In this issue

This New Mineral Names has entries for 11 new minerals, including cesiodymite, cryptochalcite, feodosiyite, fluoro-tremolite, itelmenite, ozerovaite, ramazzoite, redcanyonite, selivanovite, vanderheydenite, and wrightite.

Cryptochalcite* and Cesiodymite*

I.V. Pekov, N.V. Zubkova, A.A. Agakhanov, D.Y. Pushcharovsky, V.O. Yapaskurt, D.I. Belakovskiy, M.F. Vigasina, E.G. Sidorov and S.N. Britvin (2018) Cryptochalcite, K2Cu5O(SO4)5, and cesiodymite, CsKCu5O(SO4)5, two new isotypic minerals and the K-Cs isomorphism in this solid-solution series. European Journal of Mineralogy, 30(3), 593–607.

Cryptochalcite (IMA 2014-106), ideally K2Cu5O(SO4)5, and cesiodymite (IMA 2016-002), ideally CsKCu5O(SO4)5, both triclinic, were discovered in the fumarole sublimates of the Second scoria cone, Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Cryptochalcite was found in the Arsenatnaya (holotype) and Yadovitaya fumaroles, and cesiodymite was found only in the Arsenatnaya fumarole. The name cryptochalcite (Cyrillic: криптохальцит) is derived from the Greek κρυπτόζ, which means “concealed”, and χαλκόζ, which means “copper”. Cryptochalcite is a green copper mineral and occurs in intimate association with other green copper oxysulfates and is visually very similar to them, hence the name cryptochalcite means “concealed among other copper minerals.” The name cesiodymite (Cyrillic: цезиодимит) is derived from cesium and Greek δίδυμοζ, which means “a twin brother”: the mineral contains species-defining cesium and is a Cs-K-ordered analog of cryptochalcite. In the Arsenatnaya fumarole, cryptochalcite and cesiodymite belong to the same mineral assemblage and are found in association with eu-chlorine, chalcocyanite, dolerophanite, alumoklyuchevskite, anglesite, fedotovite, wulffite, langbeinite, aphthitalite, piypite, klyuchevskite, eleomelanite, anhydrite, dravertite, krasheninnikovite, calciolangbeinite, steklite, hematite, tenorite, pseudobrookite, As-bearing orthoclase, sylvite, halite, lammerite, lammerite-β, urusovite, and gold. In the Yadovitaya fumarole cryptochalcite was found in association with eu-chlorine, alumoklyuchevskite, langbeinite, steklite, fedotovite, hematite, and lyonsite. Cryptochalcite in Arsenatnaya occurs as poorly formed prismatic crystals or irregular grains up to 0.1 × 0.1 × 0.3 mm in size and their open-work aggregates up to 1.2 mm across. Cesiodymite forms crude prismatic or thick tabular crystals up to 0.05 × 0.1 mm × 0.15 mm or grains up to 0.3mm in size and their clusters, crusts or open-work aggregates up to 0.5 mm across. Both cryptochalcite and cesiodymite overgrow encrustations of euchlorine, sometimes anglesite, chalcocyanite, dolerophanite, alumoklyuchevskite or aphthitalite, which cover the basalt scoria altered by fumarolic gases. In Yadovitaya, cryptochalcite occurs as crude, roundish, usually blocky, prismatic crystals up to 0.08 × 0.2 mm in size and forming discontinuous crusts up to 1.5 × 2 cm in area and up to 0.2 mm in thickness, also covering the basalt scoria. The two new minerals are visually not distinguishable from one another. They are both transparent, and in aggregates sometimes translucent, light green to green in color, occasionally with a yellow hue. They both have a pale green streak, vitreous luster, and are brittle with an uneven fracture, and do not display any cleavage or parting. Their Mohs hardness is 3. Density was not measured due to the small size of the crystals and the porous nature of aggregates. Dcalc = 3.411 g/cm3 for cryptochalcite and Dcalc = 3.593 g/cm3 for cesiodymite. The new minerals are optically biaxial (–); with α = 1.610(3), β = 1.632(4), γ = 1.643(4), 2Vmeas = 65(5)°, 2Vcalc = 70° (λ = 589 nm) for cryptochalcite; and α = 1.61(1), β = 1.627(4), γ = 1.635(4), 2Vmeas = 70(10)°, 2Vcalc = 68° (λ = 589 nm) for cesiodymite. No dispersion of optical axis observed for both. Cryptochalcite and cesiodymite readily become dull and bluish for several minutes and slowly dissolve in H2O at room temperature. The Raman spectra of cryptochalcite and cesiodymite are generally similar but demonstrate some difference in wavenumbers and intensities of bands (cm–1): 1200–1050 [F2(ν3)-type stretching vibrations of SO42], 1030–950 [A1(ν1) symmetric stretching vibrations of SO42], 670–590 [F2(ν4) bending vibrations of SO42], 500–420 [E(ν2) bending vibrations of SO42], and 320–100 (lattice modes). The absence of bands with frequencies higher than 1200 cm–1 indicates the absence of groups with O–H, C–H, C–O, N–H, and N–O bonds in both new minerals. The averages of electron probe WDS analyses (4 for cryptochalcite and 5 for cesiodymite) are [wt% (range)]: Na2O 0.30 (0.22–0.38), K2O 9.55 (9.27–9.84), Rb2O 0.89 (0.80–1.02), Cs2O 0.90 (0.72–1.08), MgO 0.83 (0.68–1.05), CuO 33.95 (32.95–34.80), ZnO 9.14 (8.83–9.48), SO3 44.06 (43.17–44.60), total 99.62 for cryptochalcite; and K2O 5.47 (4.78–5.77), Rb2O 1.55 (1.39–1.67), Cs2O 10.48 (9.98–11.13), CuO 29.91 (29.08–30.62), ZnO 11.05 (10.45–11.67), SO3 40.74 (39.71–41.17), total 99.20 for cesiodymite. The empirical formulae based on O=21 pfu are: (K1.83Na0.09Rb0.09Cs0.06)Σ2.07(Cu3.86Zn1.02Mg0.19)Σ5.07S4.97O21 for cryptochalcite and (K1.14Rb0.16Cs0.73)Σ2.03(Cu3.69Zn1.33)Σ5.02S4.99O21 for cesiodymite. The strongest lines in the powder X-ray diffraction pattern are [d Å, (I%)]: 13.9 (30), 6.95 (100), 6.22 (45), 3.93 (65), 3.76 (30), 3.39 (30), 3.19 (35), 2.500 (4) for cryptochalcite; and 6.95 (54), 3.946 (100), 3.765 (37), 3.404 (39), 3.188 (50), 3.149 (27), 3.104 (28), 2.681 (31) for cesiodymite. The crystal structures of both new minerals were solved by direct methods and refined to R1 = 5.03% and R1 = 8.98% for cryptochalcite and cesiodymite, respectively. The new minerals are both triclinic, P1, Z = 4; cryptochalcite has: a = 10.0045(3), b = 12.6663(4), c = 14.4397(5) Å, α = 102.194(3), β = 101.372(3), γ = 90.008(3)°, V =1751.7 Å3 while cesiodymite: a = 10.0682(4), b = 12.7860(7), c = 14.5486(8) Å, α = 102.038(5), β = 100.847(4), γ = 89.956(4)°, V =1797.5 Å3. Cryptochalcite and cesiodymite are isostructural and share a novel structure type. Their crystal structures are based on the heteropolyhedral {Cu5O(SO4)5}2– framework composed by two types of alternating Cu2+-S-O polyhedral layers: {Cu2(SO4)2}0 and {Cu3O(SO4)}2+, which are connected via [SO4] tetrahedra. Cu-centered polyhedra are differently distorted octahedra, tetragonal pyramids and trigonal bipyramids. K and Cs cations occupy sites in the tunnels of the framework. Cryptochalcite and cesiodymite differ from one another only in the ratio and distribution of K and Cs between the A sites and in the coordination of A cations. The holotype specimens for both minerals are deposited in the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia. Yu.U.

