Two new mineral species, vorontsovite, ideally (Hg₅Cu)TlAs₄S₁₂, and ferrovorontsovite, ideally (Fe₅Cu)TlAs₄S₁₂, the Tl- and Tl–Fe-analogues of galkhaite, respectively, have been discovered at the Vorontsovskoe gold deposit, Northern Urals, Russia. They occur as anhedral grains up to 0.5 mm (vorontsovite) and 0.2 mm (ferrovorontsovite) embedded in a calcite-dolomite matrix. The chemical composition of vorontsovite (wt %) is: Hg 35.70, Fe 5.36, Zn 1.26, Cu 3.42, Ag 0.64, Tl 11.53, Cs 0.35, Pb 0.04, As 15.98, Sb 2.35, Te 0.41, S 22.70, Se 0.02, total 99.76. The empirical formula, calculated on the basis of 23 atoms pfu, is: [(Hg_3.02Fe_1.63Zn_0.33)_Σ4.98(Cu_0.91Ag_0.10)_Σ1.01](Tl_0.96Cs_0.04)_Σ1.00(As_3.62Sb_0.33Te_0.05)_Σ4.00S_12.01. The composition of ferrovorontsovite (wt %) is: Hg 25.13, Fe 9.89, Zn 1.16, Cu 3.95, Ag 0.45, Tl 12.93, Cs 0.44, Pb 0.04, As 17.83, Sb 2.15, Te 0.40, S 24.91, total 99.28. The empirical formula, calculated on the basis of 23 atoms pfu, is: [(Fe_2.74Hg_1.94Zn_0.27)_Σ4.95(Cu_0.96Ag_0.06)_Σ1.02](Tl_0.98Cs_0.05)_Σ1.03(As_3.68Sb_0.27Te_0.05)_Σ4.00S_12.00. Both minerals are cubic, space group I-43m, with a = 10.2956(6) Å, V = 1091.3(1) ų, Z = 2 (vorontsovite); and a = 10.2390(7) Å, V = 1073.43(22) ų, Z = 2 (ferrovorontsovite). The crystal structures of both minerals were refined to R = 0.0376 (vorontsovite) and R = 0.0576 (ferrovorontsovite). Vorontsovite and ferrovorontsovite have been approved by the IMA-CNMNC under the numbers 2016-076 and 2017-007, respectively. The first one is named after the type locality, but also honors the mining engineer Vladimir Vasilyevich Vorontsov. The second is named for its chemical composition, as the Fe-analogue of the first. Both species are isostructural with galkhaite, being its Tl- and Tl–Fe analogues, respectively, and forming altogether the galkhaite group.

Tsygankoite, ideally Mn₈Tl₈Hg₂(Sb₂₁Pb₂Tl)_Σ24S₄₈, is a new sulfosalt discovered at the Vorontsovskoe gold deposit, Northern Urals, Russia. It occurs as lath-like elongated crystals up to 0.2 mm embedded in calcite–dolomite–clinochlore matrix. The associated minerals also include aktashite, alabandite, arsenopyrite, barite, cinnabar, fluorapatite, orpiment, pyrite, realgar, routhierite, sphalerite, tilasite, and titanite. The new mineral is non-fluorescent, black, and opaque with a metallic lustre and black streak. It is brittle with an uneven fracture and no obvious parting and cleavage. Its Vickers hardness (VHN₁₀) is 144 kg/mm² (range 131–167 kg/mm²) and its calculated density is 5.450 g cm. In reflected light, tsygankoite is white; between crossed polars it is dark grey to black. It is strongly anisotropic: rotation tints vary from light grey to dark grey to black. Pleochroism and internal reflections are not observed. The chemical composition of tsygankoite (wt %, electron-microprobe data) is: Mn 6.29, Hg 5.42, Tl 26.05, Pb 5.84, As 3.39, Sb 30.89, S 21.87, total 99.75. The empirical formula, calculated on the basis of 90 atoms pfu, is: Mn_8.06Tl_8.00Hg_1.90(Sb_17.87As_3.19Pb_1.99Tl_0.97)_Σ24.02S_48.03. Tsygankoite is monoclinic, space group C2/m, a = 21.362(4) Å, b = 3.8579(10) Å, c = 27.135(4) Å, β = 106.944(14)°, V = 2139.19(17) ų and Z = 1. The five strongest diffraction peaks from X-ray powder pattern (listed as (d,Å(I)(hkl)) are: 3.587(100)(112), 3.353(70)(−114), 3.204(88)(405), 2.841(72)(−513), and 2.786(99)(−514). The crystal structure of tsygankoite was refined from single-crystal X-ray diffraction data to R = 0.0607 and consists of an alternation of two thick layer-like arrays, one based on PbS-archetype and the second on SnS-archetype. Tsygankoite has been approved by the IMA-CNMNC under the number 2017-088. It is named for Mikhail V. Tsyganko, a mineral collector from Severouralsk, Northern Urals, Russia, who collected the samples where the new mineral was discovered.

