The crystal structure of "nickelalumite", ideally NiAl 4 (SO 4 )(OH) 12 (H 2 O) 3 , from the Kara-Tangi uranium deposit, Batken region, Kyrgyzstan, monoclinic, a 10.2567 (5) . Intercalated between the M-Al-OH sheets are layers of (SO 4 ) tetrahedra and (H 2 O) groups. All H atoms of (OH) and (H 2 O) groups were located, and details of hydrogen bonding are discussed. The structure of "nickelalumite" is similar to those of alvanite, ZnAl 4 (VO 3 ) 2 (OH) 12 (Traduit par la Rédaction) Mots-clés: "nickelalumite", structure cristalline, données de moicrosonde électronique, liaisons hydrogène.

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The new mineral saranchinaite, ideally Na2Cu(SO4)2, was found in sublimates of the Saranchinaitovaya fumarole, Naboko Scoria Cone, Tolbachik volcano, Kamchatka, Russia. Its discovery and study has enabled the characterization of the thermal decomposition of kröhnkite and provided an insight into the high-temperature behaviour of other kröhnkite-type materials. Saranchinaite is monoclinic, P21, a = 9.0109(5), b = 15.6355(8), c = 10.1507(5) Å, β = 107.079(2)°, V = 1367.06(12) Å3, Z = 8 and R1 = 0.03. Saranchinaite is a unique mineral in that two of its four independent Cu sites display a very unusual Cu2+ coordination environment with two weak Cu–O bonds of ~2.9–3.0 Å, resulting in [4+1+2] CuO7 polyhedra. Each of the Cu-centred polyhedra shares common corners with SO4 tetrahedra resulting in a [Cu4(SO4)8]8– framework with a complex channel system occupied by Na atoms. Saranchinaite is sensitive to moisture and transforms into kröhnkite within one week when exposed to open air at 87% relative humidity and 25°C. High-temperature X-ray diffraction studies were performed for both kröhnkite (from La Vendida mine, Antofagasta Region, Chile) and saranchinaite. During thermal expansion kröhnkite retains its strongly anisotropic character up to its full dehydration and the formation of saranchinaite at ~200°C, which then transforms back into kröhnkite after exposure to open air. The thermal expansion of saranchinaite is more complex than that of kröhnkite. Saranchinaite is stable up to 475°C with subsequent decomposition into tenorite CuO, thénardite Na2SO4 and unidentified phases.

Itelmenite, ideally Na2CuMg2(SO4)4, was found in a fumarole of the Naboko scoria cone of the Tolbachik volcano Fissure Eruption (2012–2013), Kamchatka Peninsula, Russia. Itelmenite occurs as irregularly shaped grains as well as microcrystalline masses associated with anhydrite, saranchinaite, hermannjahnite, euchlorine, thénardite, aphthitalite and hematite. Itelmenite is orthorhombic, Pbca, a = 9.568(2) Å, b = 8.790(2) Å, c = 28.715(8) Å, V = 2415.0(11) Å3 and Z = 4 (from single-crystal diffraction data). The nine strongest lines of the powder X-ray diffraction pattern are [d(I)(hkl)]: 7.9614(41)(102), 7.1803(32)(004), 5.9122(64)(112), 3.8455(87)(122), 3.6292(52)(214), 3.3931(62)(215), 3.0003(44)(027), 2.9388(100)(312) and 2.4975(56)(230). The chemical composition determined by the electron-microprobe analysis is (wt.%): Na2O 10.77, K2O 0.20, MgO 11.10, CuO 15.38, ZnO 5.61, SO3 56.42, total 99.48. The empirical formula based on O = 32 apfu is (Na3.93K0.05)Σ3.98Mg3.12(Cu2.19Zn0.78)Σ2.97S7.97O32. The simplified formula is Na2CuMg2(SO4)4 taking into account structural data. The crystal structure was solved by direct methods and refined to an agreement index R1 = 0.034 on the basis of 1855 independent observed reflections. The structure of itelmenite is based on a unique type of [A2+3(SO4)4]2– (A = Mg, Cu and Zn) heteropolyhedral framework with voids filled by Na+ cations.

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Aleutite, ideally [Cu5O2](AsO4)(VO4)·(Cu0.5□0.5)Cl, was found in the Yadovitaya fumarole of the Second scoria cone of the Great Fissure Tolbachik eruption, Kamchatka Peninsula, Russia. Aleutite occurs as individual crystals in the masses of polycrystalline anhydrite. Aleutite is monoclinic, C2/m, a = 18.090(2) Å, b = 6.2284(6) Å, c = 8.2465(9) Å, β = 90.597(2)°, V = 929.1(2) Å3 and Z = 4 (from single-crystal X-ray diffraction data). The empirical formula calculated on the basis of (As + V+Mo + Fe3+) = 2 atoms per formula unit is Сu5.40Zn0.05Ca0.01As1.09V0.84Mo0.04Fe0.03K0.05Pb0.02Rb0.01Cs0.01O9.97Cl1.07. The crystal structure was solved by direct methods and refined to an agreement index R1 = 0.066. Aleutite has a new structure type. Aleutite is unique amongst natural and synthetic copper vanadates and arsenates, as it has As5+ and V5+ cations ordered over two tetrahedral sites. The topology of ${}_\infty ^1 [{\rm Cu_5O_2}]^{6 +} $ oxocentred bands in aleutite is novel and has not been described before in minerals and synthetic materials. The structural architecture of the ${}_\infty ^1 [{\rm Cu_5O_2}]^{6 +} $ band in aleutite can be derived from a kagome network and represents a one-dimensional slice from it. In addition, aleutite is an interesting and complex example of a natural salt-inclusion phase.

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The new durangite-group mineral arsenatrotitanite, ideally NaTiO(AsO 4 ), was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great