Feodosiyite*

I.V. Pekov. N.V. Zubkova, V.O. Yapaskurt, D.I. Belakovskiy, I.S. Lykova, M.F. Vigasina, D.A. Ksenofontov, S.N. Britvin, E.G. Sidorov, D.A. Khanin and D.Yu. Pushcharovsky (2018) Feodosiyite, Cu11Mg2Cl18(OH)8·H2O, a new mineral from the Tolbachik volcano, Kamchatka, Russia. Mineralogical Magazine, 82(5), 1079–1088. Neues Jahrbuch für Mineralogie, Abhandlungen, 195/1, 27–39.

Feodosiyite (2015-063), ideally Cu11Mg2Cl18(OH)8·H2O, was discovered in the Glavnaya Tenoritovaya (“Major Tenorite”) fumarole, Second scoria cone, Northern Breakthrough (North Breach), Great Fissure eruption, Tolbachik volcano, Kamchatka, Russia. The new mineral was found in the moderately hot sulfate-chloride zone that occurs as a lenticular body ~1.5 m long and up to 0.2 m thick, on the northern flank of the fumarole. The gas temperature in this zone during collecting was about 100 °C. Feodosiyite is closely associated with belloite, avdoninite, sylvite, carnallite, chlorothionite, and dioskouriite. Other associated minerals are eriochalcite, halite, mitscherlichite, sanguite, chrysothallite, romanorlovite, mellizinkalite, flinteite, kainite, gypsum, sellaite, and incompletely studied K-Pb-Cu chloride; hematite, tenorite, and chalcocyanite are earlier, sublimate minerals. Feodosiyite occurs as well-formed or crude, tabular or prismatic crystals up to 0.015 × 0.04 × 0.05 mm, rarely up to 0.02 × 0.1 × 0.1 mm. Some crystals display thin polysynthetic twinning. Crystals form groups or crusts up to 1 mm. Interrupted incrustations up to 0.5 cm × 1 cm × 0.1 mm overgrow basalt scoria. The new mineral is bright green and transparent. It has a light green streak and vitreous luster. It is brittle, has uneven fracture and one direction of imperfect cleavage, and. Mohs hardness is ~3; Dmeas = 2.57 g/cm3, Dcalc = 2.563 g/cm3. Feodosiyite slowly dissolves in H2O at room temperature. In humid air the new mineral is unstable and alters to a bluish friable aggregate of hydrous Cu and Mg chlorides after several months. The mineral is optically biaxial (–) with α = 1.660(3), β = 1.690(5), γ = 1.718(5) (λ = 589 nm), 2Vmeas = 90(5)°, 2Vcalc = 86.5°. Dispersion of an optical axes is very strong, r > ν. Pleochroism is distinct: Z (grass green) > Y (light yellowish-green) > X (pale green with grayish hue). The Raman spectra of feodosiyite show bands (cm–1): 3500 to 3250 (O-H stretching), the strong narrow band at 3386 with the shoulder at 3461 (hydroxyl groups vibrations), the broad band at 3310 (vibrations of H2O); the relatively weak band at 1615 (H-O-H bending vibrations of H2O molecules); 898, 857, and 807 [O-H libration (Cu2+···O-H bending) modes]; 485 (Cu2+-O stretchings); 396 and 325 (Cu2+-O and Mg-O stretching modes); and the bands frequencies below 300 cm-1 probably correspond to lattice modes involving, in particular, Cu2+-Cl vibrations. The averaged 5-point WDS electron probe analyses [wt% (range)] is: MgO 5.39 (4.84–5.91), Cu 46.98 (45.46–49.29), Cl 35.42 (34.23–37.28), H2Ocalc 20.21, –O=Cl2 8.00, total 100.00 wt%. The empirical formula is Cu10.58Mg2.40Cl17.90 (OH)8.06·16.04H2O based on 42 O+Cl pfu. The strongest lines of the powder X-ray diffraction pattern are [d Å (I%; hkl)]: 11.87 (100; 100), 6.585 (15; 021), 5.969 (25; 102), 5.905 (16; 200), 5.231 (13; 121), 3.135 (8; 222,412,151), 2.924 (11; 333,251). The crystal structure of feodosiyite was solved by direct methods and refined to R1 = 8.67%. The new mineral is monoclinic, P21/c, a = 12.9010(6), b = 16.4193(5), c = 11.9614(5) Å, β = 113.691(6)°, V = 2320.20 Å3, and Z = 2. Feodosiyite has a unique crystal structure. It is based on layers of Cu2+-centred polyhedra. Cu2+ cations occupy six crystallographically non-equivalent sites that are placed in: distorted octahedra Cu(1,3,5)(OH)2Cl4, Cu(2)(OH)3Cl3, and Cu(6) (OH)2(H2O)Cl3, and distorted tetragonal pyramids Cu(4)(OH)2Cl3. Almost regular Mg(H2O)6 octahedra are isolated and linked with the layers of Cucentred polyhedra only by H-bonds. These octahedra and separate H2O molecules occur in the interlayer space. The new mineral name honors Feodosiy Nikolaevich Chernyshev (1856–1914) an outstanding Russian geologist, Academician of the Russian Academy of Sciences and Director of Russian Geological Committee in 1903–1914. The type specimen was sealed in a glass vial and is deposited in the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia. Yu.U.

Fluoro-tremolite*

R. Oberti, F. Cámara, F. Bellatreccia, F. Radica, A. Gianfagna and M. Boiocchi (2018) Fluoro-tremolite from the Limecrest-Southdown quarry, Sparta, New Jersey, USA: crystal chemistry of a newly approved end-member of the amphibole supergroup. Mineralogical Magazine, 82(1), 145–157.

