J. A. R. Stirling

SIMS matrix effects in the analysis of light elements in silicate minerals: Comparison with SREF and EMPA data

Abstract Matrix effects in secondary-ion mass spectrometric (SIMS) analysis of light elements (H, Li, Be, B, and F) have been investigated in phenacite, kornerupine, danburite, axinite, spodumene, tourmaline, hambergite, and mica, all of which were epoxy-mounted in a known crystallographic orientation relative to the primary-ion beam. As reference chemical information, we used data from electron microprobe analysis (EMPA) and from single-crystal structure-refinement (SREF) on the same crystals used for SIMS. Quantification of secondary-ion intensities into concentrations was done using Si as the reference matrix element. The results indicate that matrix effects due to crystallographic orientation are <10% relative, or below analytical uncertainty for most analyzed elements. In dioctahedral mica, there is a difference in H/Si ion yield (IY) of ~25% relative when the crystal is analyzed parallel and orthogonal to the main cleavage (which is perpendicular to the c axis). The magnitude of this effect is significant and higher than our SIMS accuracy for H in micas: ±10% relative. Among the analyzed elements, Be is affected least by matrix effects, even when present as a major element. The most significant chemical effects on SIMS analysis of H, Li, F, and B in silicates seem to be related to the Fe (+Mn) content of the matrix: the light-element IY decreases as the Fe (+Mn) content increases, as previously seen in tourmaline, axinite, and kornerupine. Silicon and Al seem to have complementary and opposite effects on IY with respect to Fe and Mn. The agreement between SIMS and SREF is close for most light elements when they are present as major constituents. The results of our study also show that analytical problems are still present for B by EMPA, and this technique may not be adequate to measure B accurately in some minerals.

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.

Mobilization of gold in the deep crust: evidence from mafic intrusions in the Bamble belt, Norway

Abstract The location of mesothermal gold deposits in the upper part of major transcurrent shear zones suggests that gold was derived from the deep, wider portions of the shears. The 30 km-wide Bamble belt, south Norway, is a deep shear belt, metamorphosed to upper amphibolite and granulite grade at about 1.1 Ga. Preliminary studies showed that its rocks are strongly depleted in gold and other chalcophile elements. Mafic rocks were chosen for more detailed study of the mobilization of gold during metamorphism. Gold in mafic rocks largely partitions into the sulphide phase, which is mainly comprised of pyrrhotite. Modification of this phase was required to liberate gold. Bamble has two main groups of mafic rock. The first, metabasites, intruded before peak metamorphism, are uniformly low in gold. Their |O2 at peak metamorphism, obtained from ilmenite-orthopyroxene equilibria, indicates a strongly oxidized mineral assemblage, well above FMQ. Pyrrhotite was stable at peak temperature of 800°C, but on cooling below 600°C, internal (mineralogical) buffering by the oxidized assemblage caused the |O2 to cross into the stability field of pyrite. Following conversion of pyrrhotite to pyrite, the latter was partly replaced by magnetite. These serial changes in the mineralogical form of iron sulphide was conducive to the extraction of gold, as was the oxidized nature of the mineral assemblage that would have buffered metamorphic fluids to high |O2. The second group of mafic rocks, “hyperites”, intruded after peak metamorphism, record intermediate steps in the extraction of gold. These intrusions, of coronitic gabbro, were metamorphosed, in whole or in part, to amphibolite. There is a decrease in gold and other chalcophile elements across a hyperite dyke from the pyrrhotite-bearing, coronitic gabbro interior to the pyrite-bearing amphibolite margin.

