Hubert Putz

Barikaite, Pb10Ag3(Sb8As11)Σ19S40, a new member of the sartorite homologous series

Abstract Barikaite, ideally Pb10Ag3(Sb8As11)∑19S40, is a new mineral species from the Barika Au-Ag deposit, Azarbaijan Province, western Iran. It was formed in fractures developed in silica bands situated in massive banded pyrite and baryte ores. These fractures house veinlets that contain a number of Ag-As- Sb-Pb-rich sulfosalts, tetrahedrite-tennantite, realgar, pyrite and electrum. Barikaite appears as inclusions in guettardite. The mineral is opaque, greyish black with a metallic lustre; it is brittle without any discernible cleavage. In reflected light barikaite is greyish white, pleochroism is distinct, white to dark grey. Internal reflections are absent. In crossed polars, anisotropism is distinct with rotation tints in shades of grey. The reflectance data (%, in air) are: 37.0, 39.3 at 470 nm, 34.1, 36.9 at 546 nm, 33.1, 36.2 at 589 nm and 31.3, 34.1 at 650 nm. The Mohs hardness is 3-3½, microhardness VHN50 exhibits the range 192-212, with a mean value of 200 kg mm-2. The average results of five electron-microprobe analyses in a grain are (in wt.%): Pb 35.77(33), Ag 5.8(1), Tl 0.15(08), Sb 18.33(09), As 15.64(16), S 24.00(15), total 99.69(10) wt.%, corresponding to Pb9.31Ag2.90Tl0.04(Sb8.12As11.26)∑19.36S40.37 (on the basis of 32Me + 40S = 72 a.p.f.u.). The simplified formula, Pb10Ag3(Sb8As11)∑19S40, is in accordance with the results of a crystal-structure analysis, and requires Pb 37.89, Ag 5.91, Sb 17.79, As 15.05 and S 23.42 (wt.%). The variation of chemical composition is minor, the empirical formula ranging from Pb10.39Ag2.32Tl0.02Sb7.52As11.27S40.49 to Pb9.24Ag2.93Tl0.04Sb8.13As11.35S40.31. Barikaite has monoclinic symmetry, space group P21/n and unit-cell parameters a 8.5325(7) Å, b 8.0749(7) Å, c 24.828(2) Å, and β 99.077(6)°, Z = 1. Calculated density for the empirical formula is 5.34 (g cm-3). The strongest eight lines in the (calculated) powder-diffraction pattern [d in Å (I)(hkl)] are: 3.835(63)(022), 3.646(100)(016), 3.441(60)(212), 3.408(62)(2̄14), 2.972(66)(2̄16), 2.769(91)(222), 2.752(78)(4̄24) and 2.133(54)(402). Barikaite is the N = 4 member of the sartorite homologous series with a near-equal role of As and Sb, which have an ordered distribution pattern in the structure. It is a close homeotype of rathite and more distantly related to dufrénoysite (both distinct, pure arsenian N = 4 members) and it completes the spectrum of Sb-rich members of the sartorite homologous series. The new mineral and its name have been approved by the IMA-CNMNC (IMA 2012-055).

Chovanite, Pb15−2xSb14+2xS36Ox (x ~ 0.2), a new sulphosalt species from the Low Tatra Mountains, Western Carpathians, Slovakia

Chovanite, a new representative of the group of oxysulphosalts of Pb and Sb was found in three hydrothermal deposits of antimony ore, Dubrava, Male ´ ˇ Zelezne ´, and Klacianka, situated on the northern slopes of the Low Tatra Mountains, Slovakia. It is associated with other Pb-Sb sulphosalts, especially boulangerite, robinsonite and dadsonite. In reflected light, chovanite is white, bireflectance is distinct already in air. Pleochroism is present; colour varies from white with a yellowish green tint (darkest position) to white with a faint bluish tint (lightest position). Reflectance values in air are Rmax -R min (%) (l nm): 43.6-37.7 (470), 43.0-36.7 (546), 41.3-35.4 (589), 39.2-34.0 (650). Anisotropy is moderate to strong both in air and in oil, with blue grey to brown grey polarization colours. Internal reflections and twinning are absent. The optical properties are very similar to boulangerite. Micro-indentation hardness is 222.5 with a range 213-238. Derived Mohs hardness is 3. Cleavage is good, parallel to the c axis. Simplified chemical formula based on electron-microprobe analyses is Pb14.42(35)Sb14.33(11)S36.04(23), Z ¼ 4, which corresponds to Pb 50.74, Sb 29.63, S 19.62, total 100.00 wt%. No other elements exceed detection limits; chlorine is absent and oxygen was not measured. Structural formula is Pb15-2xSb14þ2xS36Ox (Z ¼ 4) for which the above mean of microprobe measurement data and the structure refinement give the value of x equal to � 0.2. Density (calc.) is 7.14 g/cm 3 . Crystal system is monoclinic, space group C2/m, lattice parameters a ¼ 48.189(48) A ˚ , b ¼ 4.1104(40) A ˚ , c ¼ 34.235(35) A ˚ , b ¼ 106.059(15) � , V ¼ 6517(11) A ˚ 3 , Z ¼ 4. Chovanite belongs to a sulphosalt family of boxwork structures, together with pellouxite, scainiite, pillaite, marruccite, vurroite, neyite, and several synthetic sulphosalts. Its crystal structure contains 11 independent lead sites, 13 coordination polyhedra of antimony, some of them with Sb sites split into two partially occupied non-overlapping positions, and five mixed Pb, Sb sites. The boxwork structure of chovanite is formed by a combination of three types of structural modules: (a) continuous walls with a complex structure of rod-layer type; these walls are interconnected by (b) rod-like partitions, and the resulting box-like channels (c) are filled by still another type of structure rods. Chovanite has the largest box-like channel system and infill elements known at present. In spite of differences in chemical composition, chovanite is structurally closest to pellouxite (Cu,Ag)2Pb21Sb23S55ClO which has a moderately large boxwork channel system.

