In this issue

This New Mineral Names has entries for 6 new minerals, including, beusite-(Ca), graftonite-(Ca), graftonite-(Mn), hyršlite, magnesiobeltrandoite-2N3S, and zincovelesite-6N6S.

Beusite-(Ca), Graftonite-(Ca)* and Graftonite-(Mn)*

F.C. Hawthorne, M.A. Wise, P. Černý, Y. Abdu, N.A. Ball, A. Pieczka, and A. Włodek (2018) Beusite-(Ca), ideally CaMn22+(PO4)2, a new graftonite-group mineral from the Yellowknife pegmatite field, Northwest Territories, Canada: Description and crystal structure. Mineralogical Magazine, 82(6), 1323–1332.

A. Pieczka, F.C. Hawthorne, N. Ball, Y. Abdu, B. Gołębiowska, A. Włodek, and J. Żukrowski (2018) Graftonite-(Mn), ideally M1MnM2,M3Fe2(PO4)2, and graftonite-(Ca), ideally M1CaM2,M3Fe2(PO4)2, two new minerals of the graftonite group from Poland. Mineralogical Magazine, 82(6), 1307–1322.

Three new monoclinic minerals of the graftonite group, earlier considered as the “graftonite–beusite series” (Hawthorne and Pieczka 2018) were recently discovered: beusite-(Ca) (IMA 2017-051) ideally M1CaM2,M3Mn2(PO4)2, graftonite-(Mn) (IMA 2017-050), ideally M1MnM2,M3Fe2(PO4)2, and graftonite-(Ca) (IMA 2017-048), ideally M1CaM2,M3Fe2(PO4)2. All new minerals occur in beryl–columbite–phosphate subtype of zoned rare-element pegmatites. Beusite-(Ca) was found in a small dike, which cuts an interlayered sequence of amphibolite and granodiorite in the Archean Yellowknife pegmatite field, located between Upper Ross Lake and Redout Lake, 75 km northeast of Yellowknife and 3.5 km east of the Redout granite, Canada (62°44′37″N, 113°6′26″W). Beusite-(Ca) occurs in a beusite–triphylite nodule ~6 × 5 × 3 cm. Graftonite-(Mn) and graftonite-(Ca) were found in phosphate nodules of two pegmatites at Lutomia and Michałkowa villages, respectively, in the Góry Sowie gneissic block, Lower Silesia, southwest Poland. This block is a product of multistage evolution culminated ~385–370 Ma by amphibolite-facies metamorphism and migmatization at temperatures of 775–910 °C and pressures of 6.5–8.5 kbar. The origin of the pegmatites thought to be related to anatectic melts, generated by partial melting of the metasedimentary–metavolcanics sequence. Phosphate nodules reaching 5 × 3 × 3 cm are sitting in blocky feldspar zones (with massive albite, some plagioclase, muscovite, and schorl-foitite tourmaline) and contain a large number of other phosphates e.g. monazite-(Ce), xenotime-(Y), graftonite-(Mn), graftonite-(Ca), beusite-(Ca), sarcopside, triphylite partly oxidized topotactically to ferrisicklerite and heterosite, wolfeite, triploidite, staněkite, hagendorfite, ferrohagendorfite, alluaudite, fluor- and hydroxylapatite, whitlockite, kryzhanovskite, phosphoferrite, ludlamite, vivianite, fairfield-ite, hureaulite, earlshannonite, whitmoreite, strunzite, ferrostrunzite, beraunite, dufrénite, landesite, jahnsite-(CaMnFe), -(CaMnMn), and -(MnMnMn), and occasionally also malhmoodite and zigrasite. Fergusonite-(Y), gadolinite-(Y), allanite-(Ce), ilmenite, titanite, sillimanite, uraninite, pyrite, arsenopyrite, löllingite, chalcopyrite, Cd-wurtzite or sphalerite, chalcocite or covellite, cuprite, native copper, goethite, and unidentified Mn oxides were found as tiny inclusions in the phosphates or in the rock-forming minerals. Thus