Robert A. Gault

Kochite, a new member of the rosenbuschite group from the Werner Bjerge alkaline complex, East Greenland

Kochite, ideally Na 2 (Na,Ca) 4 Ca 4 (Mn,Ca) 2 Zr 2 Ti 2 (Si 2 O 7 ) 4 (O,F) 4 F 4 , is a new member of the rosenbuschite group from the alkaline complex of Werner Bjerge, East Greenland. It occurs in nepheline syenite as lath-shaped to acicular crystals in aggregates up to 0.3 × 1.0 mm. Associated minerals are nepheline, alkali feldspar and lavenite. It is transparent with a brownish colour and has a vitreous lustre. It is brittle with a perfect {100} cleavage and an uneven fracture. The mineral is biaxial positive with α 1.684 ± .002, β 1.695 ± .004, γ 1.718 ± .002 and 2 V meas. = 73°(2). The optical orientation is X = c and Z Λ [100] ∼ 20°. The pleochroism is weak with X = colourless and Z = pale yellow. The mineral is triclinic with a = 10.032(2), b = 11.333(2), c = 7.202(1) A, α = 90.192(4), β = 100.334(5), γ = 111.551(4) °, Z = 1. The 5 strongest X-ray lines are [ d in A (Int.)] 2.908(10), 2.600(8), 3.028(6), 1.868(6) and 1.670(5). An average of four electron microprobe analyses of kochite gave SiO 2 31.55, Al 2 O 3 0.05, V 2 O 3 0.03, TiO 2 8.44, ZrO 2 12.12, HfO 2 0.09, Nb 2 O 5 1.86, Ta 2 O 5 0.02, MgO 0.01, MnO 4.92, FeO 1.08, CaO 21.39, SrO 0.12, Na 2 O 10.33, Y 2 O 3 0.39, La 2 O 3 0.25, Ce 2 O 3 0.57, F 6.83, O ≡ F 2.88, total 97.71 wt.%. The empirical formula, based on 8 Si atoms in accordance with the structure refinement ( R ( F ) = 4.0 %), is (Na 1.70 Sr 0.02 )∑ 1.72 (Na 2.77 Ca 1.23 )∑ 4.00 (Ca 3.40 Na 0.60 )∑ 4.00 (Mn 1.06 Ca 0.82 Y 0.05 Ce 0.05 La 0.02 )∑ 2.00 (Zr 1.40 Fe 0.23 Ca 0.36 Hf 0.01 )∑ 2.00 (Ti 1.61 Nb 0.21 Zr 0.10 Al 0.05 V 0.03 )∑ 2.00 (Si 2 O 7 ) 4 F 4 (O 2.39 F 1.48 )∑ 3.87 . D meas. = 3.32, D calc. = 3.31 g/cm 3 . Kochite is an Mn − , Ti-analogue of rosenbuschite.

Paganoite, NiBi 3+ As 5+ O 5 , a new mineral from Johanngeorgenstadt, Saxony, Germany: description and crystal structure

