Medvedevite, KMn2+V5+2O6Cl⋅2H2O, is a new mineral discovered in the Toludskoe lava field, formed during the 2012–2013 Tolbachik fissure eruption. The mineral occurs as thin acicular transparent bright red crystals up to 0.15 mm. Medvedevite is associated with thénardite, halite, aphthitalite, leonite, kieserite, eugsterite and syngenite. The empirical formula calculated on the basis of 13+ positive charge units for the anhydrous part and 2H2O is (K1.02Na0.03)Σ1.05Mn2+0.95(V5+1.92S6+0.05Si0.04)Σ2.01O6.02Cl0.96⋅2H2O. The crystal structure of medvedevite was determined using single-crystal X-ray diffraction data: monoclinic crystal system, the space group is P21/c, a = 7.1863(2), b = 10.1147(3), c = 12.7252(4) Å, β = 106.243(3)°, V = 888.04(5) Å3, Z = 4 and R1 = 0.029. The concept of ‘structural unit’ and ‘interstitial complex’ could be applied to the crystal structure of medvedevite. The structural units in medvedevite are based on the high bond-valence V5+O5 polyhedra which share edges and link into [V2O6] chains elongated along the a axis. The interstitial complexes consist of Mn2+, K+ cations and H2O groups and occupy the interstices between structural units. The mineral is optically biaxial (+), with α =1.782(2), β = 1.786(2), γ = 1.792(2), 2V(calc) = 41° (λ = 589 nm). The seven strongest lines of the powder XRD pattern are [d, Å (I, %) (hkl)]: 7.79(100)(011); 5.70(11)(110); 4.75(14)(11$\bar{2}$); 3.89(29)(022); 3.25(53)(031); 2.958(79)(21$\bar{3}$); and 2.850(33)(220). The mineral has been named in honour of the Russian geologist and chemist Robert Alexandrovich Medvedev (1939–2005).

Reznitskyite, ideally CaMg(VO4)F, is a new mineral species of the tilasite group from the Arsenatnaya fumarole, Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It occurs as zones (usually up to 0.05 mm thick) in crystals of V- and P-containing tilasite or as homogeneous grains up to 0.1 mm across. It was found in polymineralic sublimate encrustations in association with minerals of the svabite–fluorapatite–pliniusite system and the schäferite–berzeliite, tilasite–isokite, wagnerite–arsenowagnerite and udinaite–arsenudinaite series. The mineral assemblage also includes calciojohillerite, diopside, forsterite, titanite, rhabdoborite-(V), rhabdoborite-(W), rhabdoborite-(Mo), ludwigite, powellite, scheelite, hematite, baryte and magnesioferrite. Reznitskyite is transparent or semi-transparent, colourless, with vitreous lustre. Dcalc. = 3.453 g cm–3. Under the microscope, in reflected light reznitskyite is grey, non-pleochroic, with very weak bireflectance (ΔR589 nm = 0.5%) and distinct anisotropy. Reznitskyite is the first vanadate with a titanite-type structure. It is monoclinic, space group C2/c, a = 6.6912(7), b = 8.9395(7), c = 7.0587(8) Å, β = 113.078(13)°, V = 388.43(8) Å3 and Z = 4. The strongest reflections of the powder X-ray diffraction pattern are [d in Å(I)(hkl)]: 3.082(100)(200), 3.250(66)($\bar{1}$12, 002), 2.631(44)(022), 2.854(34)($\bar{2}$02), 2.683(33)(130), 3.686(26)(021), 2.531(25)(220), 1.749(25)($\bar{3}$32, $\bar{2}$04) and 2.344(24)(131). Electron microprobe analysis gave (wt.%) MgO 20.44, CaO 26.83, P2O5 6.24, V2O5 21.09, As2O5 18.97, SO3 0.47, F 9.42, –O=F –3.97, with a total of 99.49. The empirical formula of reznitskyite, calculated on the basis of O+F = 5 atoms per formula unit, is: Ca0.97Mg1.03(V0.47As0.33P0.18S0.01)Σ0.99O3.99F1.01. Reznitskyite is a vanadate analogue of tilasite CaMg(AsO4)F and isokite CaMg(PO4)F. The mineral is named in honour of the outstanding Russian mineralogist Leonid Zinovievich Reznitsky (born 1938) who has made significant contribution to the mineralogy of vanadium.