graftonite-(Mn), graftonite-(Ca), and beusite-(Ca) are common primary phosphates in phosphate nodules, occurring as lamellar intergrowths with sarcopside ± triphylite/lithiophilite, products of exsolution from a (Li,Ca)-rich graftonite-like parent phase crystallized at high temperature from P-bearing hydrosaline melts. Beusite-(Ca) forms pale-brown lamellae 0.1–1.5 mm wide, epitaxially intergrown with triphylite. Pinkish brown graftonite-(Mn) and more brownish graftonite-(Ca) occur as lamellar intergrowths up to 0.5 mm wide with triphylite or products of its topotactic oxidation. All three minerals are transparent have a vitreous luster, a good cleavage on {010} [for beusite-(Ca) it is also observed on {100}], no parting and irregular fracture. They are brittle with a Mohs hardness of ~5 and both are non-fluorescent. The densities were not measured; Dcalc = 3.610, 3.793, and 3.592 g/cm3 for beusite-(Ca), graftonite-(Mn), and graftonite-(Ca) respectively. In transmitted light the minerals are colorless, non-pleochroic. They are optically biaxial (+), with α = 1.685 (2), 1.710(2), 1.690(2), β = 1.688(2), 1.713(2), 1.692(2), and γ = 1.700 (5), 1.725(2), 1.710(5); 2Vmeas = 46.0(5), 54(2), and 40.1(6)° (λ = 589 nm), respectively, for beusite-(Ca), graftonite-(Mn), and graftonite-(Ca). Respectively the optical orientations are: X || b; Yâ = 40.3° in β obtuse (the dispersion of an optical axes is r < v, weak); Zâ = 49.7° in β acute; X || b, Y ^ a = 44.2° (in β obtuse), Z ^ c = 35.0° (in β acute); X || b, Y ^ a = 41.4° in β acute and Z ^ c = 32.1° in β acute. The Raman spectrum of beusite-(Ca)/graftonite-(Mn)/graftonite-(Ca), in the range 100–1200 cm–1, shows the peaks at (cm–1; s – strong, m – medium, w – weak, vw – very weak): 961s/ 966s/ 968s, 1008s/ –/ 1013s, 1027s/ 1025m/ 1032s, 1054w/ –/ –, 1090m/ –/ 1098m, 1104m/ 1117w / 1106m (stretching vibrations of the PO4 groups); 592vw/ 587/ 590, 562m/ 566/ –, 548w/ –/ –, 473vw/ –/ 472, 458w/ 451/ 458, 416w/ 423/ – (bending vibrations of PO4 and stretching vibrations of CaO8 and MnO6 polyhedra). The peaks 347vw, 261w, 231vw, 212w, 182vw, 160vw, 140vw, and 115vw for beusite-(Ca) as well as multiple weaker peaks below 400 cm–1 for graftonite-(Mn) and graftonite-(Ca) are assigned to an angular deformation of the CaO8 and MnO6 polyhedra. The averages of ten WDS electron probe analyses for beusite-(Ca)/ 20 spots for graftonite-(Mn)/ 2 spots for graftonite-(Ca) [wt%, (range)] are: P2O5 41.63 (41.00–42.10)/ 40.02 (39.62–40.46)/ 41.52 (41.36–41.68), FeO 19.43 (19.00–19.80)/ 27.31 (26.07–28.83)/ 29.13 (27.81–30.44), MnO 23.63 (23.10–25.10)/ 26.06 (25.61–26.46)/ 12.14 (11.34–12.94), MgO nd/ 0.66 (0.57–0.74)/ 0.56 (0.09–1.03), CaO 15.45 (14.30–16.10)/ 4.74 (3.74–5.97)/ 16.17 (16.05–16.28), Zn bdl/ 0.29 (0.20–0.36)/ bdl, total 100.14/ 99.09/ 99.51. The empirical formulae based on 8O pfu are: respectively M(1)(Ca0.94Mn0.06)M(2),M(3)(Mn1.08Fe0.92)Σ3.00P2.00O8/M(1)(Mn0.70Ca0.30)M(2),M(3)(Fe1.34Mn0.60Mg0.06Zn0.01)Σ3.01P1.99O8/ M(1)(Ca0.98Mn0.02) M(2),M(3)(Fe1.38Mn0.56Mg0.05)Σ2.99P2.00O8. The Mössbauer spectra show that in beusite-(Ca) 86% of Fe2+ occurs at the M(2) site and 14% at the M(3) site while for graftonite-(Mn) Fe is completely disordered over the M(2) and M(3) sites, which leads to the structural formula M1(Mn0.70Ca0.30)

