Alena Zdravković

This study analyzes mineralogical composition and properties of two samples sourced from Dučevac, Serbia, which are traditionally used in hair treatment. This investigation provides the first systematic, multidisciplinary characterization of the specified material, comparing the samples with respect to their mineralogical phases, chemistry, and physicochemical properties. Notably, sample 1.1 is primarily calcite, with a smaller amount of clay minerals (illite, kaolinite, and smectite). In contrast, sample 1.2 showcases a blend of illite and quartz, with small amounts of other clay minerals (smectite, kaolinite, chlorite) and plagioclase. Sample 1.1 has higher amounts of CaO (9.83 wt.%) and Na2O (2.97 wt.%) than sample 1.2; in return, sample 1.2 has higher amounts of Fe2O3 (4.25 wt.%) and MgO (4.61 wt.%). In terms of pH, both samples are moderately acidic, with CEC values ranging from 8 to 9 meq/100g, and SSA measurements between 66 and 75 m²/100g. The color also reflects distinct variations, with sample 1.1 registering at 583 nm and sample 1.2 at 573 nm. All analytical values align with reference peloids found in literature, enhancing our understanding of the samples' characteristics and origins. This highlights the material's geological significance and the importance of preserving traditional practices as part of the region's geoheritage.

“Miloschite”, a chromium-containing halloysite with intense blue hues, was first discovered in 1835 in Rudnjak, Serbia. Some of the collected “miloschite” samples remained in Serbia and are kept in the University Collection of Minerals and Rocks (Faculty of Mining and Geology, University of Belgrade) and in the Natural History Museum in Belgrade. During the 19th and 20th centuries, numerous studies examined this mineral. From the original samples collected at the type locality—initially described as “miloschite” and later confirmed to be varieties of halloysite enriched in chromium—subsequent interpretations of the authors on similar material from other localities worldwide led to a misinterpretation of “miloschite” as chromium-bearing kaolinite. This reinterpretation now requires revision. This investigation was carried out on an original sample employing techniques such as powder X-ray diffraction, thermal and various spectroscopic methods, along with assessments of cation exchange capacity, specific surface area, and color determination. Analyses reveal that “miloschite” primarily consists of chromium-bearing halloysite, where chromium is evenly distributed on the microscale and fills octahedral sites within the clay lattice. This research aims to reaffirm the status of “miloschite” as a significant geoheritage material from Serbia and to preserve its nomenclatural integrity as the chromium variety of halloysite.

Constanta port operations involving the handling of bulk minerals often lead to material losses, resulting in mineral waste, containing a mixture of iron ore, bauxite, and coal, amongst others. In order to recover these minerals, a processing plant was built, which successfully separates most of this waste into its constituents. However, a byproduct obtained from this process is a sludge containing fine particles below 0.5 mm, which are deposited in a reservoir that represents definitive tailings. Since this is a “rich” tailing material, which is difficult to be extracted by using conventional methods due to its small size, the selective flocculation procedure was tested as an alternative method. This paper presents the results obtained for standard methods of selective flocculation tests using polyacrylamide A 100 at a pH value of 10.5. SEM-EDS and XRD analyses were performed, and the chemical composition of the sample components was given. According to preliminary tests, using the selective flocculation procedure, the expected results were obtained in terms of separating the overflow between the content of impurities (with a reduced share of Fe in relation to the input) and sediment with an increased content of Fe (with a reduced share of impurities in relation to the entrance).

The dominant sulfide minerals of the Pb-Zn deposit Sastavci are arsenopyrite, galena, and sphalerite. Oxidation of arsenopyrite can lead to the release of arsenic, a highly toxic environmental element. Oxidation products of arsenopyrite and other sulfides, present in the ores themselves as well as on the surfaces of samples, were analyzed by the OL microscopy in reflected light, SEM-EDS, and XRPD methods. It was established that scorodite and Fe sulfo-arsenates are the main alteration products of arsenopyrite. The Znand Mn-sulfates form crusts and aggregates on the surfaces of some samples. The conclusion is that the main concentrations of released As are found in scorodite, a relatively stable mineral in the surface conditions, and to a lesser extent in arsenolite.