Cesiokenopyrochlore is a new mineral belonging to the pyrochlore group. It was discovered in a specimen of granitic pegmatite collected at Tetezantsio, Betafo region, Madagascar. The mineral forms rough equant crystals up to 0.05 mm in size intergrown with béhierite and rynersonite. Cesiokenopyrochlore is light-brown, translucent, with resinous luster. D_calc. = 5.984 g/cm³. In reflected light it is light gray, isotropic, with strong light-brown internal reflections. The crystal structure was refined to R₁ = 0.0212. The mineral is cubic, ⁠, a = 10.444(1) Å, V = 1139.5(2) ų_, and Z = 8. The strongest lines of the powder X-ray diffraction pattern [d, Å, (I, %) (hkl)] are: 6.03 (37) (111), 3.70 (9) (220), 3.15 (100) (311), 3.02 (36) (222), 2.012 (17) (511, 333), 1.848 (19) (440), 1.576 (11) (622). The chemical composition is (wt.%; electron microprobe): Cs₂O 22.66, Na₂O 1.74, CaO 0.64, Nb₂O₅ 20.87, Ta₂O₅ 21.27, WO₃ 30.67, H₂O (calc) 0.12, total 97.97. The empirical formula of the holotype specimen calculated on the basis of (Nb+Ta+W) = 2 apfu and (O+OH) = 6 apfu and written according to the pyrochlore-supergroup nomenclature is Na_0.29Ca_0.06(Nb_0.81W_0.69Ta_0.50)_Σ2[O_5.93(OH)_0.07]_Σ6Cs_0.83. The simplified formula of the holotype specimen is □₂(Nb,W,Ta)_Σ2O₆Cs. Cesiokenopyrochlore is the first natural niobate to adopt the inverse pyrochlore structure.

The new mineral patynite was discovered at the massif of Patyn Mt. (Patynskiy massif), Tashtagolskiy District, Kemerovo (Kemerovskaya) Oblast’, Southern Siberia, Russia. Patynite forms lamellae up to 1 × 0.5 cm and is closely intergrown with charoite, tokkoite, diopside, and graphite. Other associated minerals include monticellite, wollastonite, pectolite, calcite, and orthoclase. Patynite is colorless in individual lamellae to white and white-brownish in aggregates. It has vitreous to silky luster, white streaks, brittle tenacity, and stepped fractures. Its density measured by flotation in Clerici solution is 2.70(2) g/cm³; density calculated from the empirical formula is 2.793 g/cm³. The Mohs’ hardness is 6. Optically, patynite is biaxial (−) with α = 1.568(2), β = 1.580(2), and γ = 1.582(2) (589 nm). The 2V (measured) = 40(10)° and 2V (calculated) = 44.1°. The Raman and IR spectra shows the absence in the mineral of H₂O, OH⁻, and CO₃²⁻ groups and B–O bonds. The chemical composition is (electron microprobe, wt.%): Na₂O 3.68, K₂O 5.62, CaO 26.82, SiO₂ 64.27, total 100.39. The empirical formula based on 23 O apfu is Na_1.00K_1.00Ca_4.02Si_8.99O₂₃. Patynite is triclinic, space group P1. The unit-cell parameters are: a = 7.27430(10), b = 10.5516(2), c = 13.9851(3) Å, α = 104.203(2)°, β = 104.302(2)°, γ = 92.0280(10)°, V = 1003.07(3) ų, Z = 2. The crystal structure was solved by direct methods and refined to R₁ = 0.032. Patynite is an inosilicate with a new type of sextuple branched tubular chain [(Si₉O₂₃)¹⁰⁻]_∞ with an internal channel and [(Si₁₈O₄₆)²⁰⁻] as the repeat unit. The strongest lines of the powder X-ray diffraction pattern [d_obs, Å (I, %) (hkl)] are: 3.454 (100) (2-1-1), 3.262 (66) (2-1-2), 3.103 (64) (02-4), 2.801 (21), 1.820 (28) (40-2). Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia with the registration number 5369/1.