M2(Fe0.67Mn0.27Mg0.06Zn0.01)M3(Fe0.67Mn0.33)(PO4)2. No Mössbauer data was obtained for graftonite-(Ca). No X-ray powder data were obtained since all minerals are intimately intergrown with triphylite. The strongest lines of the calculated powder Xray diffraction patterns on the basis of single-crystal data are [d Å (I; hkl)]: 3.564 (97; 130), 3.030 (58; 102), 2.991 (76; 131), 2.932 (87; 040,112), 2.904, (100; 230), 2.873 (86; 221), 2.718 (86; 311), 2.413 (37; 311) for beusite-(Ca); 3.506 (73; 130), 3.016 (35; 102), 2.952 (55; 131), 2.916 (53; 112), 2.899 (44; 300), 2.874 (100; 230,040), 2.858 (79; 221), 2.717 (79; 311) for graftonite-(Mn) and 3.654 (100; 130), 3.133 (56; 102), 3.097 (57; 131), 3.042 (76; 040,112), 3.014, (77; 230), 2.979 (85; 221), 2.834 (68; 311), 2.542 (30; 311) for graftonite-(Ca). The crystal structures of beusite-(Ca), graftonite-(Mn) and graftonite-(Ca). were refined to R1 = 1.55, 2.34, and 1.63%, respectively, for 1832, 1911, and 1793 Fo>4σF reflections. All these species are isostructural with graftonite, M(1)FeM(2),M(3)Fe2(PO4)2 (monoclinic system; space group P21/c, Z = 4). The unit-cell parameters, respectively, are a = 8.799(2)/ 8.811(2)/ 8.792(2), b = 11.724(2)/ 11.494(2)/ 11.743(2), c = 6.170(1)/ 6.138(1)/ 6.169(1) Å, β = 99.23(3)°/ 99.23(3)°/ 99.35(3)°; V = 628.3/ 613.5/ 628.5 Å 3. Chemistry and crystal-structure refinement indicate that the M(1) site is occupied dominantly by Mn in graftonite-(Mn) and by Ca in graftonite-(Ca) and beusite-(Ca). In the last, one Mn2+ is strongly ordered at the [6]-coordinated M(3) site, with its minor amount at M(1). However ordering of Mn2+ and Fe2+ over the M(2) and M(3) sites is not part of the classification criteria for this group. In graftonite-(Mn) and -(Ca) the M(2) and M(3) sites are occupied by Fe2+ and Mn2+, with Fe2+ dominant over Mn2+ at the aggregate M(2)+M(3) sites. The mineral names are given according current classification of the graftonite-group (Hawthorne and Pieczka 2018). Both minerals are common primary phosphates in phosphate nodules, occurring as lamellar intergrowths with sarcopside ± triphylite/ lithiophilite, products of exsolution from a (Li,Ca)-rich graftonite-like parent phase crystallized at high temperature from P-bearing hydrosaline melts. The holotype of beusite-(Ca) is deposited in the Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, D.C., U.S.A. The holotype and cotype specimens of graftonite-(Mn) and graftonite-(Ca) are deposited in the Mineralogical Museum of University of Wrocław, Poland). Holotype of graftonte-(Ca) is also holotype for maneckiite. D.B.

References cited

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Hyršlite*

F.N. Keutsch, D. Topa, and E. Makovicky (2018) Hyršlite, Pb8As10Sb6S32, a new N = 3;3 member of the sartorite homologous series from the Uchucchacua polymetallic deposit, Peru. European Journal of Mineralogy, 30(6), 1155–1162.

