NIOBOHEFTETJERNITE, ScNbO4, A NEW MINERAL FROM THE BEFANAMO PEGMATITE, MADAGASCAR

ABSTRACT A new mineral, nioboheftetjernite, ideally ScNbO4, was found in the Befanamo pegmatite, Analamanga, Madagascar. It occurs as anhedral grains and very crude elongated crystals up to 200 μm in length in an intergrowth with rossovskyite, ilmenite, rutile, thortveitite, euxenite-(Y), feldspar, and quartz. The mineral is black with dark-brown to black streak and submetallic luster. It has no cleavage and its fracture is uneven. Dcalc is 5.855 g/cm3. The Raman spectrum and reflectance data are reported. The chemical composition (wt.%) is MgO 0.06, MnO 2.49, Fe2O3 12.14, Sc2O3 11.34, TiO2 5.94, SnO2 1.45, Nb2O5 32.23, Ta2O5 29.93, WO3 3.38, total 98.96. The empirical formula calculated on the basis of 4 O apfu is (Sc0.40Fe3+0.37Ti0.15Mn2+0.08)Σ1.00(Nb0.58Ta0.33W0.03Ti0.03Sn0.02)Σ0.99O4. The simplified general formula is (Sc,Fe3+)(Nb,Ta)O4. Nioboheftetjernite is monoclinic, P2/c, a = 4.7092(3), b = 5.6531(4), c = 5.0530(4) Å, β = 90.453(3)°, and V = 134.515(17) Å3. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 4.722(22)(100), 3.776(22)(011), 3.628(44)(110), , 2.938(83)(111), 2.472(30)(021), and . The crystal structure, refined from single-crystal X-ray diffraction data (R1 = 0.016), is of the “wolframite” type. The mineral is named as the Nb-analogue of heftetjernite, ScTaO4.

Luboržákite, Mn2AsSbS5, a new member of pavonite homologous series from Vorontsovskoe gold deposit, Northern Urals, Russia

Luboržákite, ideally Mn2AsSbS5, is a new mineral from the Vorontsovskoe gold deposit, Northern Urals, Russia. It forms long-prismatic crystals up to 70 × 20 μm and anhedral grains of the same size embedded in the matrix of Mn-bearing dolomite and Mn-bearing calcite. Associated minerals include pyrite, orpiment, realgar, stibnite, aktashite, alabandite, boscardinite, chabournéite, coloradoite, clerite, écrinsite, gold, routhierite, sphalerite and twinnite. Luboržákite is black, opaque with metallic lustre and has a black streak. It is brittle and has an uneven fracture. No cleavage and parting have been observed. Mohs hardness is 4–4½. Dcalc = 4.181 g cm–3. In reflected light, luboržákite is tin-white, weakly anisotropic with rotation tints varying from dark grey to grey. The chemical composition of luboržákite is (wt.%; electron microprobe, WDS mode): Mn 21.23, Cu 0.29, Ag 0.56, Pb 1.90, As 15.25, Sb 27.03, S 33.23, total 99.49. The empirical formula based on the sum of all atoms = 9 apfu is Mn1.86Pb0.04Ag0.03Cu0.02As0.98Sb1.07S5.00. The new mineral is monoclinic, space group C2/m with a = 12.5077(6), b = 3.8034(2), c = 16.0517(8) Å, β = 94.190(4)°, V = 761.57(6) Å3 and Z = 4. The crystal structure of luboržákite was solved from the single-crystal X-ray diffraction data to R = 0.0383 for 712 observed reflections with I > 3σ(I). Luboržákite is a new member of the heterochemical isostructural series of ‘unit-cell twinned’ structures, named the pavonite series. The new mineral honours Lubor Žák, a prominent Czech crystallographer and the professor of the Charles University in Prague, Czech Republic.