Jadarite, LiNaSiB3O7(OH), a new mineral species from the Jadar Basin, Serbia

Jadarite, ideally LiNaSiB3O7(OH), is a new mineral species from the Jadar Basin, Serbia. It occurs as massive white aggregates, several metres thick, and is relatively free from inclusions and intergrowths; however, individual subhedral (tabular, elongate) to anhedral crystals rarely exceed 5–10 μm in size. It is associated with calcite, dolomite, K-feldspar, rutile, albite, ilmenite, pyrite, and fine-grained muscovite. Searlesite, analcime, chlorite, and quartz have also been identified. Jadarite is translucent (opaque in masses) with a porcellanous lustre (masses), possesses a white streak, is brittle with a platy habit and has an uneven to conchoidal fracture. VHN200 is 390 (range 343–426) kg/mm2. Mohs’ hardness is 4–5. It shows weak pink-orange fluorescence under both short- and long-wave ultraviolet radiation. An infra-red adsorption spectrum is given and shows strong, sharp peaks at 3490 and 3418 cm−1 which indicates that water is present as (OH) only. Peaks at 1409 and 1335 cm−1 indicate the presence of BO3 groups, and between 900 and 1180 cm−1 the probable presence of BO4. In transmitted light, plates and grains of jadarite show twinning in some crystallites and for λ 590 nm n α = 1.536(± 0.001) and n γ = 1.563(± 0.001). It is non-pleochroic, biaxial, and does not show parallel extinction. In plane-polarized reflected light, the mineral is dark grey with weak bireflectance, it is non-pleochroic and has abundant white internal reflections. Wet chemical analysis combined with CHN analyzer gave the following aggregate composition: Li2O 7.3, Na2O 15.0, SiO2 26.4, B2O3 47.2, H2O 4.3, total 100.2 wt.%. The empirical formula, based on 3B atoms per formula unit ( apfu ), is: Li1.08Na1.07Si0.97B3O6.99(OH)1.06. Jadarite is monoclinic ( P 21/ n ) with a 6.818(2), b 13.794(2), c 6.756(2) A, β 111.10(2)° V 592.8(2) A3 ( Z = 4), alternatively ( P 21/ c ) with a 6.756(3), b 13.794(2), c 7.680(3) A, β 124.07(3) °, V 592.9(4) A3 and Z = 4. The measured density (Berman Balance) is 2.45 g/cm3; calculated density is 2.46 g/cm3 (on the basis of the empirical formula and unit-cell parameters refined from powder data). The six strongest X-ray powder-diffraction lines [ d in A( I )( hkl )] are: 4.666 (62) (120, 021), 3.180 (82) (200), 3.152 (74) (002), 3.027 (40) (221), 2.946 (100) (131), 2.241 (74) (3 11,151), The mineral name is for the locality in Serbia where it was discovered during mineral exploration of the Jadar Basin.

Aurivilliusite, Hg2+Hg1+OI, a new mineral species from the Clear Creek claim, San Benito County, California, USA

Abstract Aurivilliusite, ideally Hg2+Hg1+OI, is monoclinic, C2/c, with unit-cell parameters refined from X-ray powder data: a = 17.580(6), b = 6.979(1), c = 6.693(3) Å , ß = 101.71(4)º, V = 804.0(5) Å3, a:b:c = 2.5190:1:0.9590,Z = 8. The strongest six lines of the X-ray powder-diffraction pattern [d in Å (I)(hkl)] are: 8.547(70)(200), 3.275(100)(002), 2.993(80)(2̅21), 2.873(80)(600), 2.404(50b)(6̅02, 421, 2̅22) and 1.878(50)(2̅23). This extremely rare mineral was collected from a small prospect pit near the longabandoned Clear Creek mercury mine, New Idria district, San Benito County, California, USA. It is intimately intermixed with another new undefined Hg-O-I phase (‘CCUK-15’), and is also closely associated with native mercury, cinnabar and edgarbaileyite in a host rock principally composed of quartz and magnesite. Aurivilliusite occurs in a cm-wide quartz vein predominantly as irregular-shaped thin patches ‘splattered’ on the quartz surface; patches vary in size from 10–20 μm up to 0.5 mm. The only known subhedral platy brightly reflecting crystal fragment, with major {100} form and distinct {100} cleavage, did not exceed 0.2 mm in longest dimension. The mineral is dark grey-black with a dark red-brown streak. Physical properties include: metallic lustre; opaque; non-fluorescent; brittle; uneven fracture; calculated density 8.96 g/cm3 (empirical formula), 8.99 g/cm3 (ideal formula). In polished section in plane-polarized reflected light, aurivilliusite resembles cinnabar, is extremely light sensitive, shows twinning and no internal reflections, and exhibits an unusual ‘red light’ coalescing phenomena. Averaged and corrected results of electron-microprobe analyses yielded HgO 40.10, Hg2O 38.62, I 22.76, Br 0.22, Cl 0.06, sum 101.76, less O = I + Br + Cl -1.46, total 100.30 wt.%, corresponding to Hg2+1.00Hg1+1.00O1.01(I0.97Br0.01Cl0.01)∑0.99, based on O + I + Br + Cl = 2 atoms per formula unit (a.p.f.u.). The original value for Hg, 74.27 wt.%, was partitioned in a HgO:Hg2O ratio of 1:1 after the discovery of the crystal-structure paper dealing with the synthetic equivalent of aurivilliusite. The mineral name is in honour of the late Dr Karin Aurivillius (1920−1982), chemistcrystallographer at the University of Lund, Sweden, for her significant contributions to the crystal chemistry of Hg-bearing inorganic compounds. Aurivilliusite is related chemically to terlinguaite, Hg2+Hg1+OCl, but has a different structure and X-ray characteristics.