An iron-rich vesigniéite, [Ba(Cu,Fe)3(VO4)2(OH)2] with Cu : Fe near 4 : 1, was identified in samples from the submarine-exhalative Gorob-Hope copper deposit, Namibia. The olive-colour mineral occurs as mammillary encrustations and vein fillings in the gossan zone of this deposit; it often has a brownish oxidation coating. The main X-ray lines are 3.21 Å (100) [204, 113], 2.72 Å (63) [313,002] and 2.94 Å (61) [020, 311]. The cell parameters are a = 10.236, b = 5.905, c = 14.253 Å and B = 103.71°. The formation of vesigniéite took place during the alteration of the ore under strongly alkaline and slightly reducing to oxidizing conditions. While copper and barium were derived from the submarine exhalative mineralisation, vanadium was leached from the countryrock, a micea schist.

A new mineral, yaroshevskite, ideally Cu9O2(VO4)4Cl2, occurs in sublimates collected from the Yadovitaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with euchlorine, fedotovite, hematite, tenorite, lyonsite, melanothallite, atlasovite, kamchatkite and secondary avdoninite, belloite and chalcanthite. Yaroshevskite forms isolated prismatic crystals, up to 0.1 × 0.15 × 0.3 mm in size, on the surface of euchlorine crusts. The mineral is opaque and black, with a reddish black streak and lustre between metallic and adamantine. Yaroshevskite is brittle, no cleavage was observed and the fracture is uneven. The Mohs hardness is ~3½ (corresponding to a mean VHN micro-indentation hardness of 172 kg mm -2) and the calculated density is 4.26 g cm-3. In reflected light, yaroshevskite is grey with a weak bluish hue. Pleochroism, internal reflections and bireflectance were not observed. Anisotropy is very weak. The composition (wt.%) determined by electron microprobe is: CuO 61.82, ZnO 0.53, Fe2O3 0.04, V2O531.07, As2O50.32, MoO3 1.56, Cl 6.23, O=Cl2 1.41; total 100.16. The empirical formula, calculated on the basis of 20 (O + Cl) anions is (Cu8.80 Zn0.07 Fe0.01)Σ 8.88(V3.87Mo0.12As0.03)σ 4.02O18.01Cl1.99. Yaroshevskite is triclinic, space group P, a = 6.4344(11), b = 8.3232(13), c = 9.1726(16) Å , α = 105.338(14), β = 96.113(14), γ = 107.642(1)°, V = 442.05(13) Å3 and Z = 1. The nine strongest reflections in the X-ray powder pattern [dobs in Å (I)(hkl)] are as follows: 8.65(100)(001); 6.84(83)(01); 6.01(75)(100); 5.52(60)(01); 4.965(55)(011); 4.198(67)(1); 4.055(65)(110); 3.120(55)(021); 2.896(60)(21,003,20). The crystal structure was solved by direct methods from single-crystal X-ray diffraction data and refined to R = 0.0737. The yaroshevskite structure is unique. It is based on corrugated layers made up of chains of edge-sharing flat squares with central Cu2+ cations [Cu(1), Cu(4) and Cu(5)]; neighbouring chains are connected via groups consisting of three Cu2+ -centred squares [two Cu(3) and Cu(6)]. Neighbouring layers are connected via pairs of Cu(2)O4Cl five-coordinate polyhedra and isolated VO4 tetrahedra. The structure of yaroshevskite can also be considered in terms of oxygen-centred tetrahedra: O(7)Cu4 tetrahedra are connected via common Cu(4) and Cu(5) vertices to form pyroxene-like chains [O2Cu6]∞. In this context, the structural formula can be written Cu3[O2Cu6][VO4]4Cl2. The mineral name honours the Russian geochemist Alexei A. Yaroshevsky (b. 1934) of Moscow State University.