Hyršlite (IMA 2016-097), Pb8As10Sb6S32, monoclinic, is a new member of the sartorite homologous series of Pb–(As,Sb) sulfosalts. It was discovered at the Socorro section the Uchucchacua polymetallic deposit, Oyon district, Catajambo, Lima Department, Peru. It is an Ag–Mn–Pb–Zn vein, replacement and skarn mineral deposit, hosted by limestones and surrounded by andesitic and dacitic volcanic intrusions of Late Oligocene age (~25 Ma) with which the formation of the deposit might be connected. Ores occurs as fissure infill and replacement of adjacent limestone in a succession of antiforms and synforms. In the first stage, silicates of Mn, Fe, and Ca (rhodonite, bustamite, etc.) were deposited. In Stage 2, friedelite, magnetite, Fe-sphalerite, Mn-wurtzite, alabandine, and pyrrhotite were deposited. Main gangue minerals were calcite, kutnohorite, rhodochrosite, and quartz. In the late Stage 3, Ag, As, and Sb sulfosalts were introduced and Fe-poor sphalerite and alabandite coexist with calcite and pyrite. Orpiment, marcasite and siderite along with Mn oxides, goethite and cerussite ascribed to a supergene stage. This deposit for a few decades was a source of a number of new minerals including benavidesite Pb4(Mn,Fe)Sb6S14, uchucchacuaite AgMnPb3Sb5S12, menchettiite AgPb2.40Mn1.60Sb3As2S12, manganoquadratite AgMnAsS3, keutschite Cu2AgAsS4, agmantinite Ag2MnSnS4, and spryite Ag8(As3+,As5+)S6, and now hyršlite found in close association with orpiment, stibnite, quartz, tennantite/tetrahedrite, manganoquadratite and Pb–Ag–Mn–Sb–As–S sulfosalts, including menchettiite in a calcite matrix. Hyršlite forms very rare individual crystals up to ~300 µm, and euhedral to anhedral grains intergrown with manganoquadratite and Pb–Ag–Mn–Sb–As–S sulfosalts. The mineral is gray, opaque with metallic luster. It is brittle, without observable cleavage or parting. Indentation microhardness VHN25 = 215 (202–221) kg/mm2 corresponding to 4 of Mohs scale. Density was not measured because of paucity of available material; Dcalc = 5.26 g/cm3 based on simplified chemical formula. In reflected light, hyršlite is grayish-white, with red internal reflections on thin edges or at grain boundaries. Pleochroism was not detected, bireflectance is moderate. Anisotropism is distinct in dark gray-to-creamy rotation tints. The reflectance values in air [Rmax/Rmin (nm)] (COM wavelengths are bolded) are: 39.0/33.6 (400), 38.8/32.3 (420), 38.9/32.6 (440), 39.1/32.6 (460), 39.0/32.6 (470), 39.0/32.4 (480), 39.1/32.6 (500), 38.9/32.4 (520), 38.6/32.2 (540), 38.5/32.1 (546), 38.3/31.8 (560), 38.1/31.8 (580), 37.9/31.5 (589), 37.8/31.4 (600), 37.4/31.2 (620), 37.0/30.9 (640), 36.7/30.7 (650), 36.3/30.6 (660), 35.7/30.0 (680), 35.5/29.7 (700). At short wavelengths, the reflectance values are lower compare to hepta- to hendekasartorites; decrease in the R values towards the long wavelengths is more moderate than for the “sartorite” species. The average of 11 WDS electron probe analyses on 3 grains [wt%, (range)] is: Pb 39.26 (38.72–39.71), Sb 17.47 (16.55–18.41), As 17.97 (17.28–18.46), S 24.60 (24.40–24.75); total 99.30. No other elements were detected. The empirical formula based on 56 apfu (24 Me + 32 S) is Pb7.92Sb6.00As10.02S32.06 (ƩMe

= 23.94) or (based on 32 S apfu) Pb7.90Sb5.98As10.00S32Me = 23.89) or (based on 24 Me apfu) Pb7.94Sb6.01As10.05S32.15. Compositionally hyršlite lies between guettardite and twinnite on the one hand, and hendekasartorite on the other hand. Powder X-ray data were not collected. The strongest lines of the calculated powder X-ray diffraction pattern are [dcalc Å (Icalc%; hkl)]: 3.880 (59; 021), 3.512 (100; 015), 3.493 (46; 211), 3.488 (47; 213), 2.974 (45; 213), 2.968 (47; 215), 2,776 (71; 221), 2.773 (70; 223). The parameters of the monoclinic unit cell of hyršlite refined from single-crystal data are: a = 8.475(3), b = 7.917(3), c = 20.039(8) Å, β = 102.070(6)°, V = 1314.8 Å3; space group P21, Z = 2. The crystal structure of hyršlite was solved by direct methods to R1 = 0.0728 for 2862 Fo>4σ(Fo) reflections. The structure contains 12 independent cation and 16 distinct S sites. There are four fully occupied Pb tricapped trigonal prismatic sites (combined into zig-zagging “walls” which separate As–Sb based slabs of the structure), two fully occupied As sites, one Sb site and five mixed (As,Sb) sites. In projection parallel to the a axis, the crystal structure is a typical member of the sartorite homologous series, a sartorite homologue N = 3;3, and homeotype of twinnite and guettardite. The surfaces of the tightly bonded double-layer in the (As,Sb)-rich slabs have different cation configurations—one resembles coordinations observed in guettardite but the opposite one, with (As,Sb) cation pairs and single polyhedra, appears unique among sartorite homologues. The unique variation of structural motif built by covalent bonds of As and Sb, bond configuration and polyhedron aggregation show that it is not just a composition point in a solid solution series, but independent mineral species. The mineral name honors Jaroslav Hyršl, Czech mineralogist and expert on Peruvian minerals, in particular on the Uchucchacua deposit. The holotype is deposited in the reference collection of the Naturhistorisches Museum Wien, Austria. D.B.