Nickeltyrrellite, CuNi2Se4, a new member of the spinel supergroup from El DragÓn, Bolivia

Nickeltyrrellite, ideally CuNi2Se4, is a new selenide species from the El Dragón mine, Department of Potosí, Bolivia. It most frequently occurs as anhedral to subhedral grains (up to 20 μm in size) in association with cerromojonite, klockmannite, clausthalite, and penroseite, forming fracture fillings in pre-existing krut'aite−penroseite solid solutions. Nickeltyrrellite is non-fluorescent, black, and opaque with a metallic luster and black streak. It is brittle, with an irregular fracture and no obvious cleavage and parting. In plane-polarized incident light, nickeltyrrellite is cream to pale pinkish, displaying no internal reflections. Between crossed polarizers, it is isotropic. The reflectance values in air for the COM standard wavelengths are 45.9 (470 nm), 47.6 (546 nm), 48.1 (589 nm), and 49.8 (650 nm). Electron-microprobe spot analyses (n = 28) of the grain populations used for the EBSD study yielded a mean composition of Cu 13.01, Fe 0.27, Co 6.66, Ni 16.98, S 1.04, Se 61.91, total 99.87 wt.%. The empirical formula, normalized to 7 apfu, is Cu1.00(Ni1.42Co0.56Fe0.02)Σ2.00(Se3.84S0.16)Σ4.00. The ideal formula is CuNi2Se4, which requires (in wt.%) Cu 12.79, Ni 23.63, Se 63.58, total 100. EBSD patterns reveal nickeltyrrellite as cubic, space group , with a = 9.99 Å, V = 997.0 Å3, Z = 8. The calculated density is 7.36 g cm−3. It formed in response to alteration of quijarroite + hansblockite + watkinsonite + clausthalite + penroseite aggregates by oxidizing, low-T, Cu-Ni-Co-Pb-bearing fluids at a fSe2/fS2 ratio greater than unity. Nickeltyrrellite is a new selenide belonging to the tyrrellite subgroup of the spinel supergroup. The new species has been approved by the IMA-CNMNC (2018-110) and is named for constituting the Ni-analogue of tyrrellite.

Comparative Taxonomy of Two Species of Acanthopagrus Peters, 1855 (Pisces: Sparidae) with the First Record of A. sheim Iwatsuki, 2013 from Iraq

Morphometric and meristic characteristics of two species of genus Acanthopagrus (A. arabicus and A. sheim) were described based on 19 specimens of A. arabicus and 10 specimens of A. sheim. Distinguished morphometric characteristics between two species are included; obvious black streak on anal fin in fresh specimens and the black spots on the membrane between spines of dorsal fin found in A. sheim only, while yellow lower lobe of caudal fin in A. arabicus in compared with black or dusky once in A. sheim. Pectoral, pelvic and anal fins being vivid yellow (yellow in A. sheim, anal fin with black streaks), caudal fin being yellow in the lower part, while grayish on the upper part of A. arabicus. The biometric characters of 33 out of 42 morphometric characters of A. arabicus were larger than that of A. sheim, which reported for the first time in Iraqi waters

Cerromojonite, CuPbBiSe3, from El Dragόn (Bolivia): A New Member of the Bournonite Group

Cerromojonite, ideally CuPbBiSe3, represents a new selenide from the El Dragόn mine, Department of Potosí, Bolivia. It either occurs as minute grains (up to 30 µm in size) in interstices of hansblockite/quijarroite intergrowths, forming an angular network-like intersertal texture, or as elongated, thin-tabular crystals (up to 200 μm long and 40 μm wide) within lath-shaped or acicular mineral aggregates (interpreted as pseudomorphs) up to 2 mm in length and 200 μm in width. It is non-fluorescent, black, and opaque, with a metallic luster and black streak. It is brittle, with an irregular fracture, and no obvious cleavage and parting. In plane-polarized incident light, cerromojonite is grey to cream-white, and weakly pleochroic, showing no internal reflections. Between crossed polarizers, cerromojonite is weakly anisotropic, with rotation tints in shades of brown and grey. Lamellar twinning on {110} is common. The reflectance values in air for the COM standard wavelengths (R1 and R2) are: 48.8 and 50.3 (470 nm), 48.2 and 51.8 (546 nm), 47.8 and 52.0 (589 nm), and 47.2 and 52.0 (650 nm). Electron-microprobe analyses yielded a mean composition of: Cu 7.91, Ag 2.35, Hg 7.42, Pb 16.39, Fe 0.04, Ni 0.02, Bi 32.61, Se 33.37, total 100.14 wt %. The empirical formula (based on 6 atoms pfu) is (Cu0.89Hg0.11)Σ = 1.00(Pb0.56Ag0.16Hg0.15 Bi0.11Fe0.01)Σ = 0.99Bi1.00Se3.01. The ideal formula is CuPbBiSe3. Cerromojonite is orthorhombic (space group Pn21m), with a = 8.202(1) Å, b = 8.741(1) Å, c = 8.029(1) Å, V = 575.7(1) Å3, Z = 4. Calculated density is 7.035 g·cm−3. The five strongest measured X-ray powder diffraction lines (d in Å (I/I0) (hkl)) are: 3.86 (25) (120), 2.783 (100) (122), 2.727 (55) (212), 2.608 (40) (310), and 1.999 (25) (004). Cerromojonite is a new member of the bournonite group, representing the Se-analogue of součekite, CuPbBi(S,Se)3. It is deposited from strongly oxidizing low-T hydrothermal fluids at a fSe2/fS2 ratio >1, both as primary and secondary phase. The new species has been approved by the IMA-CNMNC (2018-040) and is named for Cerro Mojon, the highest mountain peak closest to the El Dragón mine.