Paganoite, ideally NiBi 3+ As 5+ O 5 , triclinic space group P1, a = 6.7127(8), b = 6.8293(8), c = 5.2345(6) A, α = 107.625(2)°, β = 95.409(2)°, γ = 111.158(2)°, V = 207.62 A 3 , a:b:c: = 0.9829:1:0.7665, Z = 2, is a new mineral found on a single nickeline-veined quartz specimen from Johanngeorgenstadt, Saxony, Germany. The strongest seven lines of the X-ray powder-diffraction pattern [ d in A ( hkl )] are: 5.943 (100) (010); 3.233 (100) (011); 3.067 (60) (021); 3.047 (50) (200); 2.116 (50) (112,031, 311,122,231); 2.095 (40) (230,102); 1.659 (40) (420). It occurs as isolated orange-brown to deep-golden-brown crystals and crystal aggregates which are always intimately associated with aerugite; additional associations include bunsenite, xanthiosite, rooseveltite, native bismuth and two undefined arsenates. Individual prismatic crystals are subhedral to euhedral, elongate along [010] with a length-to-width ratio of 3:1, and average 0.3 mm in longest dimension. Forms observed are {100} major, {010} minor, {001} minor and perhaps { hOl } minor. Crystals possess a very pale orange-brown streak, are transparent (crystals) to translucent (aggregates), brittle, adamantine (almost gemmy), and do not fluoresce under ultraviolet light. The mineral shows neither twinning nor cleavage, has an uneven fracture, and the calculated density (for the empirical formula) is 6.715 g/cm 3 . Electron-microprobe analyses yielded NiO 15.37, CoO 2.05, Bi 2 O 3 55.06, As 2 O 5 28.0, total 100.48 wt.% The empirical formula, derived from the crystal-structure analysis and electron-microprobe analyses, is (Ni 2+ 0.86 C 2+ 0.11 ) Σ0.97 Bi 3+ 0.99 As 5+ 1.02 O 5 , based on O = 5. In reflected plane-polarized light in air, it is grey with no obvious internal reflections, bireflectance or pleochroism. Measured reflectance values, in air and in oil, are tabulated: indices of refraction calculated from these at 589 nm are 2.07 and 2.09. The name honours Renato and Adriana Pagano for their long-standing service to the European mineralogical community. The crystal structure of paganoite has been solved by direct methods and refined on the basis of F 2 using 977 unique reflections measured with Mo K α X-radiation on a diffractometer equipped with a CCD-based detector. The final R 1 was 4.4%, calculated for the 926 observed reflections. The structure contains AsO 4 tetrahedra and distorted Ni 2+ O 6 octahedra, as well as one-sided Bi 3+ O 5 polyhedra due to the presence of an s 2 lone pair of electrons on the Bi 3+ cation. The structure is an open framework composed of dimers of edge-sharing NiO 6 octahedra that are linked by vertex-sharing with AsO 4 tetrahedra. Bi 3+ cations occur within voids in the framework, and bond only to framework elements. The structure of paganoite is very closely related to that of jagowerite, BaAl 2 P 2 O 8 (OH) 2 , which possesses an identical framework of octahedra and tetrahedra.

Crystal-structure refinement of a Zn-rich kupletskite from Mont Saint-Hilaire, Quebec, with contributions to the geochemistry of zinc in peralkaline environments

Abstract The chemistry and crystal structure of a unique Zn-rich kupletskite: (K1.55Na0.21Rb0.09Sr0.01)Σ1.86(Na0.82Ca0.18)Σ1.00(Mn4.72Zn1.66Na0.41Mg0.12Fe2+0.09)Σ7.00(Ti1.85Nb0.11Hf0.03)Σ1.99(Si7.99Al0.12)Σ8.11O26(OH)4(F0.77OH0.23)Σ1.00, from analkaline pegmatite at Mont Saint-Hilaire, Quebec, Canada has been determined. Zn-rich kupletskite is triclinic, P1̅, a = 5.3765(4), b = 11.8893(11), c = 11.6997(10), α = 113.070(3), β = 94.775(2), γ = 103.089(3), R1 = 0.0570 for 3757 observed reflections with Fo > 4σ(Fo). From the single-crystal X-ray diffraction refinement, it is clear that Zn2+ shows a preference for the smaller, trans M(4) site (69%), yet is distributed amongst all three octahedral sites coordinated by 4 O2− and 2 OH− [M(2) 58% and M(3) 60%]. Of note is the lack of Zn in M(1), the larger and least-distorted of the four crystallographic sites, with an asymmetric anionic arrangement of 5 O2− and 1 OH−. The preference of Zn for octahedral sites coordinated by mixed ligands (O and OH) is characteristic of its behaviour in alkaline systems, in contrast to granitic systems where Zn tends to favour [4]-coordinated, OH- and H2O-free sites with only one ligand species (O, S, Cl, B, I). In alkaline systems, [4]Zn is only present in early sphalerite or in late-stage zeolite-like minerals. The bulk of Zn in alkaline systems is present as discrete [6]Zn phases such as members of the astrophyllite, labuntsovite, milarite and nordite groups, a result of the formation of network-forming Zn(OH)42− complexes in the low-temperature, low-fS₂, high-alkalinity and highly oxidizing systems.

