This paper poses a major question regarding the choice of space group for scapolite mineral group members. An artificial boundary is typically drawn between space groups I4/m and P4₂/n when solving the structures of scapolites within the marialite–meionite series. The authors debate if solving the crystal structure in lower symmetries is justified. The choice of space group here is attributed to Si-Al ordering of the framework, and it is shown that the interstitial framework cations and anions have an accompanying role in that decision. Some answers on the ranges and limits of distribution of space groups of scapolite members in the marialite–meionite series, and the manifestations of violation of the Lowenstein rule or the so-called aluminum avoidance rule are presented. Modern physical methods (SEM-EDS and SXDA) are employed in the study to properly analyze the solid solution series in detail. New crystal–chemical data are reported for scapolite samples from different localities. An analysis was made for the types of possible Al-O-Al bonds that can occur in the structures at different Al:Si ratios and their influence on Al-Si ordering. Finally, genetic considerations about Al-Si ordering in the framework construction during the mineral formation processes are proposed.

The current study presents the electron beam melting (EBM) efficiency of copper technogenic material with high impurity content (Se, Te, Pb, Bi, Sn, As, Sb, Zn, Ni, Ag, etc.) by means of thermodynamic analysis and experimental tests. On the basis of the calculated values of Gibbs free energy and the physical state of the impurity (liquid and gaseous), a thermodynamic assessment of the possible chemical interactions occurring in the Cu-Cu₂O-Me_x system in vacuum in the temperature range 1460–1800 K was made. The impact of the kinetic parameters (temperature and refining time) on the behaviour and the degree of removal of impurities was evaluated. Chemical and metallographic analysis of the obtained ingots is also discussed.

Samples of scapolite from the marble quarry from the Samurski Dol locality, situated nearby Chepelare, Central Rhodopes, Bulgaria have been subjected to chemical analyses and single crystal X-ray diffraction studies. The obtained values for the meionite component (Me) range between 70 and 75. The crystal structure of the studied sample has been solved in both I4/m and P42/n space groups, traditionally assigned to scapolite members. The paper provides new insight on the choice of correct space group for description of scapolites crystal structures, with a view of the preferred positions by silicon and aluminum ions and their framework ordering.

A flash smelting furnace operation is based on the exothermic reduction of copper concentrates in the combustion shaft, and these reactions occur at high temperatures (1250–1350 °C), where flame control is fundamental to optimizing copper reduction. Furthermore, inherent physicochemical reactions of the reduction process have been shown to emit spectral lines in the visible-near infrared spectrum (250–900 nm). Thus, an optoelectronic sensor prototype is proposed and developed for flame measurements of an industrial copper concentrate flash smelting furnace. The sensor system is composed of a high-temperature optical fiber probe, which functions as a waveguide to capture the emitted flame radiation and a visible-near infrared spectrometer. From the measured radiation, flame temperature and flame dynamics are analyzed. Flame temperature is estimated using the two-wavelength temperature estimation method, and flame dynamics are defined as variations in the total emissive power, which are studied in the time and frequency domain via the Fourier Transform method. These combustion dynamics are then used to create a flame instability index, which is used to characterize the flame combustion quality. The combination of this index and sensor platform provides a powerful tool to aid in proper flame control.

In the present research, we have applied a combination of Cold-CL petrography with two in-situ techniques (SEM-EDS and LA-ICP-MS) to study quartz-pyrite-sericite veins with some carbonates from the Elatsite porphyry Cu-Au deposit. Based on Cold-CL images, we found out that these veins are formed during two stages: quartz-pyrite with sericite and later quartz-carbonate with chlorite. Together with the quartz and carbonates small amount of arsenian pyrite, hematite, chalcopyrite, sphalerite, galena and apatite are precipitated. SEM-EDS and LA-ICP-MS allowed determining that the observed zoning of the pyrite from Q-Py stage is due to a variable Co and Ni content. Similarly, the zonal growth of calcite is due to variable Mn content. Pyrite and arsenian pyrite have different trace element composition. Arsenian pyrite has elevated Au, Ag, Cu, Pb, Sb and Tl contents compared to the pyrite. The combination of the three techniques was essential for resolving temporal relationships between the minerals within quartz-pyrite-carbonate veins and changes of the composition of the pyrite from the quartz-pyrite-sericite to the later quartz-carbonate stage.