Daliranite, PbHgAs 2 S 6 , a new sulphosalt from the Zarshouran Au-As deposit, Takab region, Iran

Abstract Daliranite, ideally PbHgAs2S6, occurs as a rare sulphosalt species at the Carlin-type Zarshouran Au-As deposit North of the town of Takab in the Province of West Azarbaijan, Iran. The new species is associated with orpiment, rarely with galkhaite, hutchinsonite and cinnabar. The strongly silicified matrix of the specimens has veinlets of sphalerite, with rare inclusions of galena and various (Cu)-Pb-As(Sb) sulphosalts. Daliranite occurs as matted nests of acicular and flexible fibres up to 200 μm in length and a width less than a few μm. The colour is orange-red with a pale orange-red streak and the lustre is adamantine. The mineral is transparent and does not fluoresce. The Mohs hardness is <2. Electron microprobe analyses give the empirical formula Pb0.95Tl0.01Hg1.04As2.10S5.91, ideally PbHgAs2S6; the calculated density is 5.93 g cm−3. Unit-cell parameters were determined by an electron-diffraction study and refined from X-ray powder data. Daliranite is monoclinic primitive with a = 19.113(5) Å, b = 4.233(2) Å, c = 22.958(8) Å, β = 114.78(5)°, V = 1686.4 Å3 and Z = 8, a:b:c = 4.515:1:5.424, space group P2, Pm or P2/m. The strongest X-ray powder-diffraction lines [d in Å, (I), (hkl)] are: 8.676, (80), (200); 4.654, (50), (4̅01); 3.870, (40), (2̅11); 3.394, (50), (113); 3.148, (40b), (6̅02); 2.892, (50), (6̅00); 2.724, (100), (7̅03); 2.185, (50), (3̅19). The formula shows a sulphur excess which may correspond to S-S bonding (persulphide). The new sulphosalt is a late phase in the crystallization sequence, and was formed after orpiment, contemporaneously with quartz II, at a temperature between 157 and 193°C. The name honours Dr Farahnaz Daliran (University of Karlsruhe, Germany) in recognition of her outstanding contributions to research on ore deposits, especially Au, Zn and Fe, in Iran.

Coiraite, (Pb,Sn2+)12.5As3Fe2+\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{Sn}_{5}^{4+}\) \end{document}S28:a franckeite-type new mineral species from Jujuy Province, NW Argentina

Abstract Coiraite, ideally (Pb,Sn2+)12.5As3Fe2+Sn4+5S28, occurs as an economically important tin ore in the large Ag-Sn-Zn polymetallic Pirquitas deposit, Jujuy Province, NW-Argentina. The new mineral species is the As derivative of franckeite and belongs to the cylindrite group of complex Pb sulphosalts with incommensurate composite-layered structures. It is a primary mineral, frequently found in colloform textures, and formed from hydrothermal solutions at low temperature. Associated minerals are franckeite, cylindrite, pyrite-marcasite, as well as minor amounts of hocartite, Ag-rich rhodostannite, arsenopyrite and galena. Laminae of coiraite consist of extremely thin bent platy crystals up to 50 μm long. Electron microprobe analysis (n = 31) gave an empirical formula Pb11.21As2.99Ag0.13Fe1.10Sn6.13S28.0, close to the ideal formula (Pb11.3S2+1.2)∑=12.5As3Fe2+Sn4+5S28. Coiraite has two monoclinic sub-cells, Q (pseudotetragonal) and H (pseudohexagonal). Q: a 5.84(1) Å, b 5.86(1) Å, c 17.32(1) Å, β 94.14(1)°, V 590.05(3) Å3, Z = 4, a:b:c = 0.997:1:2.955; 77 (orthogonal setting): a 6.28(1) Å, b 3.66(1) Å, c 17.33(1) Å, β 91.46(1)°, V 398.01(6) Å3, Z = 2, a:b:c = 1.716:1:4.735. The strongest Debye-Scherrer camera X-ray powder-diffraction lines [d in Å, (I), (hkl)] are: 5.78, (20), (Q and H 003); 4.34, (40), (Q 004); 3.46, (30), (Q and H 005); 3.339, (20), (Q 104); 2.876, (100), (Q and H 006); 2.068, (60), (Q 220).