Petewilliamsite, (Ni, Co)30(As2O7)15, a new mineral from Johanngeorgenstadt, Saxony, Germany: description and crystal structure

Abstract Petewilliamsite, ideally (Ni,Co)30(As2O7)15, monoclinic, space group C2, a = 33.256(5), b = 8.482(1), c = 14.191(2) Å , ß = 104.145(3)º , V = 3881.6(11) Å3, a:b:c = 3.9209:1:1.6731, Z = 2, is a new mineral found on a single nickeline-veined quartz specimen from Johanngeorgenstadt, Saxony, Germany. The mineral possesses a pronounced subcell-supercell: a (subcell) = 1/5 a (supercell); b (subcell) = b (supercell); c (subcell) = 1/3 c (supercell), and the strongest six lines of the X-ray powder-diffraction pattern are [d in Å (I) (hkl)]: 4.235(30)(020) ; 3.118(100)(513 , 023); 3.005(60)(1̅0̅03); 2.567(50)( 1020); 1.637(50)(536 ); 1.507(30b)(553, 1533, 2̅0̅06). It occurs predominantly as scattered patches of mm-sized aggregates which are intimately associated with varicoloured xanthiosite; additional associations include bunsenite, aerugite, rooseveltite, native bismuth, paganoite and two undefined arsenates. Subhedral equant crystals with rounded faces are intimately intergrown in 1 mm-sized aggregates and individual grains do not exceed 0.5 mm in maximum diameter. The average crystal size is variable from 20 μm to 0.3 mm. The colour varies from dark violet-red to dark brownish-red and the streak is pale reddish-brown to pale purplish-brown. Crystals are translucent, brittle, vitreous, and do not fluoresce under ultraviolet light. The mineral shows neither twinning nor cleavage, has an uneven fracture, and the calculated density (for the empirical formula) is 4.904 g/cm3. Electron-microprobe analyses gave NiO 19.45, CoO 18.39, CuO 3.40, CaO 0.17, FeO 0.04, As2O5 60.32, total 101.77 wt.%. The empirical formula, derived from crystal-structure analysis and electron-microprobe analyses, is (Ni14.662+ Co13.822+ Cu2.412+ Ca0.17Fe0.032+ )∑31.09(As1.975+ O7)15, based on O = 105 atoms per formula unit (a.p.f.u.). In reflected plane-polarized light in air, petewilliamsite is dark grey with orange to spectral (multicoloured) internal reflections and no obvious bireflectance, anisotropy or pleochroism. Measured reflectance values in air are tabulated; the index of refraction calculated at 589 nm is 1.88. The mineral name honours Professor Peter (‘Pete’) Allan Williams of the University of Western Sydney, New South Wales, Australia, for his contributions to the study of secondary minerals. The crystal structure of petewilliamsite has been solved by direct methods and refined on the basis of F2 using 9212 unique reflections measured with Mo-Kα X-radiation on a diffractometer equipped with a CCD-based detector. The final R1 was 7.68%, calculated for 1273 observed reflections. The structure contains 15 symmetrically distinct As5+ cations, each of which is tetrahedrally coordinated by four O atoms, and pairs of these AsO4 tetrahedra share a vertex which results in As2O7 pyroarsenate groups that are in layers parallel to (010). The structure also has 16 distinct transition-metal M (M: Ni,Co) sites of which there are one tetrahedral, four square bipyramidal, and 11 octahedral arrangements. Adjacent pyroarsenate groups are linked through bonds to M cations. The structure of petewilliamsite is not closely related to other naturally occurring arsenates and it is the first pyroarsenate mineral.

Reederite-(Y), a new sodium rare-earth carbonate mineral with a unique fluorosulfate anion

