Mineralogical Study and Genetic Model of Efflorescent Salts and Crusts from Two Abandoned Tailings in the Taxco Mining District, Guerrero (Mexico)

• Published in: Minerals (Basel) 2020-10, Vol.10 (10), p.871
• Main Authors: Pi-Puig, Teresa, Solé, Jesús, Gómez Cruz, Adriana
• Format: Article
• Language: English
• Subjects: Abandoned mines; Aluminum; Analytical methods; Chemical analysis; Chemical reactions; Concretions; Contamination; Crusts; Dehydration; Dissolution; Dissolving; Drainage; Efflorescence; Electron microscopy; Gypsum; hydrated sulfates; Hydroxides; Inductively coupled plasma mass spectrometry; Infrared spectroscopy; Iron; Jarosite; Mass spectrometry; Mass spectroscopy; Mine tailings; Mine wastes; Mineralization; Mineralogy; Minerals; Mining; mining waste; Neutralization; Oxidation; Oxides; Pyrite; Rainy season; Rietveld method; Salts; Scanning electron microscopy; Short wave radiation; Silver; Silver mines; Spatial distribution; Spectrum analysis; Sulfates; Sulfides; Sulphates; SWIR; Tailings; Toxicity; Vegetation; Wave diffraction; Wet season; X rays; X-ray diffraction
• ISSN: 2075-163X; 2075-163X
• DOI: 10.3390/min10100871

The mineralogy of surface crusts and efflorescent salts of two old abandoned tailings (Xochula and Remedios) of the mining district of Taxco, Guerrero, was studied by short-wave infrared spectroscopy (SWIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The chemistry of the selected samples was studied with induced coupled plasma mass spectrometry (ICP–MS). Principal mineralogy is composed of hydrated sulfates of iron (di-trivalent), other less-soluble sulfates such as gypsum and jarosite, and oxides–hydroxides of iron, all of which are the result of the weathering of sulfides (mainly pyrite) accumulated in mining waste. Using quantitative X-ray diffraction (Rietveld method) and the spatial distribution of secondary minerals, two main zones (lateral and central) have been established in both tailings. The genetic model for their formation shows that the secondary iron minerals (sulfates, oxides, and hydroxides) in these deposits have been formed at least in three different stages, mainly by oxidation, dissolution, and precipitation processes in combination with dehydration and primary sulfides neutralization reactions. The chemical analyses of some salts confirm the presence of potentially toxic elements (PTE) in their structure and therefore indicate that the dissolution of the efflorescences in these deposits is a potential source of contamination during the wet season.