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Magnesiobeltrandoite-2N3S*

F. Cámara, R. Cossio, D. Regis, V. Cerantola, M.E. Ciriotti, and R. Compagnoni (2018) Beltrandoite, a new root-name in the högbomite supergroup: the Mg end-member magnesiobeltrandoite-2N3S. European Journal of Mineralogy, 30(3), 545–558.

Magnesiobeltrandoite-2N3S (IMA 2016-073), ideally Mg6Al20Fe23+O38(OH)2, trigonal, is a new member of the högbomite supergroup. It was found in a metamorphosed layered mafic complex along the stream “Marmore” of the middle Valtournenche, Aosta Valley, Italy (~N 45°49′36″; E 7°34′51″) in the debris underneath the Etirol-Levaz slice (a lens-like continental fragment, sandwiched between the overlying blueschist- to greenschist-facies Combin zone and the underlying eclogitefacies Zermatt-Saas zone). The slice consists of pre-Alpine, most likely Variscan, amphibolite- to granulite-facies gneisses, micaschists and metabasics which were overprinted by Alpine eclogite-facies metamorphism with PT condition of formation thought to be ~560 °C and pressure up to ~24 kbar. The specimen containing magnesiobeltrandoite-2N3S was derived from a lens-like body of a layered metagabbro where it occurs as massive chloritite bands, most likely after primary spinel pyroxenites. The mineral occurs in a fine-grained chlorite matrix locally containing centimeter to decimeter long darker boudins with relict green spinel, cut by corundum + chlorite ± dolomite veins. Locally, Cr-rich magnetite, Mn-ilmenite and pyrite are observed in the matrix and in alteration rims of relict phases (in particular magnesiobeltrandoite-2N3S). Magnesiobeltrandoite-2N3S forms subhedral to euhedral black (dark reddish-brown in thin section) grains (~50–400 µm), moderately elongated parallel to c axis. Grains are in direct contacts with clinochlore and dolomite or included in green spinel relics with core compositions ~Sp59Hc41 up to Sp42Hc58 in the rim of small grains or even Sp30Hc70. The Cr-rich spinel close to the corundum veins is more hercynite rich (Sp20Hc80) and contains also trace amounts of V. Large grains of hercynitic spinel are fractured and cracks are filled by dolomite and diaspore. Chlorites of the matrix show sharp zonation with enrichment of Fe and depletion of Si at the rims corresponding to Fe-bearing aluminous clinochlore “corundophilite”. Magnesiobeltrandoite-2N3S shows limited zonation with slighter Ti-richer cores but never reaching högbomitic compositions. Most of the magnesiobeltrandoite-2N3S grains show incipient alteration to clinochlore even richer in Fe and Al than the rims of crystals in the matrix. Magnesiobeltrandoite-2N3S has dark brown streak and a vitreous luster. It is brittle, with uneven fracture and no cleavage observed. Mohs hardness is ~6–6½. Density was not measured due to small grain size and the presence of chlorite and magnesite inclusions; Dcalc = 3.93 g/cm3. No fluorescence under UV radiation and no cathodoluminescence was observed. No reactions with HCl, HNO3, and H2SO4 were observed. The mineral is weakly pleochroic with E (deep reddish brown) (along c axis) > O (reddish brown). It is optically uniaxial (–). The calculated mean refractive index is ~1.80. The Raman spectra collected with polarization perpendicular to the length of the crystal and along it shows significant difference in intensities and slight shifts in peak positions. The strongest bands are observed (cm–1) at 854, 717, 506, and 264. Minor bands present at 812, 657, 419, 371, and 109. A weak and polarized band centered at 3364 cm–1 corresponds to an O–H bond parallel to c axis. The differences compare to Raman spectra of magnesiohögbomite-2N4S (Shimura et al. 2012) for, and the “Ti-free högbomite” of Tsunogae and Santosh (2005) are discussed. The Synchrotron Mössbauer spectrum (with the beam focused to a spot size of ~15 × 15 µm) was collected from a single crystal previously checked using X-ray single-crystal diffraction to exclude the presence of different species inclusions. The refined Fe3+/Fetotal ratio 46(2)% is