Abstract Reederite-(Y), ideally, (Na,Mn,Fe)15(Y,REE)2(CO3)(SO3F)Cl, is a new mineral from Mont-Saint-Hilaire, Quebec. It occurs as blocky, yellow to orange-brown grains up to 2 mm. Associated minerals include trona, shortite, petersenite-(Ce), catapleiite, minor analcime, and manganotychite. The mineral has a vitreous luster and white streak. It is soft (Mohs hardness 3-3.5) and brittle, with a conchoidal fracture and perfect {001} cleavage. Reederite-(Y) is uniaxial negative, ω = 1.548(1) and ε = 1.537(1). It is hexagonal, space group P6̅, a = 8.773(1), c = 10.746(2) Å, and Z = 1. The strongest X-ray powder diffraction lines are [d (Å), I, (hkl)] 2.532, 100, (212); 4.39, 80 (102); 2.774, 80, (113); 2.240, 80, (213); 6.20,40, (101); 1.657,40 (116,314,322,410); and 2.067,30, (105,303). The infrared spectrum is given. An electron microprobe analysis gave Na2O 34.04, CaO 0.70, MnO 1.23, Al2O3 1.31, Y2O3 10.24, La2O3 1.39, Ce2O3 3.54, Nd2O3 1.99, Er2O3 1.19, DY2O3 1.39 (plus minor amounts of Fe, Pr, Sm, Gd, and Yb oxides), SO3 5.07, CO2 (calc) 31.91, F 1.86, and Cl 2.05, -O ≡ F + Cl 1.24, total 99.14 wt%. Dmeas= 2.91 g/cm3, Dcalc= 2.85 g/cm3. The structure has been refined to R = 3.2%. The carbonate layers are thick slabs accommodating (CO3)2- groups oriented perpendicular to the {001} layering, the large cation polyhedra, and the Cl- and (SO3F)- anions. The Na atoms adopt a variety of distinct coordinations. This is the first reported natural occurrence of a fluorosulfate anion.

Arisite-(La), a new REE-fluorcarbonate mineral from the Aris phonolite (Namibia), with descriptions of the crystal structures of arisite-(La) and arisite-(Ce)

Abstract Arisite-(La), ideally NaLa2(CO3)2[F2x(CO3)1−x]F, is a new layered REE-fluorcarbonate mineral from miarolitic cavities within the Aris phonolite, Namibia (IMA no. 2009-019). It occurs as distinct chemical zones mixed with its Ce-analogue, arisite-(Ce). Crystals are vitreous, transparent beige, beige-yellow, light lemon-yellow to pinkish, and occur as tabular prisms up to 1.5 mm. Arisite-(La) is brittle, has conchoidal fracture, poor cleavage perpendicular to (001), a Mohs hardness of ~3−3½, is not fluorescent in either long- or shortwave UV radiation, dissolves slowly in dilute HCl at room temperature and sinks in methylene iodide, Dcalc. = 4.072 g cm−3. Arisite-(La) is uniaxial negative, has sharp extinction, with both ω and Ɛ exhibiting a range of values within each grain: ω = 1.696−1.717(4) and Ɛ = 1.594−1.611(3), a result of chemical zoning attributed to both Ce ⇌ La and Na ⇌ Ca substitutions. The crystal structure of both arisite-(Ce) and arisite-(La) were solved by direct methods and refined to R = 1.66%, wR2 = 4.31% (Ce) and R = 2.09%, wR2 = 5.26% (La), respectively. Arisite is hexagonal, P6̅m2, Z = 1, withunit-cell parameters of a = 5.1109(2) Å, c = 8.6713(4) Å, V = 196.16(6) Å3 for arisite-(Ce), and a = 5.1131(7) Å, c = 8.6759(17) Å, V = 196.43(5) Å3 for arisite-(La). Arisite-(Ce) and arisite-(La) are members of the layered, flat-lying REE-fluorcarbonate group which have crystal structures characterized by separate layers of triangular planar CO32− groups that parallel the overall layering of the structure, F, REE and alkali or alkaline-earth elements. Overall, the arisite structure can be defined by three distinct layers which parallel (001): (1) ∞[REE(CO3)2F] slabs, (2) sheets of Naϕ9 polyhedra, and (3) ∞[2F/CO3]. Based on its (M+F)/C ratio, arisite can further be described as having a dense, flat-lying fluorcarbonate structure, a classification which includes the structurally related mineral species cordylite, kukharenkoite, cebaite, lukechangite, huanghoite, and one incompletely characterized synthetic phase, NaY2(CO3)3F.

Juabite, Cu 5 (Te (super 6+) O 4 ) 2 (As (super 5+) O 4 ) 2 .3H 2 O, a new mineral species from the Centennial Eureka Mine, Juab County, Utah

