Dritsite, ideally Li₂Al₄(OH)₁₂Cl₂·3H₂O, is a new hydrotalcite supergroup mineral formed as a result of diagenesis in the halite−carnallite rock of the Verkhnekamskoe salt deposit, Perm Krai, Russia. Dritsite forms single lamellar or tabular hexagonal crystals up to 0.25 mm across. The mineral is transparent and colourless, with perfect cleavage on {001}. The chemical composition of dritsite (wt. %; by combination of electron microprobe and ICP−MS; H₂O calculated by structure refinement) is: Li₂O 6.6, Al₂O₃ 45.42, SiO₂ 0.11, Cl 14.33, SO₃ 0.21, H₂O_calc. 34.86, O = Cl − 3.24, total 98.29. The empirical formula based on Li + Al + Si = 6 apfu (atom per formula unit) is Li_1.99Al_4.00Si_0.01[(OH)_12.19Cl_1.82(SO₄)_0.01]_Σ14.02·2.60(H₂O). The Raman spectroscopic data indicate the presence of O–H bonding in the mineral, whereas CO₃^2– groups are absent. The crystal structure has been refined in the space group P6₃/mcm, a = 5.0960(3), c = 15.3578(13) Å, and V = 345.4(5) ų, to R₁ = 0.088 using single-crystal data. The strongest lines of the powder X-ray diffraction pattern (d, Å (I, %) (hkl)) are: 7.68 (100) (002), 4.422 (61) (010), 3.832 (99) (004, 012), 2.561 (30) (006), 2.283 (25) (113), and 1.445 (26) (032). Dritsite was found as 2H polytype, which is isotypic with synthetic material and shows strong similarity to chlormagalumite-2H. The mineral is named in honour of the Russian crystallographer and mineralogist Prof. Victor Anatol`evich Drits.

The crystal structure of a naturally occurring layered double hydroxide mineral—desautelsite from San Benito County, California, USA—was refined using single-crystal X-ray diffraction data in the space group R-3m, a = 3.1238(2) Å, c = 23.528(3) Å, V = 198.83(4) ų, and Z = 3/8. The Mg and Mn cations are disordered occurring in one M site with occupancy Mg_0.77Mn_0.23. According to the electron microprobe analysis supported by Raman spectroscopy, the empirical formula is Mg_6.20(Mn^III_1.78Al_0.01Fe^III_0.01)_Σ1.80(OH)₁₆(CO₃)_0.90·5.35H₂O that shows higher content of interlayer (H₂O) molecules in comparison to the ideal formula that also agrees with the structure refinement. The Raman spectroscopy of two samples indicated O–H vibrations (3650/3640 cm⁻¹, ~3500 sh cm⁻¹), symmetric C–O (1055/1057 cm⁻¹), Mg–O–Mg (533/533 cm⁻¹) and Mn–O–Mn (439/438 cm⁻¹) stretching vibrations and lattice vibrations (284/287 cm⁻¹). Summing up our data and that of the current literature, we show a correlation (R² = 0.91) between the averaged effective ionic radius (x) and a unit cell parameter (y) of hydrotalcite group minerals, $y=1.9871x+1.4455$. Desautelsite follows this correlation, being the species with one of the largest a unit cell parameters among the group. The correlation can be applied for control of cation intercalation during synthesis.

