manganese ores to the formation of thermostable phases hausmannite and bixbyite without change in the metallic composition. The homogeneity of the structure increases with increasing temperature, which is expressed in the decreasing of the Mn content in the EDX spectra after sintering above 800 °C as well as in a decrease of the phase number to only two phases: bixbyite and quartz. Remarkably, the hausmannite phase is obtained in the fraction of 61% after sintering the braunite-hematite ore sample at 1000 °C for 4 h. Since hausmannite is widely used to produce building materials, electrodes, catalysts, and other materials, these results are promising for developing technologies for obtaining new products based on phases of manganese minerals at high temperatures.

The expansion of copper mining on the hyper-arid pacific slope of southern Peru has precipitated growing concern for scarce water resources in the region. Located in the headwaters of the Torata river, in the department of Moquegua, the Cuajone mine, owned by Southern Copper, provides a unique opportunity, in a little-studied region, to examine the relative impact of the landscape-scale mining on water resources in the region. Principal component analysis and cluster analysis of the water chemistry data from 16 sites, collected over three seasons during 2017 and 2018, show distinct statistical groupings indicating that, above the settlement of Torata, water geochemistry is a function of chemical weathering processes acting upon underlying geological units, and confirming that the Cuajone mine does not significantly affect water quality in the Torata river. Impact mitigation strategies that firstly divert channel flow around the mine and secondly divert mine waste to the Toquepala river and tailings dam at Quebrada Honda, below the Toquepala mine, in the department of Tacna, secure water quality in the Torata river for the foreseeable future. In the greater Moquegua river catchment, our results further suggest that water quality has been more significantly impacted by urban effluents and agricultural runoff than the Cuajone mine. The increase in total dissolved solids in the waters of the lower catchment reflects the cumulative addition of dissolved ions through chemical weathering of the underlying geological units, supplemented by rapid recharge of surface waters contaminated by residues associated with agricultural and urban runoff through the porous alluvial aquifer. Concentrations in some of the major ions exceeded internationally recommended maxima for agricultural use, especially in the coastal region. Occasionally, arsenic and manganese contamination also reached unsafe levels for domestic consumption. In the lower catchment, below the Cuajone mine, data and multivariate analyses point to urban effluents and agricultural run-off rather than weathering of exposed rock units, natural or otherwise, as the main cause of contamination.