The mineralogy and weathering of thallium-rich waste dumps of Crven Dol locality, Allchar deposit

The Crven Dol area of the former Sb–As–Tl–Au Allchar mine (North Macedonia) contains large quantities of abandoned mine waste that is extremely rich in thallium (Tl) and arsenic (As). According to ĐORĐEVIĆ et al. (2021), these wastes often contain up to 142 g/kg of As and up to 18 g/kg of Tl, both of which are retained in primary sulfides and in newly formed secondary minerals resulting from the oxidative weathering of Tl-bearing
metal sulfides. In addition to well-known secondary Tl minerals, many poorly- or nanocrystalline phases lack appropriate chemical and structural characterization. Therefore, we are working extensively to characterize various specimens containing these two pollutants. As part of the current study, we mineralogically characterized two weathered hand specimens (Allchar 1 and 2) using secondary electron microscopy with energy dispersive X-ray
spectrometry (SEM-EDS), powder X-ray diffraction (PXRD), and Raman spectroscopy.