Fluoro-tremolite, ideally ABCa2CMg5TSi8O22WF2, monoclinic, is the fluorine-analog of tremolite, the composition at the root of amphibole compositional space in all classification schemes used to date. Despite the frequent use of the term “fluorotremolite” (“fluorotremolite”, “fluortremolite”) in the mineralogical literature, this was remained a named amphibole (Burke and Leake 2004) and lacked a complete mineralogical description. The structural data for fluorine-rich tremolite to date was provided by Hawthorne and Grundy (1976) for a sample with F 0.66 apfu. The structure of synthetic fluoro-tremolite was first reported by Cameron and Gibbs (1973), During systematic characterization of amphiboles that still lack a complete mineral description, fluoro-tremolite was identified in a specimen G409 provided by Franklin Mineral Museum from the skarns at the Limecrest-Southdown quarry, Sparta, New Jersey, U.S.A. This specimen is now considered as holotype and has number 7710 at the same museum. Fluoro-tremolite as new mineral species was approved by CNMNC (IMA 2016-018). Coexisting phases in the holotype are calcite, chondrodite and pyrrhotite. Fluoro-tremolite occurs as prismatic light-greenish to colorless crystals forming gray to whitish green aggregates (the data on grain or crystal sizes, presence of inclusions, twinning are not provided). It has a gray streak and vitreous luster; the crystals are transparent and do not fluoresce under ultraviolet illumination. Density was not measured; Dcalc = 3.044 g/cm3. The mineral is biaxial (+), α = 1.5987(5), β = 1.6102(5), γ = 1.6257(5) (589 nm), 2Vmeas = 85(1)°, and 2Vcalc = 82° (the data on optical orientation is not provided). The FTIR spectrum of fluoro-tremolite is quite similar to that of synthetic fluoro-tremolite with 1.9 F apfu (Ishida et al. 2008). The bands (cm–1; sh – shoulder) are: 3672, 3658, 3643 (OH-stretching vibrations); 1132, 1104, 1059, 1039, 1017sh, 994, 954, 918 (Si–O-stretching vibrations), 880sh ([4[Al–O lattice vibrations), 755 (Si-O-Si deformations), 720, 712 (Si-O-[4]Al deformations), 687 (O-H libration), 663 (O-Si-O deformation), 544sh, 509 (M-O deformation). The detail analysis of peak positions in comparison with tremolite and synthetic fluoro-tremolite is given based on their crystal structures peculiarities. The average of three electron probe WDS analyses [wt% (range)] is: SiO2 55.52 (55.40–55.66), TiO2 0.14 (0.07–0.21), Al2O3 1.95 (1.86–2.09), Cr2O3 0.02 (0–0.05), FeOtot 2.44 (2.37–2.51), MnO 0.03 (0–0.08), MgO 22.74 (22.54–22.88), ZnO 0.10 (0–0.29), CaO 13.41 (13.34–13.51), Na2O 1.10 (1.06–1.16), K2O 0.11 (0.11–0.13), H2Ocalc 0.91, F 2.65 (2.52–2.76), Cl 0.03 (0.02–0.04); –O=F2 3.07, –O=Cl2 0.01, total 100.03. The amount of H2O was calculated based on single-crystal structure refinement and with the constraints of non-negative Fe2+ values and (OH + F + Cl) = 2 atoms pfu. The empirical formula is A(Na0.89K0.02)Σ0.30B(Ca1.99Na0.01)Σ2.00C(Mg4.70Fe0.282+Zn0.01Ti0.164+)Σ5.00T(Si7.68Al0.32)Σ8.00O22W(F1.16OH0.84)Σ2.00 based on 24 (O+F) apfu. The strongest lines in the calculated powder X-ray diffraction pattern are [dcalc Å (I%; hkl)]: 2.706 (100; 151), 6.98 (20; 004), 4.655 (37; 006), 3.555 (88; 020,311), 2.827 (100; 026,315,317), 2.055 (58; 331,602), 3.126 (67; 310), 2.531 (59; 202), 3.381 (57; 131), 2.940 (43; 151,221), 3.276 (37; 240), 2.337 (36; 351), 2.592 (35; 061), 2.731 (34; 331), 2.163 (34; 261). The crystal structure was refined to Rall = 1.7%. Fluoro-tremolite is monoclinic, C2/m, a = 9.846(2), b = 18.050(3), c = 5.2769(14) Å, β = 104.80(2)°, V = 906.7 Å3, Z = 2. The refined and analyzed crystal was assigned code 1082 in the amphibole database of the CNR-IGG in Pavia, Italy. The new structure and crystal-chemical data provided for synthetic fluoro-tremolite and tremolite from the type locality of Val Tremola (codes 751 and 361, respectively, in the same database). In the structure F is located in O(3) site, which is coordinated by the cations at the M(l) and M(3) sites. Cameron and Gibbs (1973) showed that the (OH)–F substitution significantly reduces the size of octahedra strip and hence the a and b cell parameters. The higher thermal stability of fluoro-tremolite was explained both by the higher bond-strength of the Mg–F bonds compare to Fe–F bonds. In fluoro-tremolite 1082 the significant contraction observed for the M(1)–O(2) and M(3)–O(1) bond distances although the O(1) and O(2) sites are not involved in the O(3)(OH)–O(3)F exchange. This shortening must be related to a general contraction of the O-layer due to the presence of F at the O(3) site. The A cations preferentially order at the A(m) subsite. D.B.

Comments: Fluor-tremolite is most likely more common mineral than it thought to be since in a number of an older analysis of tremolite fluorine was not measured. “Fluortremolite” with F 3.84 wt% (1.64 apfu) described by Petersen et. al. (1982) from Adirondack marbles (near Balmat, New York, U.S.A.). But no complete description was submitted to CNMNC IMA. The distribution of fluoro-tremolite in nature deserves an additional study. The presented paper provided a big set of a new structural data and a detail analysis of FTIR data based on the structure details. However, three analytical points of microprobe analysis seems a bit low when new mineral species (mostly differ by F content) is defined. Directly measured water content would also help to confirm fluorine dominance.

Itelmenite*

E.V. Nazarchuk, O.I. Siidra, A.A. Agakhanov, E.A. Lukina, E.Y. Avdontseva and G.A. Karpov (2018) Itelmenite, Na2CuMg2(SO4)4, a new anhydrous sulfate mineral from the Tolbachik volcano. Mineralogical Magazine, 82(6), 1233–1241.

