Mitrofanovite, Pt₃Te₄, is a new telluride discovered in low-sulfide disseminated ore in the East Chuarvy deposit, Fedorovo–Pana intrusion, Kola Peninsula, Russia. It forms anhedral grains (up to ~20 μm × 50 μm) commonly in intergrowths with moncheite in aggregates with lukkulaisvaaraite, kotulskite, vysotskite, braggite, keithconnite, rustenburgite and Pt–Fe alloys hosted by a chalcopyrite–pentlandite–pyrrhotite matrix. Associated silicates are: orthopyroxene, augite, olivine, amphiboles and plagioclase. Mitrofanovite is brittle; it has a metallic lustre and a grey streak. Mitrofanovite has a good cleavage, along {001}. In plane-polarised light, mitrofanovite is bright white with medium to strong bireflectance, slight pleochroism, and strong anisotropy on non-basal sections with greyish brown rotation tints; it exhibits no internal reflections. Reflectance values for the synthetic analogue of mitrofanovite in air (R_o,R_e’in %) are: 58.4, 54.6 at 470 nm; 62.7, 58.0 at 546 nm; 63.4, 59.1 at 589 nm; and 63.6, 59.5 at 650 nm. Fifteen electron-microprobe analyses of mitrofanovite gave an average composition: Pt 52.08, Pd 0.19, Te 47.08 and Bi 0.91, total 100.27 wt.%, corresponding to the formula (Pt_2.91Pd_0.02)_Σ2.93(Te_4.02Bi_0.05)_Σ4.07based on 7 atoms; the average of eleven analyses on synthetic analogue is: Pt 52.57 and Te 47.45, total 100.02 wt.%, corresponding to Pt_2.94Te_4.06. The density, calculated on the basis of the formula, is 11.18 g/cm³. The mineral is trigonal, space groupR $\overline 3 $ m, witha= 3.9874(1),c= 35.361(1) Å,V= 486.91(2) ųandZ= 3. The crystal structure was solved and refined from the powder X-ray-diffraction data of synthetic Pt₃Te₄. Mitrofanovite is structurally and chemically related to moncheite (PtTe₂). The strongest lines in the powder X-ray diffraction pattern of synthetic mitrofanovite [din Å (I) (hkl)] are: 11.790(23)(003), 5.891(100)(006), 2.851(26)(107), 2.137(16)(1013), 2.039(18)(0114), 1.574(24)(0120), 1.3098(21)(0027). The structural identity of natural mitrofanovite with synthetic Pt₃Te₄was confirmed by electron backscatter diffraction measurements on the natural sample. The mineral name is chosen to honour Felix P. Mitrofanov, a Russian geologist who was among the first to discover platinum-group element mineralisation in the Fedorova–Pana complex.

Maletoyvayamite, Au₃Se₄Te₆, is a new mineral discovered in a heavy-mineral concentrate from the Gaching occurrence of the Maletoyvayam deposit, Kamchatka, Russia (60°19′51.87″N, 164°46′25.65″E). It forms anhedral grains (10 to 50 μm in size) and is found in intergrowths with native gold (Au–Ag), Au tellurides (calaverite), unnamed phases (AuSe, Au₂TeSe and Au oxide), native tellurium, sulfosalts (tennantite, tetrahedrite, goldfieldite and watanabeite) and supergene tripuhyite. Maletoyvayamite has a good cleavage on {010} and {001}. In plane-polarised light, maletoyvayamite is grey, has strong bireflectance (grey to bluish grey), and strong anisotropy; it exhibits no internal reflections. Reflectance values for maletoyvayamite in air (R_min,R_maxin %) are: 38.9, 39.1 at 470 nm; 39.3, 39.5 at 546 nm; 39.3, 39.6 at 589 nm; and 39.4, 39.7 at 650 nm. Sixteen electron-microprobe analyses of maletoyvayamite gave an average composition: Au 34.46, Se 16.76, Te 47.23 and S 0.84, total 99.29 wt.%, corresponding to the formula Au_2.90(Se_3.52S_0.44)_Σ3.96Te_6.14based on 13 atoms; the average of eleven analyses on synthetic analogue is: Au 34.20, Se 19.68 and Te 45.42, total 99.30 wt.%, corresponding to Au_2.90Se_4.16Te_5.94. The calculated density is 7.98 g/cm³. The mineral is triclinic, space groupP1, witha= 8.901(2),b= 9.0451(14),c= 9.265(4) Å, α = 97.66(3), β = 106.70(2), γ = 101.399(14)°,V= 685.9(4) ųandZ= 2. The crystal structure of maletoyvayamite represents a unique structure type resembling a molecular structure. There are cube-like [Au₆Se₈Te₁₂] clusters linkedviavan der Waals interactions. The structural identity of maletoyvayamite with the synthetic Au₃Se₄Te₆was confirmed by powder X-ray diffraction and Raman spectroscopy.

