The results of studying the isotopic, geochemical, and TEDS properties of various generations of pyrite and pyrrhotite from the Ugakhan deposit, Bodaibo district of Irkutsk region, are presented. Differences in the composition of impurities are established. Early pyrites (py-I and py-II) are characterized by the presence of Ni, Co, Cr, and Au admixtures, the electronic type of conductivity, and values of δ34S ~ +5.6‰; py-III is characterized by a decreased amount of Ni, Co, and Cr, and an increased amount of As, the hole type of conductivity, and δ34S from +8.6 to +9.1‰. Post-ore py-IV and py-IVQ are characterized by the smallest admixture concentrations, the electronic type of conductivity, and isotopically lighter sulfur (δ34S ≤ +3.8‰).

On the example of studying the EMF of pyrrhotite, pyrite, and arsenopyrite from gold deposits of the Yana-Kolyma orogenic belt and the Bodaybo synclinorium, using the local determination method for polished sections, it is shown that this parameter for pyrite and arsenopyrite is an important genetic sign of the their origin. Thermoelectric properties of pyrite and arsenopyrite can be used to estimate not only the temperature of their formation but also the temperature parameters of their metamorphism, as well as to characterize the generation of these minerals. The development of local methods for measuring EMF contributes to the possibility of using them for genetic constructions, especially in the study of gold sulfide-impregnated and lode-veinlet mineralization within structures of different-age orogenic belts.

Compositions of rare mineral phases containing precious metals (PMs) in samples from Natalka, Pavlik, Vetrenskoe, and Degdekan gold ore deposits (North-East of Russia) are studied by scintillation atomic emission spectrometry (SAES) and electron probe microanalysis (scanning electron microscopy and electron probe X-ray microanalysis, SEM–EPMA). The SAES method found dozens and hundreds of particles carrying gold, silver, and all platinum-group elements as native metals, intermetallides and solid solutions, arsenides, antimonites, sulfoarsenides, tellurides, selenides, etc. The variety of the elemental compositions of PM species (mineral phases) found by SAES significantly exceeds the list of minerals found previously by SEM–EPMA because of different natures of optical and X-ray spectra. The sizes of PM particles calculated by the SAES method and measured by SEM–EPMA are similar. The SAES data on the total concentrations of PMs satisfactorily agree with the results of inductively coupled plasma mass spectrometry.

Scintillation arc atomic-emission spectrometry (SAES) is used to study noble metals (NM), including Au, Ag, Pt, Pd, Ir, Os, Rh, and Ru, in black shales of the Sukhoi Log gold deposit (Irkutsk Region, Russia), with a focus on NM total contents in samples and on the compositions and sizes of NM-bearing particles. The estimated sizes of gold particles and their distribution are confirmed by results of scanning electron microscopy combined with energy dispersive X-ray microanalysis (SEM-EDX). The SAES results are in satisfactory agreement with earlier SEM-EDX data on NM species but reveal a much greater number and diversity of element associations.

The results of investigation of heavy fraction minerals from the Degdekan deposit hosted by the lower portion of stratified Mid Permian sediments are presented; the investigation was conducted via electron microscopy using a QEMSCAN hardware and software instrument equipped with a QUANTAX quantitative analysis system. The following mineral phases of platinoids have been detected for the first time: native osmium, rutheniridosmine, osmiridium, ruthenosmiridium, laurite, iridarsenite, and Ru, Os, and Ir arsenide.

Bortnikovite, a new mineral species that is an intermetallic compound of Pd, Cu, and Zn with the simplified formula Pd4Cu3Zn has been detected at the unique Konder placer deposit in the Ayan-Maya district, Khabarovsk krai. The primary source of this placer is a concentrically zoned alkaline ultramafic massif. The X-ray diffraction pattern is indexed on the assumption of a tetragonal unit cell: a = 6.00 ± 0.02 Å and c = 8.50 ± 0.03 Å, V = 306 ± 0.01 Å3, Z = 3, probable space group P4/mmm. The calculated density is 11.16 g/cm3; the mean microhardness VHN is 368 kg/mm2. In reflected light, the new mineral is white with a slight grayish beige tint; bireflectance, anisotropy, and internal reflections are not observed. The reflectance spectrum belongs to the concave group of the anomalous type. The measured values of reflectance are as follows: 56.9 (470 nm), 61.7 (546 nm), 63.4 (589 nm), and 65.4% (650 nm). The new mineral is intergrown with isoferroplatinum, titanite, perovskite, V-bearing magnetite, bornite, and chlorite. The origin of bortnikovite is related to the effect of alkaline fluid on ultramafic rocks. The new mineral is named in honor of Professor Nikolai Stefanovich Bortnikov, a prominent mineralogist and researcher of ore deposits and a corresponding member of the Russian Academy of Sciences. Bortnikovite is the first platinum group mineral that contains Zn as a major mineralforming element.