Itelmenite (IMA 2015-047), ideally Na2CuMg2(SO4)4, orthorhombic, was discovered in 2014 in Saranchinaitovaya fumarole on the Naboko scoria cone (N55°46′06″, E160°18′59″, altitude 1650 m) of the Tolbachik volcano Fissure Eruption (2012–2013), Kamchatka Peninsula, Russia. The temperature of gases at the sampling location was ~600–620 °C. Itelmenite could be deposited directly from the gas or might form as a result of the interaction between gas and basalt scoria. Itelmenite occurs as irregularly shaped grains or microcrystalline masses associating with anhydrite, saranchinaite, hermannjahnite, euchlorine, thénardite, aphthitalite, and hematite. Itelmenite is light grayish-blue with a white streak and a vitreous luster. It is brittle with uneven fracture and no cleavage. Hardness and density were not measured due to the lack of suitable material; Dcalc = 3.10 g/cm3. The estimated Mohs hardness is 2–3. The mineral is unstable in air, is soluble in H2O at room temperature and slowly transforms into a hydrate in humid air. In transmitted plane-polarized light itelmenite is colorless, nonpleochroic. It is optically biaxial (+), α = 1.535(2), β = 1.555(2), γ = 1.585(2) (589 nm), 2Vcalc = 79.8°. The average of 10 spots electron-probe EDS analysis (using defocused 5 μm beam) is [wt% (range)]: Na2O 10.77 (9.97–11.23), K2O 0.20 (0–0.31), MgO 11.10 (9.10–11.75), CuO 15.38 14.78–15.71), ZnO 5.61 (4.15–6.05), SO3 56.42 (55.20–57.02), total 99.48. No other elements with Z > 9 were detected. The empirical formula based on O = 32 pfu is (Na3.93K0.05)Σ3.98 Mg3.12(Cu2.19Zn0.78)Σ2.97S7.97O32. The strongest lines of the powder X-ray diffraction pattern are [d Å (I%; hkl)]: 7.961 (41; 102), 7.180 (32;004), 5.912 (64; 112), 3.846 (87; 122), 3.629 (52; 214), 3.393 (62; 215), 3.000 (44; 027), 2.939 (100; 312), 2.498 (56; 230). Unit-cell parameters refined from the powder data are a = 9.575(5), b = 8.786(4), c = 28.78(1) Å, V = 2416 Å3. Single-crystal X-ray data obtained from the crystal 0.15 × 0.15 × 0.15 mm shows itelmenite is orthorhombic, space group Pbca, a = 9.568(2), b = 8.790(2), c = 28.715(8) Å, V = 2415.0 Å3, Z = 4. The crystal structure was solved by direct methods and refined to R1 = 0.034 for 1855 unique observed |Fo| ≥ 4σF reflections. There are four S fourfold-coordinated sites, two symmetrically independent Na sites Na1O10 and Na2O8 (Na1 site partly substituted by K), and three M sites. The M1 and M2 sites are in MO5 distorted tetragonal pyramidal coordination, whereas M3 site is in octahedral coordination (MO6). The M1 site is mostly occupied by Cu, the M2 site by Mg and Cu, and the M3 site mostly by Mg. The structure of itelmenite is based on unique [A32+(SO4)4]2– (A = Mg, Cu and Zn) heteropolyhedral framework with voids filled by Na+ cations. In this framework sulfate tetrahedra are packed into pseudo-layered arrangements perpendicular to the a axis. Na1O10 and Na2O8 polyhedra are also arranged in pseudo-layers, but perpendicular to the c axis. Each MO5 or MO6 polyhedron shares all common corners with sulfate tetrahedra. The framework can be split into A and B layers. The A layers are formed by M2O5 polyhedra and sulfate tetrahedra, whereas B layers consist of M3O6 octahedra and sulfate tetrahedra. Chains based on M1O5 polyhedra occur in the channels between the layers. The mineral is named for the Itelmens, an ethnic group who are the original inhabitants of the area around Tolbachik volcano and at Kamchatka Peninsula. Type material is deposited at the Mineralogical Museum, St. Petersburg State University, St. Petersburg, Russia. D.B.

Ozerovaite*

A.P. Shablinskii, S.K. Filatov, L.P. Vergasova, E.Yu. Avdontseva, S.V. Moskaleva and A.V. Povolotskiy (2019) Ozerovaite, Na2KAl3(AsO4)4, new mineral species from Tolbachik volcano, Kamchatka peninsula, Russia. European Journal of Mineralogy, 31(1), 159–166.

Ozerovaite (IMA 2016-019), ideally Na2KAl3(AsO4)4, orthorhombic, is a new mineral discovered in the fumaroles on the eastern side of the micrograben of the second cinder cone of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka Peninsula, Russia. The temperature of the volcanic gases in the fumarole at time of sampling (1983) was about 410–420 °C. The vent of fumarole was encrusted with ponomarevite, while piypite prevailed at a depth of 0.5 m. The bottom of the visible part of the fumarole was encrusted with sylvite associating with dolerophanite, euchlorine, lammerite, johillerite, urusovite, bradaczekite, filatovite, hatertite, hematite, ozerovaite, wrightite, and tenorite. Based on association, the formation temperature of the arsenate minerals is estimated as 500–600 °C. Ozerovaite forms tabular crystals of 0.04 × 0.02 × 0.004 mm average size in aggregates of 0.02–0.3 mm. Crystals are colorless to pale yellow, transparent, with white streak, vitreous luster, and good cleavage on {010}.The mineral is brittle. Hardness and density were not determined, due to the small crystal size; Dcalc = 3.439 g/cm3. The mineral is insoluble in water. It is colorless in transmitted plane-polarized light. Ozerovaite is optically biaxial (–), αcalc = 1.645, β = 1.667(2), γ = 1.674(2) (589 nm), 2Vmeas = 58(10)°. The average of four electron probe EDS analyses is [wt% (range)]: Na2O 7.71 (7.54–7.96), K2O 6.91 (6.59–7.34), As2O5 61.8 (60.68–62.59), P2O5 0.70 (0.66–0.75), CuO 1.18 (1.02–1.42), Al2O3 18.23 (17.88–18.67), Fe2O3 3.48 (3.24–4.05), ZnO 0.37 (0.31–0.42), total 100.04. No other elements were detected. The empirical formula based on 16 O pfu is (Na1.82K1.08)Σ2.90(Al2.62Fe0.32Cu0.12Zn0.02)Σ3.08 (As3.95P0.07)Σ4.02O16. The strongest lines of the X-ray powder diffraction pattern are [d Å (I%; hkl]: 10.37 (44; 020), 5.47 (47; 200), 4.84 (47; 220), 3.76 (17; 240), 3.07 (26; 061), 2.922 (83; 260), 2.824 (100; 202), 2.735 (71; 400). The unit-cell parameters refined from the powder data are a = 10.588(14), b = 20.94(2), c = 6.384(8) Å, V = 1415 Å3. Single-crystal X-ray data shows ozerovaite is orthorhombic: Cmca, a = 10.615(2), b = 20.937(3), c = 6.393(1) Å, V = 1420.9 Å3, Z = 4. The crystal structure refined to R1 = 0.031 based on 946 unique observed reflections. It is constructed of AlO6 octahedra and strongly distorted AsO4 tetrahedra, linked by the corners and edges. Adjacent layers, parallel to (010), are held together by KO6, NaO6, and NaO4 polyhedra. There are two AsO4 tetrahedra and two AlO6 octahedra in one asymmetric unit. Each Al(1)O6 octahedron is connected by the corners with four Al(2)O6 octahedra and six AsO4 tetrahedra, whereas an Al(2)O6 octahedron shares a common edge with an As(2)O4 tetrahedron, and shares corners with four other AsO4 tetrahedra and two Al(1)O6 octahedra. The crystal structure of ozerovaite is related to that of the A3B3(XO4)4 family, (A = Na, K, Sr; B = Al, Cr, Fe; X = As, P) and is similar to synthetic Na2KAl3(AsO4)2. The mineral name honors Nina Aleksandrovna Ozerova (1930–2012), for her contributions to geochemistry, geology, metallogeny, ecology and the eco-geochemistry of mercury. The type material is deposited at the Mineralogical Museum, St. Petersburg State University, St. Petersburg, Russia. D.B.