LiNaSiB3O7(OH) – novel structure of the new borosilicate mineral jadarite determined from laboratory powder diffraction data

The structure of a new mineral jadarite, LiNaSiB(3)O(7)(OH) (IMA mineral 2006-36), has been determined by simulated annealing and Rietveld refinement of laboratory X-ray powder diffraction data. The structure contains a layer of corner-sharing, tetrahedrally coordinated Li, Si and B forming an unbranched vierer single layer, which is decorated with triangular BO(3) groups. The Na ion is situated between the tetrahedral layers in a distorted octahedral site. As the very high boron content in this mineral makes obtaining neutron diffraction data very problematic, ab initio optimization using VASP was used to validate the structure and to better localize the H atom. The H atom is located on the apex of the triangular BO(3) group and is involved in a weak intralayer hydrogen bond. The final Rietveld refinement agrees with the ab initio optimization with regard to a hydrogen bond between the H atom and one of the tetrahedral corner O atoms. The refined structure seems to be of a remarkably high quality given the complexity of the structure, the high proportion of very light elements and the fact that it was determined from relatively low-resolution laboratory data over a limited 2theta range (10-90 degrees 2theta).

Dukeite, Bi243+Cr86+O57(OH)6(H2O)3, a new mineral from Brejaúba, Minas Gerais, Brazil: Description and crystal structure

Abstract Dukeite, Bi3+24Cr86+O57(OH)6(H2O)3, space group P31c, a = 15.067(3), c = 15.293(4) Å, V = 3007(1) Å3, Z = 2, is a new mineral found on a museum specimen labeled as originating from the São José Mine, Brejaúba, Minas Gerais, Brazil. The strongest seven lines of the X-ray powder-diffraction pattern [d in Å (I) (hkl)] are: 7.650 (50) (002), 3.812 (40) (004), 3.382 (100) (222), 2.681 (70) (224), 2.175 (40) (600), 2.106 (40) (226), 1.701 (50) (228). It occurs as groupings of tightly bound 1 × 0.3 mm2 sized sheaves that are associated with pucherite, schumacherite, bismutite, and hechtsbergite. Individual acicular crystals do not exceed 100 μm in length by 1-2 μm in width. Crystals are yellow inclining to a dirty yellow-brown, possess a bright yellow streak, are transparent, brittle, resinous, and do not fluoresce under ultraviolet light. The estimated Mohs hardness is between 3 and 4, the calculated density (for the empirical formula) is 7.171 g/cm3, and the mineral is slowly soluble in concentrated HCl. Electron-microprobe analyses yielded Bi2O3 85.06, CrO3 11.65, V2O5 0.59, H2O (calc.) [1.67], total [98.97] wt%. The empirical formula, derived from the crystalstructure analysis and electron-microprobe analyses, is Bi3+23.95(Cr6+7.64V5+0.43)Σ8.07O56.84(OH)6.16⋅3.01 H2O, based on O = 66. In reflected plane-polarized light in air it is gray to purplish gray with strong yellow internal reflections. Bireflectance is very weak. Measured reflectance values, in air and in oil, are tabulated: indices of refraction calculated from these at 590 nm are 2.33 and 2.37. The name honors Duke University, Durham, North Carolina, in whose collection the mineral was found and also recognizes the contribution of the Duke family to the advancement of scientific knowledge. The crystal structure of dukeite was solved by direct methods and refined on the basis of F2 using all unique reflections measured with MoKα X-radiation on a CCD-equipped diffractometer. The final R1 index was 8.7%, calculated using 1033 observed reflections. It contains irregular layers of Biφn polyhedra (φ: O, OH-, H2O) parallel to (001), separated and connected by CrO4 tetrahedra to form a framework structure. One CrO4 tetrahedron shares all of its vertices with Biφn polyhedra, whereas the other three CrO4 tetrahedra share only three vertices each with the Biφn polyhedra on either side

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.

Carlosbarbosaite, ideally (UO2)2Nb2O6(OH)2·2H2O, a new hydrated uranyl niobate mineral with tunnels from Jaguaraçu, Minas Gerais, Brazil: description and crystal structure