Pottsite occurs in the oxide zone of a tungsten mine northwest of Potts, Lander County, Nevada, and is named for the locality. It occurs with scheelite, clinobisvanite, bismutite, and vanadinite. The colour is yellow, luster adamantine. Dobs. is 7.0, Dcalc. 7.31. Uniax (-) ω = 2.49, ɛ = 2.37. Microprobe analysis gave PbO 32.4, Bi2O3 34.0, V2O5 26.6; H2O by Penfield method 6.71% (total 99.71%), leading to HPbBi(VO4)2·2H2O. Crystals are tetragonal 14122, a = 11.084, c = 12.634Å. Strongest powder diffraction lines are 4.618 (9), 4.168 (3), 3.210 (4), 3.062 (10), 2.476 (4), 2.252 (3).

Mesaite (IMA2015-069), ideally (V2O7)3·12H2O, is a new mineral from the Packrat mine, Gateway district, Mesa County, Colorado, USA. Crystals of mesaite occur as orangish red blades up to 0.1 mm long and ∼10 μm thick. The streak is light pinkish orange and the lustre is vitreous, transparent. Mesaite has a brittle tenacity, {010} perfect cleavage; fracture is irregular, and no parting was observed. The mineral has a Mohs hardness ≈ 2. The measured density of mesaite is 2.74(1) g cm–3. Mesaite is biaxial (–), α = 1.760(calc), β = 1.780(5), γ = 1.795(5) in white light; the measured 2V value = 81(2)°. Dispersion is strong, r < v, and pleochroism is present in shades of brownish orange. Mesaite is monoclinic, P2/n, with a = 9.146(2), b = 10.424(3), c = 15.532(4) Å, β = 102.653(7)° and V = 1444.7(6) Å3. The strongest four diffraction lines in the powder diffraction pattern are [(dobs in Å, (Iobs), (hkl)]: 10.47 (100) (010), 2.881 (25) (132, 3̄12, 033, 310), 3.568 (24) (1̄14, 1̄23, 2̄13), 3.067 (17) (1̄24, 1̄32, 2̄23). The composition of mesaite was determined by electron microprobe, and yielded an empirical formula of Mn5.32Ca0.56Zn0.31V5.96As0.04O33H23.61 on the basis of 33 O atoms per formula unit (apfu).

The atomic arrangement of mesaite was solved and refined to R1 = 0.0600. The structure is formed of zigzag octahedral chains of edge-sharing Mn2+O6 octahedra. Oxygen atoms of the octahedra are shared with V2O7 groups, which link with adjacent octahedral chains to form {010} heteropolyhedral layers. The interlayer region contains Ca atoms and H2O groups. Each Ca bonds to two O6 atoms in the heteropolyhedral layer and to two fully occupied and six partially occupied O (H2O) sites in the interlayer, resulting in an effective Ca coordination of approximately seven. Similar zigzag chains of edge-sharing MnO6 octahedra decorated with V2O7 groups are also found in the mineral fianelite. Mesaite has beenapproved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2015-069). The name mesaite is conferred for Mesa County, Colorado, USA.

ATP-dependent Ca2+ uptake was studied in a subcellular fraction from Herpetomonas sp. prepared by mechanical disruption and using 45Ca2+ as a tracer. The uptake was stimulated by Ca2+ with a K0·5 of 0·1 μm and a Hill number (nH)=2·8±0·4. The Ca2+-dependent ATP hydrolysis was optimal at pH 7·0 and had a Ca2+ dependence identical to uptake. The uptake was highly stimulated by oxalate whereas calmodulin had no activating effect. ATP stimulated Ca2+ uptake with a biphasic pattern that resembled the curves described for the purified preparations of rabbit sarcoplasmic reticulum. The ATP stimulation is described as the sum of two Michaelis-Menten curves with Km1=0·25±0·19 μm and Km2=29·6±6·8 μm. GTP or UTP could also promote Ca2+ uptake, but with less efficiency than ATP. Vanadate inhibited the uptake with low apparent affinity. Thapsigargin and cyclopiazonic acid were almost ineffective. The Ca2+ uptake was insensitive to H+ ionophores and to bafilomycin suggesting no participation of acidocalcisomes. The results are comparable to those obtained using cells permeabilized with digitonin and using arsenaze III as Ca2+ indicator. The Ca2+ uptake activity described here seems to belong to the endoplasmic reticulum of Herpetomonas sp. and is suitable for further studies on the mechanisms of calcium homeostasis in parasites.