in good agreement with observed values for Fe2+ and Fe3+ in these coordination environments. The average of WDS electron probe analysis (55 data points) is [wt% (range)]: MgO 10.43 (9.33–11.11), ZnO 0.34 (0.14–0.52), NiO 0.09 (0–0.16), MnO 0.23 (0.15–0.32), FeO 11.80 (10.83–14.18), Fe2O3 10.83 (9.66–12.13) [by charge balance and 28 cations pfu], Al2O3 61.10 (59.41–63.50), Cr2O3 1.98 (1.23–3.19), V2O3 0.15 (0.09–0.25), TiO2 2.91 (1.14–4.49), H2O 1.18 (1.16–1.19) [by stoichiometry considering 2 OH pfu], total 100.90. Sn, Si, P, Ni, Ca, Na, and K were below detection limits. The empirical formula based on 28 cations and 40 (38 O and 2 OH) anions pfu is [Al18.36Mg3.96Fe2.522+Fe2.083+Ti0.56Cr0.40Zn0.06V0.033+Mn0.02]Σ28O38(OH)2. The stron gest lines in the X-ray powder diffraction pattern are [d Å (I; hkl)]: 2.858 (42; 110), 2.735 (51; 107), 2.484 (46; 018), 2.427 (100; 115), 1.568 (29; 128), 1.514 (30; 0.2.12), 1.438 (42; 2.0.13), 1.429 (72; 220). The cell parameters refined from powder data are a = 5.7164(1), c = 22.9702(8) Å, V = 650.03 Å3. Single-crystal X-ray studies on a crystal of 0.080 × 0.060 × 0.020 mm show the mineral is trigonal, space group P3m1, a = 5.7226(3), c = 23.0231(9) Å, V = 652.95 Å3, Z = 1. The crystal structure of magnesiobeltrandoite-2N3S was refined to R1 = 0.0219 for 1626 I>2σ(I) unique reflections. Magnesiobeltrandoite-2N3S is isostructural with magnesiohögbomite-2N3S. There are 10 symmetrically independent cation sites (four tetrahedral and six octahedral) and 10 anion sites. Two sites with octahedral coordination (M3 and M5) and one site with tetrahedral coordination (T4) belong to the nolanite modules [composed by a T1-layer of tetrahedrally (T4) and octahedrally (M5) coordinated atoms and an O-layer built by octahedrally (M3) coordinated sites], while four sites with octahedral coordination (M1, M6, M8, and M10) and three sites with tetrahedral coordination (T2, T7, and T9) correspond to spinel modules [composed by T2-layers of tetrahedrally (T2, T7, and T9) and octahedrally (M1 and M8) coordinated atoms and an O-layer built by octahedrally (M1 and M10) coordinated sites]. The assigned composition of M5 site is (Fe0.473+Ti0.28Fe0.172+Mg0.07) thus Fe3+ is dominantly ordered in nolanite module (0.94 apfu), while some Fe3+ is present in the sites with tetrahedral coordination (T4) of the nolanite module (0.16 apfu) and in the T7 and T9 sites of the T1-layer of the spinel modules (0.12 apfu each site), as well as in octahedral sites of the spinel modules (up to 0.74 apfu). Fe3+ is dominant at only one of octahedral sites (M5) of the nolanite module, while Al is dominant at the M3 site and in the nolanite module in a whole. The dominance of Fe3+ at M5 site where Ti and Sn are located in högbomite and nigerite, respectively, can be obtained through two charge-balanced substitutions: M5Ti4+ + T4R2+(Fe,Mg,Zn) > M5Fe3+ + T4R3+(Fe,Al,Cr) or M5Ti4+ + T4R3+(Fe,Al,Cr) + O4(O)2– > M5Fe3+ + T4R3+(Fe,Al,Cr) + O4(OH). The first one has been chosen for formula calculation. Magnesiobeltrandoite-2N3S, is a new member of the högbomite supergroup [N × TM4O7(OH) × S × T2M4O8] (Mills et al. 2009) and the first “nolanitic” Fe3+-dominant member (thus can be considered as a parent species of a new “beltrandoite” mineral group). This magnesiobeltrandoite-2N3S is very rich in Fe2+ (Mg > Fe2+ only for 0.10 apfu) being close to a potential new mineral “ferrobeltrandoite-2N3S”. The name is given according the rules of the högbomite supergroup nomenclature (Armbruster 2002) approved by CNMNC IMA. The proposed root-name beltrandoite honors Marco Beltrando (1978–2015), geologist and petrologist at the Department of Earth Sciences of the University of Torino, for his contributions to the evolution of the Alpine orogeny. The prefix is according the dominance of Mg in spinel modules and the suffix is according the polysomatic sequence of nolanite and spinel modules. The holotype material (a thin section and a 2 mm thick rock chip) is deposited in the Museo Regionale di Scienze Naturali di Torino, Italy. D.B.