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, dioskouriite, CaCu₄Cl₆(OH)₄∙4H₂O, represented by two polytypes, monoclinic (2M) and orthorhombic (2O), which occur together, was found in moderately hot zones of two active fumaroles, Glavnaya Tenoritovaya and Arsenatnaya, at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Dioskouriite seems to be a product of the interactions involving high-temperature sublimate minerals, fumarolic gas and atmospheric water vapor at temperatures not higher than 150 °C. It is associated with avdoninite, belloite, chlorothionite, eriochalcite, sylvite, halite, carnallite, mitscherlichite, chrysothallite, sanguite, romanorlovite, feodosiyite, mellizinkalite, flinteite, kainite, gypsum, sellaite and earlier hematite, tenorite and chalcocyanite in Glavnaya Tenoritovaya and with avdoninite and earlier hematite, tenorite, fluorophlogopite, diopside, clinoenstatite, sanidine, halite, aphthitalite-group sulfates, anhydrite, pseudobrookite, powellite and baryte in Arsenatnaya. Dioskouriite forms tabular, lamellar or flattened prismatic, typically sword-like crystals up to 0.01 mm × 0.04 mm × 0.1 mm combined in groups or crusts up to 1 × 2 mm² in area. The mineral is transparent, bright green with vitreous luster. It is brittle; cleavage is distinct. The Mohs hardness is ca. 3. D_meas is 2.75(1) and D_calc is 2.765 for dioskouriite-2O and 2.820 g cm⁻³ for dioskouriite-2M. Dioskouriite-2O is optically biaxial (+), α = 1.695(4), β = 1.715(8), γ = 1.750(6) and 2V_meas. = 70(10)°. The Raman spectrum is reported. The chemical composition (wt%, electron microprobe data, H₂O calculated by total difference; dioskouriite-2O/dioskouriite-2M) is: K₂O 0.03/0.21; MgO 0.08/0.47; CaO 8.99/8.60; CuO 49.24/49.06; Cl 32.53/32.66; H₂O(calc.) 16.48/16.38; -O=Cl −7.35/−7.38; total 100/100. The empirical formulae based on 14 O + Cl apfu are: dioskouriite-2O: Ca_1.04(Cu_4.02Mg_0.01)_Σ4.03[Cl_5.96(OH)_3.90O_0.14]_Σ10∙4H₂O; dioskouriite-2M: (Ca_1.00K_0.03)_Σ4.03(Cu_4.01Mg_0.08)_Σ4.09[Cl_5.99(OH)_3.83O_0.18]_Σ10∙4H₂O. Dioskouriite-2M has the space group P2₁/c, a = 7.2792(8), b = 10.3000(7), c = 20.758(2) Å, β = 100.238(11)°, V = 1531.6(2) ų and Z = 4; dioskouriite-2O: P2₁2₁2₁, a = 7.3193(7), b = 10.3710(10), c = 20.560(3) Å, V = 1560.6(3) ų and Z = 4. The crystal structure (solved from single-crystal XRD data, R = 0.104 and 0.081 for dioskouriite-2M and -2O, respectively) is unique. The structures of both polytypes are based upon identical BAB layers parallel to (001) and composed from Cu²⁺-centered polyhedra. The core of each layer is formed by a sheet A of edge-sharing mixed-ligand octahedra centered by Cu(1), Cu(2), Cu(3), Cu(5) and Cu(6) atoms, whereas distorted Cu(4)(OH)₂Cl₃ tetragonal pyramids are attached to the A sheet on both sides, along with the Ca(OH)₂(H₂O)₄Cl₂ eight-cornered polyhedra, which provide the linkage of the two adjacent layers via long Ca−Cl bonds. The Cu(4) and Ca polyhedra form the B sheet. The difference between the 2M and 2O polytypes arises as a result of different stacking of layers along the c axis. The cation array of the layer corresponds to the capped kagomé lattice that is also observed in several other natural Cu hydroxychlorides: atacamite, clinoatacamite, bobkingite and avdoninite. The mineral is named after Dioskouri, the famous inseparable twin brothers of ancient Greek mythology, Castor and Polydeuces, the same in face but different in exercises and achievements; the name is given in allusion to the existence of two polytypes that are indistinguishable in appearance but different in symmetry, unit cell configuration and XRD pattern.

A new mineral, krasnoshteinite (Al₈[B₂O₄(OH)₂](OH)₁₆Cl₄⋅7H₂O), was found in the Verkhnekamskoe potassium salt deposit, Perm Krai, Western Urals, Russia. It occurs as transparent colourless tabular to lamellar crystals embedded up to 0.06 x 0.25 x 0.3 mm in halite-carnallite rock and is associated with dritsite, dolomite, magnesite, quartz, baryte, kaolinite, potassic feldspar, congolite, members of the goyazite–woodhouseite series, fluorite, hematite, and anatase. D_meas = 2.11 (1) and D_calc = 2.115 g/cm³. Krasnoshteinite is optically biaxial (+), α = 1.563 (2), β = 1.565 (2), γ = 1.574 (2), and 2V_meas = 50 (10)°. The chemical composition (wt.%; by combination of electron microprobe and ICP-MS; H₂O calculated from structure data) is: B₂O₃ 8.15, Al₂O₃ 46.27, SiO₂ 0.06, Cl 15.48, H₂O_calc. 33.74, –O=Cl –3.50, totalling 100.20. The empirical formula calculated based on O + Cl = 33 apfu is (Al_7.87Si_0.01)_Σ7.88[B_2.03O₄(OH)₂][(OH)_15.74(H₂O)_0.26]_Σ16[(Cl_3.79(OH)_0.21]_Σ4⋅7H₂O. The mineral is monoclinic, P2₁, a = 8.73980 (19), b = 14.4129 (3), c = 11.3060 (3) Å, β = 106.665 (2)°, V = 1364.35 (5) ų, and Z = 2. The crystal structure of krasnoshteinite (solved using single-crystal data, R₁ = 0.0557) is unique. It is based upon corrugated layers of Al-centered octahedra connected via common vertices. BO₃ triangles and BO₂(OH)₂ tetrahedra share a common vertex, forming insular [B₂O₄(OH)₂]⁴⁻ groups (this is a novel borate polyanion) which are connected with Al-centered octahedra via common vertices to form the aluminoborate pseudo-framework. The structure is microporous, zeolite-like, with a three-dimensional system of wide channels containing Cl^- anions and weakly bonded H₂O molecules. The mineral is named in honour of the Russian mining engineer and scientist Arkadiy Evgenievich Krasnoshtein (1937–2009). The differences in crystal chemistry and properties between high-temperature and low-temperature natural Al borates are discussed.