Occurrence and paragenesis of tellurium in mineral deposits of Argentina

The occurrence of Te-bearing species in different deposit types of Argentina is reviewed. Tellurides with Au and/or Ag are especially abundant in epithermal environments of the high-and low-sulphidation states whereas those with Ag and Sn may prevail in Ag-Sn deposits. In very few cases (La Mejicana, Famatina; Farallon Negro) Au- and/or Ag-bearing tellurides contribute to the grade of these elements in the ore and thus are of economic importance. A great part of the deposits which contain tellurides is structurally controlled and genetically related with the Miocene to Pliocene volcanism.

Coiraite, (Pb,Sn2+)12.5As3Fe2+S28:a franckeite-type new mineral species from Jujuy Province, NW Argentina

Abstract Coiraite, ideally (Pb,Sn2+)12.5As3Fe2+Sn4+5S28, occurs as an economically important tin ore in the large Ag-Sn-Zn polymetallic Pirquitas deposit, Jujuy Province, NW-Argentina. The new mineral species is the As derivative of franckeite and belongs to the cylindrite group of complex Pb sulphosalts with incommensurate composite-layered structures. It is a primary mineral, frequently found in colloform textures, and formed from hydrothermal solutions at low temperature. Associated minerals are franckeite, cylindrite, pyrite-marcasite, as well as minor amounts of hocartite, Ag-rich rhodostannite, arsenopyrite and galena. Laminae of coiraite consist of extremely thin bent platy crystals up to 50 μm long. Electron microprobe analysis (n = 31) gave an empirical formula Pb11.21As2.99Ag0.13Fe1.10Sn6.13S28.0, close to the ideal formula (Pb11.3S2+1.2)∑=12.5As3Fe2+Sn4+5S28. Coiraite has two monoclinic sub-cells, Q (pseudotetragonal) and H (pseudohexagonal). Q: a 5.84(1) Å, b 5.86(1) Å, c 17.32(1) Å, β 94.14(1)°, V 590.05(3) Å3, Z = 4, a:b:c = 0.997:1:2.955; 77 (orthogonal setting): a 6.28(1) Å, b 3.66(1) Å, c 17.33(1) Å, β 91.46(1)°, V 398.01(6) Å3, Z = 2, a:b:c = 1.716:1:4.735. The strongest Debye-Scherrer camera X-ray powder-diffraction lines [d in Å, (I), (hkl)] are: 5.78, (20), (Q and H 003); 4.34, (40), (Q 004); 3.46, (30), (Q and H 005); 3.339, (20), (Q 104); 2.876, (100), (Q and H 006); 2.068, (60), (Q 220).

Coiraite, (Pb,Sn 2+ ) 12.5 As 3 Fe 2+ Sn 4+ 5 S 28 : a franckeite-type new mineral species from Jujuy Province, NW Argentina

Abstract Coiraite, ideally (Pb,Sn2+)12.5As3Fe2+Sn4+5S28, occurs as an economically important tin ore in the large Ag-Sn-Zn polymetallic Pirquitas deposit, Jujuy Province, NW-Argentina. The new mineral species is the As derivative of franckeite and belongs to the cylindrite group of complex Pb sulphosalts with incommensurate composite-layered structures. It is a primary mineral, frequently found in colloform textures, and formed from hydrothermal solutions at low temperature. Associated minerals are franckeite, cylindrite, pyrite-marcasite, as well as minor amounts of hocartite, Ag-rich rhodostannite, arsenopyrite and galena. Laminae of coiraite consist of extremely thin bent platy crystals up to 50 μm long. Electron microprobe analysis (n = 31) gave an empirical formula Pb11.21As2.99Ag0.13Fe1.10Sn6.13S28.0, close to the ideal formula (Pb11.3S2+1.2)∑=12.5As3Fe2+Sn4+5S28. Coiraite has two monoclinic sub-cells, Q (pseudotetragonal) and H (pseudohexagonal). Q: a 5.84(1) Å, b 5.86(1) Å, c 17.32(1) Å, β 94.14(1)°, V 590.05(3) Å3, Z = 4, a:b:c = 0.997:1:2.955; 77 (orthogonal setting): a 6.28(1) Å, b 3.66(1) Å, c 17.33(1) Å, β 91.46(1)°, V 398.01(6) Å3, Z = 2, a:b:c = 1.716:1:4.735. The strongest Debye-Scherrer camera X-ray powder-diffraction lines [d in Å, (I), (hkl)] are: 5.78, (20), (Q and H 003); 4.34, (40), (Q 004); 3.46, (30), (Q and H 005); 3.339, (20), (Q 104); 2.876, (100), (Q and H 006); 2.068, (60), (Q 220).