Ramazzoite*

A.R. Kampf, G.R. Rossman, C. Ma, D. Belmonte, C. Biagioni, F. Castellaro and L. Chiappino (2018) Ramazzoite, [Mg8Cu12(PO4) (CO3)4(OH)24(H2O)20][(H0.33SO4)3(H2O)36], the first mineral with a polyoxometalate cation. European Journal of Mineralogy, 30(4), 827–834.

Ramazzoite (IMA 2017-090), [Mg8Cu12(PO4)(CO3)4(OH)24(H2O)20] [(H0.33SO4)3(H2O)36], cubic, is a new polyoxometalate (POM) mineral from the Monte Ramazzo mine (44°28′5″N, 8°51′33″E), near Genova, Liguria, Italy. The mine was operating at least as early as 1465, mainly for copper, and later for iron sulfate and magnesium sulfate. The ore is hosted in ultramafic rocks (serpentinites) in contact with mafic rocks (basalt dikes and pillow lavas) of the Figogna Unit in the Ligurian Alps. Ramazzoite is a late-stage, secondary mineral that crystallized from low-temperature, aqueous solution. Ramazzoite is found on magnetite-rich matrix; associated minerals include chlorartinite, chrysotile, dypingite, goethite, lepidocrocite, nesquehonite, and an unidentified Mg sulfate-carbonate. Ramazzoite occurs as simple cubes up to about 0.15 mm on edge. Crystals are blue to greenish blue and transparent with a vitreous to oily luster and pale blue streak. Twins by merohedry were observed during structure determination. Crystals are very brittle with a conchoidal fracture. Perfect cleavage was observed on {100}. Mohs hardness is 2½ (scratch test). The mineral is non-fluorescent. Dobs = 1.98 g/cm3 (by floatation in methylene iodidetoluene) and Dcalc = 1.962 g/cm3. It is isotropic with n = 1.491(1) (white light). The mineral is soluble with mild effervescence in dilute HCl at room temperature. The Raman spectra (532 nm laser) show bands (cm–1; s – strong, w – weak, sh – shoulder) at: 3565s, 3455sh, 3259sh, 2936s [O–H stretching vibrations of H2O molecules and OH groups], 1469w, 1432w 1362w [ν3 double degenerate antisymmetric stretching vibrations of CO32 groups], 1086 [ν1 symmetric stretching vibrations of the CO32 groups or to the triply degenerate ν3 antisymmetric stretching vibrations of the PO43 and/or SO42 groups], 984s [ν1 symmetric stretching vibrations of the SO42 groups], 940w [ν1 symmetric stretching vibrations of the PO43 groups], 674w, 615w, 590w [triply degenerate bending vibrations of the PO43– and/or SO42 groups or to the bending modes of the CO32 group], 500s, 451sh [ν2 (δ) doubly degenerate bending vibrations of the PO43 and/or SO42 groups], <300 [probably connected with the Cu–O and Mg–O stretching and bending modes and lattice modes]. The average of five electron microprobe WDS analyses (three crystals) is [wt% (range) / normalized to 100%]: MgO 22.61 (20.82–24.05) / 16.73; CuO 30.30 (29.48–31.32) / 22.43; P2O5 3.38 (3.25–3.52) / 2.50; SO3 11.51 (11.00–12.23) / 8.52, CO2 – / 6.21 (based upon the structure), H2Ocalc (based upon 36 H2O in the interstitial unit to approximate the measured density) – / 43.60, total 99.99. The empirical formula calculated on the basis of 1 P apfu is: [(Mg8.00)(Cu8.00Mg3.78)(PO4) (CO3)4(OH)24(H2O)20][(H0.65S1.01O4)3 (H2O)36]. The strongest X-ray powder diffraction lines are [d Å (I%; hkl)]: 13.37 (100; 100), 9.43 (24; 110), 4.224 (8; 310), 4.043 (11; 311), 3.252 (9; 322), and 2.857 (9; 332). Unit-cell parameters refined from the powder data with whole-pattern fitting are a = 13.393(3) Å, V = 2402 Å3. Single-crystal X-ray data on a crystal of 0.15 × 0.15 × 0.15 mm (R1 = 0.06438 for 802 I > 2σI reflections; Rall = 0.0659 for 848 reflections) shows ramazzoite is cubic, P43m, a = 13.3887(10) Å, V = 2400 Å3, Z = 1. Ramazzoite is a novel POM (polyoxometalate). The POM in ramazzoite has at its center a PO43 group, which is surrounded by twelve Cu-centered octahedra in a Keggin α-isomer configuration. The Keggin-like core of the POM is “capped” by eight Mg-centered octahedra, each sharing the three edges of one face with edges of three separate Cu-centered octahedra. On the periphery of the POM there are 12 CO32 groups, only ⅓ occupied, so there are 4 CO32 groups pfu. H2O groups are in the interstitial region to fulfill its valence balance. The POM structural unit has the ideal formula [Mg8Cu12(PO4)(CO3)4(OH)24(H2O)20]5+. The interstitial portion of the structure contains one fully occupied S site at a threefold special position, plus H2O groups. The interstitial region has the stoichiometry [(H0.33SO4)3(H2O)36]. Ramazzoite is named for the locality, the Monte Ramazzo mine. The description is based upon two cotype specimens deposited in the Natural History Museum of Los Angeles County, Los Angeles, California, U.S.A., catalogue numbers 66691 and 66692. F.C.

Redcanyonite*

T.A. Olds, J. Plášil, A.R. Kampf, P.C. Burns, B.P. Nash, J. Marty, T.P. Rose and S.M. Carlson (2018) Redcanyonite, (NH4)2Mn[(UO2)4O4(SO4)2] (H2O)4, a new zippeite-group mineral from the Blue Lizard mine, San Juan County, Utah, USA. Mineralogical Magazine, 82(6), 1261–1275.