Gachingite, Au(Te_1–xSe_x), 0.2 ≈ x ≤ 0.5, is a new mineral discovered in the Gaching ore occurrence of the Maletoyvayam epithermal deposit, Kamchatka, Russia. Gachingite forms individual droplet-like grains of sizes from 2 to 10 μm included in native gold (Au–Ag), associated with calaverite, maletoyvayamite, watanabeite and Au–Sb oxides. The aggregates do not exceed 100 μm in diameter. In plane-polarised light, gachingite is grey with a bluish tint, has bireflectance (bluish-grey to deep grey), and strong anisotropy with rotation tints blue to dark blue to brown. Reflectance values for gachingite in air (R_min, R_max in %) are: 39.9, 40.3 at 470 nm; 41.6, 43.3 at 546 nm; 42.0, 43.7 at 589 nm; and 43.0, 44.0 at 650 nm. Eighteen electron-microprobe analyses of gachingite gave an average composition: Au 62.40, Ag 0.57, Se 9.78, Te 27.33 and S 0.01, total 100.09 wt.%, corresponding to the formula (Au_0.96Ag_0.02)_Σ0.98(Te_0.65Se_0.37)_Σ1.02 based on 2 apfu, the simplified formula is Au(Te_0.65Se_0.35); the average analyses of its synthetic analogue is Au 65.7, Se 13.1 and Te 21.1, total 99.9 wt.%, corresponding to Au_1.00(Te_0.50Se_0.50). The calculated density is 10.47 g/cm³. The mineral is orthorhombic, space group Cmce (#64) with a = 7.5379 Å, b = 5.7415 Å, c = 8.8985 Å, V = 385.12 ų and Z = 8. The crystal structure was solved and refined from the single-crystal X-ray-diffraction data of synthetic Au_1.00(Te_0.50Se_0.50). The crystal structure of gachingite represents a unique structure type, containing linear [Au–Au–Au] chains running along the b-axis indicating strong metallic interaction in one direction. The structural identity of gachingite and its synthetic analogue Au_1.00(Te_0.50Se_0.50) was confirmed by electron back-scatter diffraction and Raman spectroscopy. The formation of gachingite requires an abundant source of Au and Se and a high oxidising environment. Gachingite is related to the gold-bearing productive stage of ore mineralisation, which is stable at 250°C in log $f_{{\rm S}{\rm e}_ 2}$ range of −12.4 and −5.7. The mineral is named after its type locality.

The layered mineral tilkerodeite (Pd ₂ HgSe ₃ ), the palladium analogue of jacutingaite (Pt ₂ HgSe ₃ ), is a promising quantum spin hall insulator for low-power nanospintronics. In this context, a fast and reliable assessment of its structure is key for exploring fundamental properties and architecture of new Pd ₂ HgSe ₃ -based devices. Here, we investigate the first-order Raman spectrum in high-quality, single-crystal bulk tilkerodeite, and analyze the wavenumber relation to its isostructural jacutingaite analogue. By using polarized Raman spectroscopy, symmetry analysis, and first-principles calculations, we assigned all the Raman-active phonons in tilkerodeite, unveiling their wavenumbers, atomic displacement patterns, and symmetries. Our calculations used several exchange–correlation functionals within the density functional perturbation theory framework, reproducing both structure and Raman-active phonon wavenumbers in excellent agreement with experiments. Also, it was found that the influence of the spin–orbit coupling can be neglected in the study of these properties. Finally, we compared the wavenumber and atomic displacement patterns of corresponding Raman-active modes in tilkerodeite and jacutingaite, and found that the effect of the Pd and Pt masses can be neglected on reasoning their wavenumber differences. From this analysis, tilkerodeite is found to be mechanically weaker than jacutingaite against the atomic displacement patterns of these modes. Our findings advance the understanding of the structural properties of a recently discovered layered topological insulator, fundamental to further exploring its electronic, optical, thermal, and mechanical properties, and for device fabrication.

Panskyite, Pd9Ag2Pb2S4, is a new mineral (IMA2020–039) discovered in the platinum-group element mineralisation of the Southern Kievey ore occurrence of the Fedorova–Pana layered intrusion, Kola Peninsula, Russia. It forms tiny anhedral grains (of 0.5 to 10 μm in size) in the interstices of rock-forming silicates, often forming tiny inclusions in base-metal sulfides (millerite, chalcopyrite, bornite and chalcocite) and complex intergrowths with other platinum group minerals (zvyagintsevite, laflammeite, vysotskite, thalhammerite, unnamed phase Pd9Ag2(Tl,Pb)2S4 and others). In plane-polarised light, panskyite is creamy white with weak bireflectance, weak pleochroism and distinct anisotropy with brown to grey rotation tints; it exhibits no internal reflections. Reflectance values for panskyite in air (R 1, R 2 in %) are: 43.8, 44.1 at 470 nm; 44.4, 44.7 at 546 nm; 45.6, 45.8 at 589 nm; and 47.2, 47.2 at 650 nm. Twelve electron-microprobe analyses of panskyite gave an average composition: Pd 55.61, Ag 12.36, Pb 23.50, Fe 0.21, Ni 0.24 and S 7.17 total 99.09 wt.%, corresponding to the formula (Pd9.05Fe0.07Ni0.07)Σ9.19Ag1.98Pb1.96S3.87 based on 17 atoms; the average of nine analyses on the synthetic analogue is: Pd 57.02, Ag 14.17, Pb 21.81 and S 7.44, total 100.44 wt.%, corresponding to Pd9.07Ag2.22Pb1.78S3.93. The density, calculated on the basis of the empirical formula, is 9.81 g/cm3. The mineral is tetragonal, space group I4/mmm, with a = 7.973(3), c = 9.139(3) Å, V = 581.0(4) Å3 and Z = 2. The crystal structure was solved from the single-crystal and powder X-ray diffraction data of synthetic Pd9Ag2Pb2S4. Panskyite is isostructural with thalhammerite (Pd9Ag2Bi2S4). The mineral name is for the locality, the Pansky massif of the Fedorova–Pana layered intrusion in the Kola Peninsula, Russia.