Lead-antimony sulfosalts from Tuscany (Italy). XVII. Meerschautite, (Ag,Cu)5.5Pb42.4(Sb,As)45.1S112O0.8, a new expanded derivative of owyheeite from the Pollone mine, Valdicastello Carducci: occurrence and crystal structure

The new mineral species meerschautite, ideally (Ag,Cu)5.5Pb42.4(Sb,As)45.1S112O0.8, has been discovered in the baryte + pyrite ± (Pb-Zn-Ag) deposit of the Pollone mine, near Valdicastello Carducci, Apuan Alps, Tuscany, Italy. It occurs as black prismatic crystals, striated along [100], up to 2 mm long and 0.5 mm thick, associated with baryte, boulangerite, pyrite, quartz and sphalerite. Meerschautite is opaque with a metallic lustre and shows a black streak. In reflected light, meerschautite is white in colour, weakly bireflectant and non pleochroic. With crossed polars, it is distinctly anisotropic with grey to dark grey rotation tints with brownish and greenish shades. Reflectance percentages for COM wavelengths [λ (nm), Rair (%)] are: 470: 39.7/41.4; 546: 38.3/39.9; 589: 37.4/39.0; 650: 35.8/37.2. Electron-microprobe data collected on two different samples gave (wt.%): Cu 0.22, Ag 3.15, Tl 0.07, Pb 48.54, Sb 25.41, As 2.82, S 19.74, Se 0.14, Cl 0.03, sum 100.12 (# 1) and Cu 0.22, Ag 3.04, Tl 0.13, Pb 48.53, Sb 25.40, As 2.93, Bi 0.06, S 19.82, Se 0.13, Cl 0.05, sum 100.31 (# 2). On the basis of 112 anions (S+Se+Cl) per formula unit, the empirical formulae are (Ag5.29Cu0.63)∑5.92(Pb42.43Tl0.06)∑42.49(Sb37.80As6.82)∑44.62(S111.53Se0.32Cl0.15)∑112 (# 1) and (Ag5.08Cu0.62)∑5.70(Pb42.22Tl0.12)∑42.34(Sb37.61As7.07Bi0.05)∑44.73(S111.45Se0.30Cl0.25)∑112 (# 2). Main diffraction lines, corresponding to multiple hkl indices, are [d in Å (relative visual intensity)]: 3.762 (m), 3.663 (s), 3.334 (vs), 3.244 (s), 3.016 (m), 2.968 (m), 2.902 (m), 2.072 (ms). The crystal structure study gave a monoclinic unit cell, space group P21, with a = 8.2393(1), b = 43.6015(13), c = 28.3688(8) Å, β = 94.128(2)°, V = 10164.93(2) Å3, Z = 2. The crystal structure has been solved and refined to a final R1 = 0.122 on the basis of 49,037 observed reflections. The structure is based on two building blocks, both formed by a complex column with a pseudotrigonal Pb6S12 core and two arms of unequal lengths (short and long arms, respectively). Two different kinds of short arms occur in meerschautite. One is an Ag-rich arm, whereas the other shows localized Sb–O–Sb bonds. Meerschautite is an expanded derivative of owyheeite and has quasi-homeotypic relationships with sterryite and parasterryite.