Redcanyonite (IMA 2016-082), (NH4)2Mn[(UO2)4O4(SO4)2](H2O)4, monoclinic, is a new member of the zippeite group, which occurs underground in the Blue Lizard mine, on the northern edge of the Red Canyon, White Canyon district, San Juan County, Utah, U.S.A. (37°33′26″N, 110°17′44″W). Secondary uranium mineralization in Red Canyon is often localized and most prevalent within organic-rich beds that are laced with uraninite and sulfides. The source of NH4+ is inferred from decomposition of organic material. Redcanyonite occurs intimately with ammoniozippeite in several specimens. Other associated secondary minerals include bobcookite, brochantite, devilline, gypsum, johannite, posnjakite, natrozippeite, pentahydrate, and pickeringite. Redcanyonite occurs as radial aggregates (up to 1 mm in diameter) of needles and blades individually measuring up to 0.2 mm long. Crystals are flattened on {010} and elongated on [100], and exhibit the forms {001}, {010}, {101}, and {101}. Many crystals are twinned by 180° rotation on [100]. Crystals are translucent with a vitreous luster, pale orange streak, and are non-fluorescent under both long-wave and short-wave ultraviolet illumination. Mohs hardness is ~2. Crystals of redcanyonite are brittle with perfect {010} cleavage and uneven fracture. The density was not measured due to the lack of material; Dcalc = 4.633 g/cm3 (based on the empirical formula) and 4.688 g/cm3 (for the ideal formula). Optically is biaxial (+), with α = 1.725(3), β = 1.755(3), and γ = 1.850(5) (white light); 2Vmeas = 60(2)°, 2Vcalc = 61.3°; X = b, Yc*, Za. Dispersion of an optical axes is very strong, r < ν. The mineral is pleochroic with X = orange, Y = yellow and Z = orange; Y << X < Z. Attenuated total reflectance (ATR) Fourier-transform infrared (FTIR) show the following bands (cm–1; vs – very strong, s – strong, w – weak, sh – shoulder): broad between ~3500 and ~2800 (ν O–H stretching vibrations of hydrogen-bonded H2O, overlapped with N–H stretching vibrations from interlayer NH4+ molecules), 1615w [ν2 (δ)-bending vibration of hydrogen-bonded crystalline H2O], 1408s (N–H bending vibration of NH4+ molecules), 1155, 1140, and 1084 [split triply degenerate ν3 (SO4)2– antisymmetric stretching vibration], 1100–1000 [ν1 (SO4)2– symmetric stretch enveloped by the ν3 (UO2)2+ antisymmetric stretch], 940vs [ν3 antisymmetric stretch of (UO2)2+], 836w [ν1 symmetric stretch of (UO2)2+]. Raman spectroscopy (785 nm laser) show the following bands (cm–1; vs – very strong, s – strong, w – weak, sh – shoulder): 1263w, 1158w, and 1097w (triply degenerate ν3 (SO4)2– antisymmetric stretching vibrations), 1013 [ν1 (SO4)2– symmetric stretch], 819, 809sh [ν1 symmetric stretch of (UO2)2+], 666w and 601w [split, triply degenerate ν4(δ)(SO4)2– bending vibrations], 506, 464, and 418 [split doubly degenerate ν2(δ)(SO4)2– bending vibrations], 354 and 329 [ν(U–Oequatorial) stretching vibrations], 284 and 261 [ν2(δ)U–O–U bending modes], and 206, 176, 150, and 127 (external lattice vibration modes and UO22+ translations and rotations). The mineral is easily soluble in room-temperature dilute HCl. The average of five electron microprobe WDS analyses is [wt% (range)]: (NH4)2O 3.41 (2.84–4.20), P2O5 0.10 (0.00–0.16), SO3 10.28 (9.45–10.77), MnO 2.26 (1.72–2.87), CuO 0.46 (0.11–0.71), ZnO 0.34 (0.12–0.49), UO3 74.27 (73.13–75.13), H2O 5.10 (from the structure), total 96.22. The empirical formula, calculated on the basis of 4 U and 24 O atoms pfu is (NH4)2.02(Mn0.49Cu0.09Zn0.06)Σ0.64H0.72+[(UO2)4O4(S0.99P0.01O4)2](H2O)4. The strongest lines in the powder X-ray diffraction pattern are [d Å (I%; hkl)]: 8.55 (21; 001), 7.19 (100; 020), 3.600 (33; 220,131,040), 3.453 (56; 202), 3.112 (72; 221), 2.657 (23; 023), and 2.491 (21; 242). Unit-cell parameters refined from the powder data are a = 8.665(2), b = 14.359(2), c = 8.834(2) Å, β = 104.190(5)°, and V = 1065.5 Å3. The crystal structure was solved by charge-flipping method using single crystal X-ray diffraction on a crystal of 0.030 × 0.025 × 0.002 mm (R1 = 0.075 for 1079 I>2σI reflections; Rall = 0.0493 for 1382 reflections). Redcanyonite is monoclinic, C2/m, a = 8.6572(17), b = 14.155(3), c = 8.8430(19) Å, β = 104.117(18)°, and V = 1050.9 Å3, Z = 2. The crystal of redcanyonite chosen for diffraction was twinned, with twin law (1,0,½/0,1,0/0,0,1). In the redcanyonite structure the uranyl pentagonal bipydramids and sulfate tetrahedra are linked to form the well-known zippeite type, which consists of zigzag chains of uranyl pentagonal bipyramids two-polyhedra wide that extend along [100], where individual chains link to form a sheet by sharing equatorial vertices with sulfate tetrahedra. Each sulfate tetrahedron links four unique bipyramids (two bipyramids of two separate chains) and propagates the zippeite-type sheet along [001]. Individual sheets stack parallel to (010), which corresponds to the excellent cleavage. Sheets are linked through a network of H bonds that emanate from interstitial water and ammonium groups. Redcanyonite is named after Red Canyon in southeast Utah and alludes to the red and orange hues of iron-stained sandstones within the canyon, which are also adopted in the striking color of the new mineral. Red Canyon is the type locality for 22 recently described uranium minerals with several more currently under study. Six co-type specimens are deposited in the collections of the Natural History Museum of Los Angeles County (California, U.S.A.), under the catalogue numbers 66293, 66294, 66295, 66296, 66297, and 66298. F.C.

Selivanovaite*

Y.A. Pakhomovsky, T.L. Panikorovskii, V.N. Yakovenchuk, G.Yu. Ivanyuk, J.A. Mikhailova, S.V. Krivovichev, V.N. Bocharov and A.O. Kalashnikov (2018) Selivanovaite, NaTi3(Ti,Na,Fe,Mn)4[(Si2O7)2O4 (OH,H2O)4]·nH2O, a new rock-forming mineral from the eudialyte-rich malignite of the Lovozero alkaline massif (Kola Peninsula, Russia). European Journal of Mineralogy, 30(3), 525–535.