Abstract Juabite, ideally Cus(Te6+O4)2(AsS5+O4)2·3H20, is triclinic, space-group choices Pl(1) or P1̅(2), with unit-cell parameters refined from powder data: a = 8.984(5), b = 10.079(7), c = 8.975(5) Å,α = 102.68(7) °, β = 92.45(6)° , γ = 70.45(5) ° V = 746.8(8) Å, a:b:c =o 0.8914:1:0.8905, Z = 2. The strongest seven reflections of the X-raypowder-diffraction pattern [d in Å (i)(hkl)] are: 9.28 (70)(010), 4.65−(70)(020), 3.097 (100)(030,2̅11), 3.018 (60)(212), 2.658 (50)(3̅01), 2.468 (50)(2̅22̅) and 1.740 (50)(1̅15̅, 521, 1̅51̅). The mineral is an extremely rare constituent on the dumps of the Centennial Eureka mine, Juab County, Utah, U.S.A., where it occurs as crystalline platy masses that average 0.2−0.3 mm in longest dimension within small interconnected vugs of drusy quartz. Associated minerals are enargite, beudantite, and an undefined, possible Pb-analogue of arsenobismite. Individual crystals are subhedral to euhedral and average 125 × 100 × 1−2 μm in size. Cleavage {010} perfect. Forms are: {010} major; {100}, {1̅01}, and {101} minor. The mineral is translucent (masses) to transparent (crystals), emerald-green, with a pale green streak, and an uneven to subconchoidal fracture. Juabite is vitreous to adamantine (almost gemmy) on cleavage faces, brittle, and nonfluorescent; H (Mohs) 3−4; D (calc.) 4.59 g/cm3 for the idealised formula. In polished section, juabite is white in plane-polarised reflected light in air with ubiquitous turquoise-blue internal reflections; bireflectance and anisotropy are unknown (due to interference from internal reflections). Averaged electronmicroprobe analyses yielded CuO 38.25, PbO 0.57, TeO3 32.58, As205 22.81, H20 (calc. assuming 3H20) [5.19], total [99.40] wt.%, leading to the empirical formula (Cu5.01Pb0.03)∑5.04(TeO4)1.93 (AsO4)2.07·3.00H2O based on O = 19. The infrared absorption spectrum shows definite bands for structural H20 with an O-H stretching frequency centred at 3283 cm−1 and a H-O-H flexing frequency centred at 1642 cm−1. The mineral name is for the county within the state of Utah in which the Centennial Eureka mine is located.

Leisingite, Cu(Mg,Cu,Fe,Zn) 2 Te (super 6+) O 6 .6H 2 O, a new mineral species from the Centennial Eureka Mine, Juab County, Utah

Abstract Leisingite, ideally Cu(Mg,Cu,Fe,Zn)2Te6+O6·6H2O, is hexagonal, P3 (143), with unit-cell parameters refined from powder data: a = 5.305(1), c = 9.693(6) Å, V = 236.2(2) Å3, c/a = 1.8271, Z = 1. The strongest six reflections of the X-ray powder-diffraction pattern [d in Å (I) (hkl)] are: 9.70 (100) (001), 4.834 (80) (002), 4.604 (60) (100), 2.655 (60) (110), 2.556 (70) (111) and 2.326 (70) (112). The mineral is found on the dumps of the Centennial Eureka mine, Juab County, Utah, U.S.A. where it occurs as isolated, or rarely as clusters of, hexagonal-shaped very thin plates or foliated masses in small vugs of crumbly to drusy white to colourless quartz. Associated minerals are jensenite, cesbronite and hematite. Individual crystals are subhedral to euhedral and average less than 0.1 mm in size. Cleavage {001} perfect. Forms are: {001} major; {100}, {110} minute. The mineral is transparent to somewhat translucent, pale yellow to pale orange-yellow, with a pale yellow streak and an uneven fracture. Leisingite is vitreous with a somewhat satiny to frosted appearance, brittle to somewhat flexible and nonfluorescent; H(Mohs) 3-4; D(calc.) 3.41 for the idealized formula; uniaxial negative, ω = 1.803(3), ɛ = 1.581 (calc.). Averaged electron-microprobe analyses yielded CuO 24.71, FeO 6.86, MgO 6.19, ZnO 0.45, TeO3 36.94, H2O (calc.) [21.55], total [96.70] wt.%, leading to the empirical formula Cu1.00(Mg0.77Cu0.56Fe0.48Zn0.03)Σ1.84Te1.066+O6.02·5.98H2O based on O = 12. The infrared absorption spectrum shows definite bands for structural H2O with an O-H stretching frequency centered at 3253 cm−1 and a H-O-H flexing frequency centered at 1670 cm−1. The mineral name honours Joseph F. Leising, Reno, Nevada, who helped collect the discovery specimens.