In the northern Fennoscandian Shield, a vanadium mineralization occurs in the Paleoproterozoic Pechenga–Imandra-Varzuga (PIV) riftogenic structure. It is localized in sulfide ores hosted by sheared basic and ultrabasic metavolcanics in the Pyrrhotite Ravine and Bragino areas and was formed at the latest stages of the Lapland-Kola orogeny 1.90–1.86 Ga ago. An additional formation of vanadium minerals derived from contact metamorphism and metasomatism produced by the Devonian Khibiny alkaline massif in the Pyrrhotite Ravine area. Vanadium forms its own rare minerals (karelianite, coulsonite, kyzylkumite, goldmanite, mukhinite, etc.), as well as it can be an isomorphic admixture in rutile, ilmenite, crichtonite group, micas, chlorites, etc. Vanadium originated from two sources: (1) basic and ultrabasic volcanics initially enriched in vanadium and (2) metasomatizing fluids that circulated along shear zones. The crystallization of vanadium and vanadium-bearing minerals was accompanied by chromium and scandium mineralization. Vanadium mineralization in Paleoproterozoic formations throughout the world is briefly considered. The simultaneous development of vanadium, chromium and scandium mineralizations is a unique feature of the Kola sulfide ores. In other regions sulfide ores contain only two of these three mineralizations produced by one ore-forming process.

This paper presents petrography, EDS, LA-ICP-MS, and Raman spectroscopy data characterizing mineral associations and composition of apatite group minerals from anorthosites of the Kievey deposit, North PGE Reef, Fedorova-Pana Complex, Russia. The mineralized coarse-grained anorthosite belongs to the most common rock type of the main ore body and hosts irregular interstitial sulfide dissemination of 5–7 vol. %. Apatite in the anorthosite forms a) euhedral grains included in the marginal parts of cumulus plagioclase laths, and b) xenomorphic grains associated with intercumulus minerals. The composition of apatite evolves along a narrow trend from fluorapatite to hydroxylapatite. The F content in apatite reaches 2.21 wt. %; the maximum Sr and REE concentration is 257 and 5623 ppm respectively, while the average ratio of La/YbN=11.78, Sr/Sr*=0.01, and Eu/Eu*=0.06. Compared to classic PGE reefs in layered intrusions such as Bushveld in South Africa and Stillwater in the United States, the mineralized anorthosite is distinguished by apatite with an unusual low chlorine concentration of only 0.46 wt. %. One of suggested reason of this difference is percolating nature of sulfide liquid which has not been enriched in PGE in situ.

This study analyzes the elemental and oxide compositions of three selected agricultural residues—Dried Pawpaw Leaves (DPL), Kolanut Pod (KNP), and Sweet Orange Peel (SOP)—for their potential as heterogeneous catalysts. Energy Dispersive X-ray (EDX) analysis identified calcium (25%) and potassium (29%) as the primary elements in DPL and KNP, with calcium oxide (CaO) and potassium oxide (K2O) as the dominant oxides. SOP had a similar composition but lacked vanadium. Calcined residues were analyzed at temperatures ranging from 500°C to 900°C using X-ray Fluorescence (XRF), revealing stable silicon dioxide (SiO2) content and temperature-dependent variations in CaO and K2O, indicating their catalytic potential for transesterification processes. Scanning Electron Microscopy (SEM) showed non-uniform, spongy microstructures, enhancing the surface area and catalytic efficiency. Fourier Transform Infrared Spectroscopy (FTIR) identified functional groups essential for catalytic activity, such as hydroxyls, methyl, and carboxyl. X-ray Diffraction (XRD) confirmed the presence of crystalline phases like calcium carbonate and calcium oxide, crucial for catalytic performance. Experimental biodiesel production using a mixture of the calcined residues (33.33% each of KNPA, SOPA, and DPLA) resulted in the highest biodiesel yield at 65.3%. Model summary statistics, including R² (0.9824) values and standard deviations (0.0026), validated the experimental design, indicating high precision and prediction accuracy. These results suggest that the selected agricultural residues, when calcined and mixed properly, can serve as effective heterogeneous catalysts, with significant implications for biodiesel production, supporting previous research on the importance of calcium in catalytic processes.