Selivanovaite (IMA 2015-126), NaTi3(Ti,Na,Fe,Mn)4[(Si2O7)2O4 (OH,H2O)4]·nH2O, triclinic, is a new titanosilicate of the murmanite group (seidozerite supergroup) found in drill cores of medium-grained trachytoid eudialyte malignite of Mt. Kedykvyrpakhk, at the horizon 850–1050 m (50–150 m below day surface (Alluaiv set of the giant Lovozero loparite–eudialyte Ta-Nb-REE-Zr deposit). The rock consists mainly of euhedral microcline-perthite (up to 1.5 cm), nepheline (up to 1 cm) and manganoeudialyte crystals (up to 0.5 cm) cemented by fine-acicular aegirine with poikilitic laths of minor lamprophyllite and selivanovaite (up to 10 %; 3% in average). The mean modal composition of the rock is Kfs40Nph30Aeg20Eud10. Other minor rock-forming minerals include sodalite, natrolite, and magnesioarfvedsonite. Characteristic accessory minerals are murmanite, loparite-(Ce), pyrochlore, thorite, anatase, baryte, rhabdophane-(Ce), pyrrhotite, chalcopyrite, pyrite, chlorbartonite, djerfisherite, sphalerite, and löllingite. Selivanovaite forms dark-orange vitreous to greasy anhedral platy metacrysts up to 8 mm with numerous poikilitic inclusions of aegirine and magnesioarfvedsonite. It is translucent in thin plates and has a brownish-white streak. The cleavage is perfect on {001} and weak on {110}, the fracture is stepped. The mineral is brittle with Mohs hardness ~3. Dmeas = 3.15(3) (Clerici solution); Dcalc = 3.34(3) g/cm3. Selivanovaite dissolves slowly in 10% cold HCl. In transmitted light, selivanovaite is brown and non-pleochroic. It is biaxial (+), α = 1.79(1), β = 1.81(1), γ = 1.87(1) (589 nm), 2Vmeas = 40(5)°, 2Vcalc = 57.3°; Z^c = 5–10°; dispersion of optical axes was not observed. The Raman spectrum of selivanovaite (the mineral is very unstable under the laser beam) shows bands (cm–1): 1600 (symmetric bending vibrations of H2O); in region between 690 and 434 (symmetric and antisymmetric bending vibrations of SiO4); 780, 930 (Si–O stretching); 610, 281, 180 (symmetric stretching and bending vibrations of the TiO6, FeO6, and MgO6 groups); 77, 104, 147 – lattice modes. The average of WDS electron probe analysis (5–6 points on each of 3 crystals with defocused beam moved during the analysis to avoid water loss due to instability the mineral under the beam) [wt% (range)] is: Na2O 5.45 (4.06–7.17), MgO 0.59 (0.41–0.70), Al2O3 0.04 (0–0.11), SiO2 25.55 (23.38–27.83), K2O 0.63 (0.17–1.28), CaO 1.68 (1.35–2.34), TiO2 31.17 (26.77–36.95), MnO 2.64 (2.29–2.89), Fe2O3 6.63 (3.10–10.94), ZrO2 2.31 (2.01–2.71), Nb2O5 6.69 (6.04–7.02), H2O 17.0 (by the Penfield method), total 100.38. The empirical formula calculated on the basis of Si = 4 pfu is: (Na1.65Mn0.35Ca0.28 Zr0.18Mg0.14K0.13)Σ2.73(Ti3.67Fe0.783+Nb0.47Al0.01)Σ4.93[Si4O19.72]·8.87H2O. The structure refinement is giving the H2O content ~1.72 pfu. That implies the presence of a significant amount of nonstructural (adsorbed) water up to 7 H2O pfu). Similar to murmanite, the non-structural H2O can be easily eliminated in vacuum or under even mild heating. There are no clear relations between different cation contents, but the mineral enriched with Fe at the expense of Ti and Na compare to coexisting murmanite due to the isomorphic substitutions 2Na+ + Ti4+ ↔ ☐ + 2Fe3+ and/or Na+ + Ti4+ ↔ Ca2+ + Fe3+. The strongest X-ray powder-diffraction lines [d Å (Irel%; hkl)] are: 11.43 (100; 001), 6.37 (25; 111), 5.73 (15; 002), 4.208 (16; 211), 3.108 (35; 221), 3.043 (20; 104), 2.596 (17; 014). Unit-cell parameters refined from the powder patterns are: a = 8.673(5), b = 8.694(1), c = 12.21(1) Å, α = 92.70(5), β = 108.52(1), γ = 105.42(1)°, V = 833 Å3, Z = 2. The single-crystal cell parameters are practically identical: a = 8.673(5), b = 8.694(3), c = 12.21(1) Å, α = 92.70(5), β = 108.46(7), γ = 105.40(4)°. The single-crystal X-ray data for a crystal 0.015 × 0.015 × 0.002 mm shows extremely weak diffraction. The structure was refined to R1 = 0.193 (Rint = 0.165) for 2881 independent Fo>4σ(Fo) reflections in the space group P1; Z = 2. The crystal structure of selivanovaite is closely related to those of murmanite-group minerals and consists of the HOH-layers with the composition [N2M5Si4O18(OH)3] (M = Ti, Nb, Fe and Mn, N = Na, K, Ca, Mn, Mg, and Zr) connected by additional N-centered octahedra with H2O molecules between them. It differs from vigrishinite by geometry and stereochemistry of the H-sheets. The name honors Ekaterina A. Selivanova (b. 1967), of the Kola Science Centre of the Russian Academy of Sciences, for her contribution to the mineralogy of alkaline complexes. D.B.

Vanderheydenite*

P. Elliott and U. Kolitsch (2018) Description and crystal structure of vanderheydenite, Zn6(PO4)2(SO4)(OH)4·7H2O, a new mineral from Broken Hill, New South Wales, Australia. European Journal of Mineralogy, 30(4), 835–840.