Comment:

Another Fe3+-dominant member of högbomite supergroup zincovelesite-6N6S was later approved by CNMNC IMA (see abstract below and comment to that).

Zincovelesite-6N6S*

N.V. Chukanov, M.G. Krzhizhanovskaya, S. Jančev, I.V. Pekov, D.A. Varlamov, J. Gӧttlicher, V.S. Rusakov, Y.S. Polekhovsky, A.D. Chervonnyi, and V.N. Ermolaeva (2018) Zincovelesite-6N6S, Zn3(Fe3+,Mn3+,Al,Ti)8O15(OH), a new hӧgbomite-supergroup mineral from Jacupica mountains, Republic of Macedonia. Mineralogy and Petrology, 112(5), 733–742.

Zincovelesite-6N6S (IMA 2017-034), Zn3(Fe3+,Mn3+,Al,Ti)8O15(OH), trigonal, was discovered in the orogenetic zone related to the “Mixed Series” metamorphic complex near the Nežilovo village (4.5 rm NW) and about 25 km WSW of the city of Veles, Jacupica Mountains, Pelagonia mountain range, Republic of Macedonia (41°41′ N, 21°25′ E). Metamorphosed volcano-sedimentary formation composed mainly of albite augen gneisses and meta-rhyolites with lenses of dolomitic marbles metasomatically replaced by a very unusual and complex mineral assemblages. A specific feature of these metasomatic rocks is their formation under highly oxidizing conditions. As a result, the chalcophile elements (S, As, Sb, Zn, and Pb) are mainly concentrated in the form of oxides and oxysalts, while sulfides and sulfosalts are present only in trace amounts. In metasomatic rocks of the Nežilovo area, hӧgbomite-supergroup minerals occur in predominantly oxide and predominantly silicate-baryte associations. In oxide rocks only zincovelesite-6N6S was found. In rocks containing baryte, Zn-rich amphiboles and micas as the major components, both Fe3+- and Al-dominant hӧgbomite-supergroup minerals occur (including zincovelesite-6N6S, zincohӧgbomite-6N6S, and its Sb5+- and Mn4+-analogues). Relics of zircon and zincochromite belong to the earliest paragenesis. Thereafter franklinite and hetaerolite crystallized. During the next stage, franklinite and hetaerolite were partly replaced by gahnite to form predominantly franklinite–hetaerolite–gahnite aggregate. Zincovelesite-6N6S crystallized at a relatively late stage of metasomatic processes and probably has a hydrothermal origin. Ferricoronadite is one of the latest minerals in this association. Other associated minerals include As-rich fluorapatite, dolomite, Zn-bearing talc, almeidaite, hydroxycalcioroméite, zircon, quartz, and scheelite. In oxide zones zincovelesite-6N6S forms lenticular aggregates up to 2 × 2 × 0.5 mm consisting of thin near-coplanar platelets up to 70 × 70 × 1 μm while in silicate-baryte zones it forms oriented pseudomorphs after gahnite and epitaxial (with parallel c axes) intergrowths with nežilovite up to 0.5 × 0.5 × 0.1 mm in size. Zincovelesite-6N6S is black, opaque and has a brownish-black streak and strong submetallic to metallic luster. It is brittle. The micro-indentation hardness VHN200 = 1118 (946–1233) kg/mm2 corresponding to ~6½ of the Mohs scale. The density was not measured due to a very small crystal size; Dcalc = 5.158 g/cm3. In reflected light zincovelesite-6N6S is light gray with no internal reflections observed. It is anisotropic and bireflectant. The reflectance values were measured in air between 400 and 700 nm with a 20 nm interval. The values for the COM wavelengths are [Rmin, Rmax (%), (nm)]: 13.4, 17.1 (470), 12.8, 16.5 (546), 12.6, 16.2 (589), 12.2–15.6 (650). The infrared spectrum of zincovelesite-6N6S has bands at (cm–1): 3407 and 817 (O-H stretching and M···O-H bending vibrations, respectively); strong bands in the range 360-650 (M···O-stretching vibrations where M = Fe3+, Mn3+, Al, Ti). The average of 15 WDS electron probe analyses [wt%, (range)] is: MgO 0.97 (0.34–1.36), CuO 0.50 (0.27–0.72), ZnO 30.80 (27.86–33.79), Al2O3 8.17 (7.23–8.69), Mn2O3 21.31 (19.72–24.05), Fe2O3 29.44 (26.97–33.44), TiO2 5.28 (3.07–7.97), Sb2O5 3.74 (1.24–6.52), H2O 1.1(2) (by gas chromatography of products of ignition at 1200 °C), total 101.31. Based on Mössbauer spectroscopy and Mn and Fe K-edge XANES spectroscopy, all Fe and at least most part of Mn are trivalent but substantial portion of Mn may be tetravalent. The empirical formula based on 16 O pfu is H1.05(Zn3.26Mg0.21Cu0.05Fe3+3.18Mn3+2.32Al1.38Ti0.57Sb0.20)Σ11.17O16. The strongest lines of the powder X-ray diffraction pattern are [d Å (I%; hkl)]: 2.952 (62; 110); 2.881 (61; 1.0.16); 2.515 (100; 204); 2.493 (88; 1.1.12); 2.451 (39; 1.0.20); 1.690 (19; 304,2.1.16); 1.572 (19; 2.0.28); 1.475 (29; 221). Single-crystal X-ray diffraction study could not be performed because aggregates of zincovelesite-6N6S are compact and consist of thin near-coplanar platelets up to 1 μm thick. The powder diffraction study showed that the new mineral is trigonal, probable space group is P3m1, a = 5.902(2), c = 55.86(1) Å, V = 1684.8 Å3, and Z = 6. Zincovelesite-6N6S is isostructural with högbomite-supergroup minerals. Zincovelesite-6N6S is the first Fe3+- dominant member of the högbomite supergroup and, can be considered as a parent species of a new mineral group (see comment below) with Ti4+ as the major charge-compensating high-valent cation and Fe3+ as the major trivalent cation. The rootname velesite is given for the discovery locality near the city of Veles. Fragments of the holotype specimen are deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia, and in the National Institution Macedonian Museum of Natural History, Skopje, Macedonia. Yu.U.