Abstract Carlosbarbosaite, ideally (UO2)2Nb2O6(OH)2 ·2H2O, is a new mineral which occurs as a late cavity filling in albite in the Jaguaraçu pegmatite, Jaguaraçu municipality, Minas Gerais, Brazil. The name honours Carlos do Prado Barbosa (1917-2003). Carlosbarbosaite forms long flattened lath-like crystals with a very simple orthorhombic morphology. The crystals are elongated along [001] and flattened on (100); they are up to 120 μm long and 2-5 μm thick. The colour is cream to pale yellow, the streak yellowish white and the lustre vitreous. The mineral is transparent (as individual crystals) to translucent (massive). It is not fluorescent under either long-wave or short-wave ultraviolet radiation. Carlosbarbosaite is biaxial(+) with α = 1.760(5), β = 1.775(5), γ = 1.795(5), 2Vmeas. = 70(1)°, 2Vcalc. = 83°. The orientation is X ∥ a, Y ∥ b, Z ∥ c. Pleochroism is weak, in yellowish green shades, which are most intense in the Z direction. Two samples were analysed. For sample 1, the composition is: UO3 54.52, CaO 2.07, Ce2O3 0.33, Nd2O3 0.49, Nb2O5 14.11, Ta2O5 15.25, TiO2 2.20, SiO2 2.14, Fe2O3 1.08, Al2O3 0.73, H2O (calc.) 11.49, total 104.41 wt.%; the empirical formula is (⃞0.68Ca0.28Nd0.02Ce0.02)∑=1.00[U1.44⃞0.56O2.88(H2O)1.12](Nb0.80Ta0.52Si0.27Ti0.21Al0.11Fe0.10)∑=2.01O4.72(OH)3.20(H2O)2.08. For sample 2, the composition is: UO3 41.83, CaO 2.10, Ce2O3 0.31, Nd2O3 1.12, Nb2O5 14.64, Ta2O5 16.34, TiO2 0.95, SiO2 3.55, Fe2O3 0.89, Al2O3 0.71, H2O (calc.) 14.99, total 97.43 wt.%; the empirical formula is (⃞0.67Ca0.27Nd0.05Ce0.01)∑=1.00[U1.04⃞0.96O2.08(H2O)1.92] (Nb0.79Ta0.53Si0.42Ti0.08Al0.10Fe0.08)∑=2.00O4.00(OH)3.96(H2O)2.04. The ideal endmember formula is (UO2)2Nb2O6(OH)2 ·2H2O. Calculated densities are 4.713 g cm-3 (sample 1) and 4.172 g cm-3 (sample 2). Infrared spectra show that both (OH) and H2O are present. The strongest eight X-ray powder- diffraction lines [listed as d in Å(I)(hkl)] are: 8.405(8)(110), 7.081(10)(200), 4.201(9)(220), 3.333(6)(202), 3.053(8)(022), 2.931(7)(420), 2.803(6)(222) and 2.589(5)(040,402). The crystal structure was solved using single-crystal X-ray diffraction (R = 0.037) which gave the following data: orthorhombic, Cmcm, a = 14.150(6), b = 10.395(4), c = 7.529(3) Å, V = 1107(1) Å3, Z= 4. The crystal structure contains a single U site with an appreciable deficiency in electron scattering, which is populated by U atoms and vacancies. The U site is surrounded by seven O atoms in a pentagonal bipyramidal arrangement. The Nb site is coordinated by four O atoms and two OH groups in an octahedral arrangement. The half-occupied tunnel Ca site is coordinated by four O atoms and four H2O groups. Octahedrally coordinated Nb polyhedra share edges and corners to form Nb2O6(OH)2 double chains, and edge-sharing pentagonal bipyramidal U polyhedra form UO5 chains. The Nb2O6(OH)2 and UO5 chains share edges to form an open U-Nb-φ framework with tunnels along [001] that contain Ca(H2O)4 clusters. Carlosbarbosaite is closely related to a family of synthetic U-Nb-O framework tunnel structures, it differs in that is has an (OH)-bearing framework and Ca(H2O)4 tunnel occupant. The structure of carlosbarbosaite resembles that of holfertite.

Brumadoite, a new copper tellurate hydrate, from Brumado, Bahia, Brazil

Abstract Brumadoite, ideally Cu3Te6+O4(OH)4·5H2O, is a new mineral from Pedra Preta mine, Serra das Éguas, Brumado, Bahia, Brazil. It occurs as microcrystalline aggregates both on and, rarely, pseudomorphous after coarse-grained magnesite, associated with mottramite and quartz. Crystals are platy, subhedral, 1-2 μm in size. Brumadoite is blue (near RHS 114B), has a pale blue streak and a vitreous lustre. It is transparent to translucent and does not fluoresce. The empirical formula is (Cu2.90Pb0.04Ca0.01)∑2.95 (Te0.934+Si0.05)∑0.98O3.92(OH)3.84·5.24H2O. Infrared spectra clearly show both (OH) and H2O. Microchemical spot tests using a KI solutionshow that brumadoite has tellurium inthe 6+ state. The mineral is monoclinic, P21/m or P21. Unit-cell parameters refined from X-ray powder data are a 8.629(2) Å , b 5.805(2) Å , c 7.654(2) Å , β 103.17(2)º, V 373.3(2) Å3, Z = 2. The eight strongest X-ray powder-diffractionlin es [d in Å,(I),(hkl)] are: 8.432,(100),(100); 3.162,(66),(2̅02); 2.385,(27),(220); 2.291,(12),(1̅22); 1.916,(11),(312); 1.666,(14),(4̅22,114); 1.452,(10),(323,040); 1.450,(10),(422,403). The name is for the type locality, Brumado, Bahia, Brazil. The new mineral species has been approved by the CNMNC (IMA 2008-028).