Vanderheydenite (IMA 2014-076), ideally Zn6(PO4)2(SO4) (OH)4·7H2O, monoclinic, is a new mineral from the Block 14 Opencut, Broken Hill, New South Wales, Australia. The Broken Hill ore body consists of massive, recrystallized sphalerite- and galena-rich sulfide hosted within a unit of gneiss known as the Potosi Gneiss. The lower portion of the oxidized zone grades into silver-rich supergene mineralization, comprising coronadite, quartz, kaolinite, and goethite. Between this and the sulfide zone is an irregular zone of cerussite, whose boundary with the sulfide zone is marked by a band of leached sulfides, where vanderheydenite was found in a highly weathered sulfide ore in the Block 14 Opencut. The new mineral formed in cavities as a result of the release of Zn, S, As, and P from the breakdown of sphalerite, galena, and fluorapatite. Associated minerals are colorless to white prisms of pyromorphite, colorless crystals of anglesite, and aggregates of colorless to white crystals of liversidgeite. Vanderheydenite occurs as aggregates of colorless crystals up to 0.5 mm across. Individual crystals are thin blades that are flattened on {100} and are up to 0.4 mm in width and 0.05 mm in thickness. Crystal forms are major {100}, {010}, and {021}, resulting in a pseudohexagonal outline. Vanderheydenite has a white streak and a vitreous luster; it does not fluoresce under ultraviolet light. Mohs hardness is ~3. Cleavage was not observed. Density was not measured; Dcalc = 3.12 g/cm3 (based on the empirical formula) and 3.06 g/cm3 (for the ideal formula). It is optically biaxial (–), α = 1.565(4), β = 1.580(4), γ = 1.582(4); (white light); 2Vcalc = 39.8°. The FTIR spectra show as main bands (cm–1): a broad band from ~3674 to ~2720 (O–H-stretching vibrations), 1636 (ν2 H–O–H bending of H2O groups), 1056 (ν3 vibration of the SO4 tetrahedra, overlapping with ν3 vibration of the PO4 tetrahedra), 968 (ν1 vibration of the SO4 tetrahedra, overlapping with ν1 vibration of the PO4 tetrahedra of SO42 ions), 885 and 853 [ν3 vibrations of the AsO4 tetrahedra). The average of 13 WDS electron probe analyses is [wt% (range)]: ZnO 55.63 (54.49–56.68), CuO 0.07 (0.00–0.21), FeO 0.11 (0–0.28), MnO 0.06 (0–0.15), P2O5 14.18 (13.10–15.29), As2O5 4.33 (3.14–5.18), SO3 8.71 (7.31–9.85), H2O 18.31 (from the structural formula), total 101.40. The empirical formula was calculated on the basis of 23 oxygen atoms is (Zn5.99Cu0.01Fe0.01Mn0.01)Σ6.02[(PO4)1.75(AsO4)0.33]Σ2.08(SO4)0.95(OH)3.91·6.96H2O. The strongest lines of the powder X-ray diffraction pattern [d Å (I%; hkl)] are: 9.826 (57; 020), 7.296 (20; 011), 6.134 (100; 021), 3.368 (10; 032,150), 3.069 (9; 210,042). The unit-cell parameters calculated from the powder data are: a = 6.209(2), b = 19.637(7), c = 7.822(3) Å, β = 90.672(2)°, V = 953.64 Å3. The crystal structure was solved by direct methods using single crystal X-ray diffraction on a crystal of 0.070 × 0.050 × 0.005 mm (R1 = 0.0497 for 939 Fo>4σFo reflections; Rall = 0.1228 for 1920 reflections). Vanderheydenite is monoclinic, P21/n, a = 6.2040(12), b = 19.619(4), c = 7.7821(16) Å, β = 90.67(3)°, V = 947.1 Å3, Z = 2. The crystal structure of vanderheydenite is unique and is comprised of zigzag sheets of Znφ6 octahedra, Znφ5 trigonal bipyramids and TO4 tetrahedra. Alternate Zn1φ6 (w = O, OH, or H2O) and Zn2φ6 octahedra share trans edges to form a [Mφ4] chain that extends parallel to [100]. The Zn3φ5 trigonal bipyramids share an edge with both Zn1φ6 and Zn2φ6 octahedra and link to a second [Mφ4] chain by corner sharing, forming zigzag sheets in the (010) plane. Sheets are decorated by corner-sharing T1O4 tetrahedra. Sheets link in the [011] direction by T2O4 tetrahedra which share corners with Zn1φ6 and Zn2φ6 octahedra. Interstitial channels between the sheets extend parallel to the a-direction and are occupied by H2O groups, which are strongly to weakly hydrogen bonded. The mineral is named in honor of Arnold van der Heyden who worked as a mine geologist at Broken Hill for the former Minerals Mining and Metallurgy Ltd from December 1985 until June 1991. The holotype specimen [also the holotype specimen for liversidgeite, Zn6(PO4)4·7H2O] is deposited in the South Australian Museum, Adelaide, South Australia. F.C.

Wrightite*

A.P. Shablinskii, S.K. Filatov, L.P. Vergasova, E.Yu. Avdontseva and S.V. Moskaleva (2018) Wrightite, K2Al2O(AsO4)2, a new oxo-orthoarsenate from the Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik volcano, Kamchatka peninsula, Russia. Miner-alogical Magazine, 82(6), 1243–1251.

Wrightite (IMA 2015-120), ideally K2Al2O(AsO4)2, orthorhombic, is a new mineral discovered in 1983 in one of fumarole on the east side of the micrograben at the Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik volcano, Kamchatka peninsula, Russia. The temperature of the volcanic gases in the fumarole was 410–420 °C and the vent was encrusted with ponomarevite, while piypite prevailed at a depth of 0.5 m. The bottom of the visible part of the fumarole was encrusted with sylvite associating with dolerophanite, euchlorine, lammerite, johillerite, urusovite, bradaczekite, filatovite, hatertite, hematite, ozerovaite, and tenorite. Based on association, the formation temperature of the arsenate minerals is estimated as 500–600 °C. Wrightite forms light yellow aggregates of transparent tabular colorless to light yellow crystals, with an average size 0.05 × 0.03 × 0.005 mm. Well-formed crystals are very rare. The mineral has vitreous luster and white streak. It is brittle. Cleavage or parting are not reported. Hardness and density were not determined due to the small crystal size; Dcalc = 3.50 g/cm3. Wrightite is optically is biaxial (−), α = 1.679(2), β = 1.685(2), γ (calc) = 1.687; 2V = 62(10)° (λ = 589 nm). The X and Y directions are in the plane of tabular crystals. Tabular crystals have a positive elongation. No pleochroism is observed. The average of electron probe EDS analyses on 11 grains [wt% (range)] is: Na2O 2.72 (2.39–3.03), K2O 18.31 (17.75–18.65), As2O5 51.89 (51.19–52.99), Al2O3 21.14 (17.06–23.41), Fe2O3 4.39 (1.07–9.06), total 98.45. No other elements were detected. The empirical formula based on O=9 pfu is (K1.69Na0.38)Σ2.07(Al1.80Fe0.24)Σ2.04As1.96O9. The strongest lines in the powder X-ray diffraction pattern [d Å (I%; hkl)] are: 8.77 (36; 002), 6.01 (18; 102), 4.458 (17; 111), 4.097 (16; 112), 4.010 (19; 201,013), 3.875 (19; 104), 3.003 (16; 204); 2.972 (100; 015). The unit-cell parameters, derived from a powder XRD data are a = 8.230(5), b = 5.555(4), c = 17.584(1) Å, V = 803.9 Å3. Single-crystal X-ray data shows wrightite is orthorhombic, space group Pnma, a = 8.2377(3), b = 5.5731(6), c = 17.683(1) Å, V = 811.8 Å3, Z = 4. The crystal structure (refined to R1 = 0.043 for the 1924 independent reflections) is similar to that of the synthetic analog NaKAl2O(AsO4)2 and consists of Al2O(AsO4)2 layers in the (001) plane with clusters of edge-sharing AlO6 octahedra. Each layer contains two independent isolated AsO4 tetrahedra and two AlO6 octahedra. AlO6 octahedra are linked by edges, forming zigzag chains along the b axis inside the Al2O(AsO4)2 layer. Eightfold- and sixfold-coordinated K atoms are located in the interlayer space between Al2O(AsO4)2 layers. The mineral name honors Adrian Carl Wright (b. 1944), Emeritus Professor at the University of Reading, U.K., a well-known expert in structural studies of glass-forming systems. The type material is deposited at the Mineralogical Museum, St. Petersburg State University, St. Petersburg, Russia. D.B.

*
All minerals marked with an asterisk have been approved by the IMA CNMMC.
For a complete listing of all IMA-validated unnamed minerals and their codes, see http://pubsites.uws.edu.au/ima-cnmnc/.
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