Two new isostructural minerals udinaite and arsenudinaite with the end-member formulae NaMg₄(VO₄)₃ and NaMg₄(AsO₄)₃, respectively, are found in the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. They are associated with one another and anhydrite, diopside, hematite, schäferite, berzeliite, svabite, calciojohillerite, tilasite, reznitskyite, ludwigite, rhabdoborite-group borates, forsterite, magnesioferrite, fluorapatite, pliniusite, and powellite. Both minerals occur as equant tetragonal prismatic–dipyramidal crystals up to 0.15 mm, aggregates up to 1 cm and interrupted crusts up to 2 × 2 cm². Udinaite and arsenudinaite, visually indistinguishable from one another, are transparent, beige or brownish-yellowish, with vitreous lustre. Both minerals are optically uniaxial (–); ω = 1.785/1.777 and ε = 1.830/1.820, D_calc. = 3.613/3.816 g·cm⁻³ (udinaite/arsenudinaite). The empirical formulae are: udinaite: (Na_0.55Ca_0.16)_Σ0.71(Mg_4.04Mn_0.02Fe_0.01)_Σ4.07(V_1.63As_1.05P_0.28Si_0.03S_0.01)_Σ3.00O₁₂; arsenudinaite: (Na_0.57Ca_0.13)_Σ0.70(Mg_4.01Mn_0.01Fe_0.01)_Σ4.03(As_2.07V_0.84P_0.10Si_0.01S_0.01)_Σ3.03O₁₂. Both minerals are tetragonal, I-42d, Z = 4, a = 6.8011(2)/6.8022(1), c = 19.1839(12)/19.1843(6) Å, and V = 887.35(7)/887.66(4) ų, R₁ = 0.0287/0.0119 (udinaite/arsenudinaite). Their crystal structure consists of the helical chains of edge-sharing MgO₆ octahedra and isolated TO₄ tetrahedra, forming a heteropolyhedral pseudo-framework with Na cations located in cavities. Both minerals are isostructural to jeffbenite. Udinaite and arsenudinaite form an isomorphous series in which the contents of T constituents vary within (in apfu): V_1.6–0.1As_2.8–1.0P_0.4–0.0.

A new mineral, hanauerite, ideally AgHgSI, was found in the oxidation zone of Ag- and Hg-bearing ores at two old, abandoned mines in Rhineland-Palatinate, Germany. In a holotype specimen originating from the Schöne Aussicht Mine, Dernbach, Westerwald, it is associated with plumbogummite–hinsdalite series of minerals and goethite. In cotype from the Friedrichssegen Mine, Bad Ems, it is associated with perroudite, goethite, and quartz. At both localities, hanauerite occurs as a prismatic crystal up to 0.15 mm long and up to 0.02 mm thick. The mineral is yellow, transparent, with an adamantine lustre. It is brittle, and cleavage was not observed. The calculated density values are 6.671 and 6.575 g cm⁻³ for holotype and cotype, respectively. The empirical formulae calculated (from electron microprobe data) based on the sum of all atoms = 4 apfu are Ag_0.95Hg_1.00S_1.01(I_0.83Br_0.19Cl_0.03)_Σ1.05 for holotype and Ag_0.97Hg_0.97S_1.05(I_0.76Br_0.25)_Σ1.01 for cotype. Hanauerite is orthorhombic, space group Pmma; the unit cell parameters (from single-crystal X-ray diffraction data; holotype/cotype) are: a = 9.932(2)/9.9256(8), b = 4.6219(19)/4.6209(2), c = 9.891(4)/9.9006(4) Å, V = 454.0(3)/454.19(5) ų, and Z = 4. The crystal structure was studied on single crystals extracted from both holotype and cotype specimens; R1 = 0.0416 (holotype) and =0.0544 (cotype). In hanauerite, Hg²⁺ cations centre strongly distorted octahedra with two short Hg–S bonds (Hg and S atoms build “crankshaft-type” chains) and four strongly elongated Hg–I bonds. The Hg-centred octahedra are connected via common edges and faces to form corrugated layers; Ag⁺ cations are located between these layers. Hanauerite is named in honour of the German mineral collector Dr. Alfred Hanauer (1912–1988). The common crystal chemical features of mercury sulphohalide minerals are discussed.