Weissite from Gambatesa mine, Val Graveglia, Liguria, Italy: occurrence, composition and determination of the crystal structure

Weissite, Cu2–xTe (x ≈ 0.21), a very rare copper telluride, occurs in a sample from the Gambatesa mine, Val Graveglia, Liguria, Italy, where it occurs as purplish black anhedral grains up to 0.1 mm in length and shows a black streak. No cleavage is observed and the Vickers hardness (VHN100) is 142 kg/mm2. Weissite is dark bluish black, weakly pleochroic, and moderately anisotropic in bluish tints. Reflectance percentages in air for Rmin and Rmax are 37.0, 38.4 (471.1 nm), 33.2, 34.2 (548.3 nm), 31.2, 32.1 (586.6 nm), and 28.6, 31.0 (652.3 nm), respectively.Weissite is trigonal and belongs to the space group P3m1 with the following unit-cell parameters: a = 8.3124(7) Å, c = 21.546(1) Å, V = 1289.3(2) Å3, and Z = 24. Electron microprobe analyses gave the chemical formula (Cu1.62Ag0.04Au0.04Fe0.04Sb0.04)Σ=1.78(Te0.96S0.02Se0.02). The crystal structure has been solved and refined to R = 1.95%. It consists of Cu and Te polyhedra forming complex crystal-chemical environments as is typical of many intermetallic compounds. The exceedingly short bond distances observed among the metals are discussed in relation to other copper tellurides and pure metals.

Kudryavtsevaite, Na3MgFe3+Ti4O12, a new kimberlitic mineral

Kudryavtsevaite, ideally Na3MgFe3+Ti4O12, is a new mineral from kimberlitic rocks of the Orapa area, Botswana. It occurs as rare prismatic crystals, up to 100 μm m across, associated with Mg-rich ilmenite, freudenbergite and ulvöspinel. Kudryavtsevaite is opaque with a vitreous lustre and shows a black streak. It is brittle; the Vickers hardness (VHN100) is 901 kg mm−2 (range: 876–925) (Mohs hardness ∼6). In reflected light, kudryavtsevaite is moderately bireflectant and very weakly pleochroic from dark grey to a slightly bluish grey. Under crossed polars, it is very weakly anisotropic with greyish-bluish rotation tints. Internal reflections are absent. Reflectance values (%), Rmin and Rmax, are: 21.3, 25.4 (471.1 nm), 20.6, 24.1 (548.3 nm), 20.0, 23.5 (586.6 nm) and 19.1, 22.4 (652.3 nm).Kudryavtsevaite is orthorhombic, space group Pnma, with a = 27.714(1), b = 2.9881(3), c = 11.3564(6) Å, V = 940.5(1) Å3, and Z = 4. The crystal structure [R1 = 0.0168 for 819 reflections with I > 2σ(I)] consists of edge-sharing and corner-sharing chains composed of Mg, Fe3+ and Ti atoms coordinated by six atoms of oxygen and running along the b axis, with Na filling the tunnels formed by the chains. The eight strongest powder-diffraction lines [d in Å (I/I0) (hkl)] are: 7.17 (100) (301), 4.84 (70) (302), 2.973 (35) (901), 2.841 (50) (004), 2.706 (50) (902), 2.541 (50) (312), 2.450 (70) (611), and 2.296 (45) (612). The average results of 12 electron microprobe analyses gave (wt.%): Na2O 16.46(15), CaO 1.01(3), MgO 5.31(5), Fe2O3 22.24(32), Cr2O3 1.05(6), Al2O3 0.03(2), TiO2 53.81(50), total 99.91, corresponding to the empirical formula (Na2.89Ca0.10)Σ2.99(Ti3.67Fe1.523+Mg0.72Cr0.08)Σ5.99O12, or ideally Na3MgFe3+Ti4O12.The new mineral has been approved by the IMA-CNMNC and named for Galina Kudryavtseva (1947–2006), a well known Russian mineralogist and founder of the Diamond Mineralogy Laboratory and scientific school for investigation of diamond mineralogy and geochemistry at the Lomonosov State University in Moscow, Russia.