Discussion:

The authors claim that this is the first Fe3+-dominant member of the högbomite supergroup. Actually, the first one was magnesiobeltrandoite-2N3S, IMA No. 2016-073 (see the abstract above), ideally Mg6Al20Fe23+O38(OH)2, approved by CNMNC IMA about a year before zincovelesite-6N6S (Cámara et al. 2016 not cited by the authors, and Cámara et al. 2018, the later probably published after the acceptance of their paper). In magnesiobeltrandoite-2N3S, Fe3+ is dominant over Ti in the nolanite module. According the classification of högbomite-supergroup approved by CNMNC IMA (Armbruster 2002) and the suggestions of Shiumura et al. (2012), “…högbomite-group minerals are defined as Ti > Sn. The corresponding Ti-free samples should be classified into a newly defined group in close relation with högbomite and nigerite groups.” Thus, the mineral deserved a new root-name, and it was chosen—beltrandoite. This classification also assigns a subgroup prefix to the root-name on the basis of the aluminium spinel module: ‘zinco’, ‘ferro’, or ‘magnesio’ depend on domination of gahnite, hercynite or spinel components respectively. “A corresponding choice of prefixes is required if högbomite minerals with other spinel modules are discovered” (Armbruster 2002). Unfortunately, no structure determination has been provided in the zincovelesite-6N6S description and it is not possible to discuss about the site partitioning between the two types of modules. It is reported that the Fe K XANES spectrum of zincovelesite-6N6S is very close to that of the spinel-type ferrite franklinite ZnFe2O4. Because, Al is > 1.5 apfu and (Fe3+ + Mn3+ = 5.5 apfu), Fe3+ and Mn3+ might be dominant cations in the octahedral sites of both spinel and nolanite modules. Yet, the classification by Ambruster (2002) did not foresee Al-poor spinel modules. The mineral clearly deserved a new name, but not a root-name following the classification in force at the time of the approval. It is rather confusing that IMA-CNMNC accepted the proposal of a new root-name based on a criterion used in another new mineral approved by the commission just few months before. It turns out evident that a new classification scheme was necessary for this group of minerals considering the new data presented by the team proposing zincovelesite-6N6S. At the present state of the art, to avoid any further confusion, any further member of this group should wait until an upgraded nomenclature of this supergroup is presented and approved my IMA-CNMNC. F.C.

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