Routhierite

Abstract: Routhierite, ~ (Cu 0.8 Ag 0.2 )Hg 2 Tl(As 1.4 Sb 0.6 ) ∑=2 S 6 , was identified in the baryte + pyrite + iron oxide ore from Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. Routhierite occurs as anhedral grains up to 0.5 mm in size forming veinlets embedded in pyrite-rich dolostones, in association with aktashite, baryte, boscardinite, cymrite, protochabourneite, pyrite, realgar, Hg-rich sphalerite, and stibnite. Rarely, euhedral crystals of routhierite were also observed in quartz+baryte+dolomite veins, with boscardinite, Hg-rich oversubstituted andorite, realgar, sphalerite, and Hg-rich tetrahedrite. Electron-microprobe data give (in wt%): Cu 4.79(7), Ag 2.00(5), Fe 0.12(1), Hg 37.31(23), Zn 0.98(1), Cd 0.11(7), Tl 19.19(16), As 9.96(31), Sb 7.16(35), S 18.86(7), Cl 0.05(1), total 100.53(18). The structural formula, based on (S + Cl) = 6 at., is (Cu 0.77 Ag 0.19 Fe 0.02 ) ∑=0.98 (Hg 1.89 Zn 0.15 Cd 0.01 ) ∑=2.05 Tl 0.96 (As 1.35 Sb 0.60 ) ∑=1.95 (S 5.99 Cl 0.01 ) ∑=6.00 . The crystal structure of routhierite from Monte Arsiccio mine was refined to R 1 = 0.030 in the I -42 m space group, with unit-cell parameters a 9.9780(5), c 11.3764(7) A, V 1132.6(1) A 3 . In the crystal structure of routhierite, (Cu,Ag)S 4 and (Hg,Zn)S 4 tetrahedra share corners to form a framework with channels parallel to [001] hosting TlS 6 and (As,Sb)S 3 polyhedra. The relatively short Tl–Tl distance (3.33 A) could indicate Tl–Tl interaction. Chemical and crystallographic data indicate the Sb-rich nature of routhierite from Monte Arsiccio mine. The Sb/(Sb + As) atomic ratio is 0.31, to be compared with 0.11–0.12 for routhierite from the type locality of Jas Roux, France. The Sb enrichment of this new occurrence is in agreement with the usual predominance of antimony in sulfosalts from hydrothermal ores of Apuan Alps.

Abstract: Tsygankoite, ideally Mn8Tl8Hg2(Sb21Pb2Tl)Σ24S48, is a new sulfosalt discovered at the Vorontsovskoe gold deposit, Northern Urals, Russia. It occurs as lath-like elongated crystals up to 0.2 mm embedded in calcite–dolomite–clinochlore matrix. The associated minerals also include aktashite, alabandite, arsenopyrite, barite, cinnabar, fluorapatite, orpiment, pyrite, realgar, routhierite, sphalerite, tilasite, and titanite. The new mineral is non-fluorescent, black, and opaque with a metallic lustre and black streak. It is brittle with an uneven fracture and no obvious parting and cleavage. Its Vickers hardness (VHN10) is 144 kg/mm2 (range 131–167 kg/mm2) and its calculated density is 5.450 g cm. In reflected light, tsygankoite is white; between crossed polars it is dark grey to black. It is strongly anisotropic: rotation tints vary from light grey to dark grey to black. Pleochroism and internal reflections are not observed. The chemical composition of tsygankoite (wt %, electron-microprobe data) is: Mn 6.29, Hg 5.42, Tl 26.05, Pb 5.84, As 3.39, Sb 30.89, S 21.87, total 99.75. The empirical formula, calculated on the basis of 90 atoms pfu, is: Mn8.06Tl8.00Hg1.90(Sb17.87As3.19Pb1.99Tl0.97)Σ24.02S48.03. Tsygankoite is monoclinic, space group C2/m, a = 21.362(4) A, b = 3.8579(10) A, c = 27.135(4) A, β = 106.944(14)°, V = 2139.19(17) A3 and Z = 1. The five strongest diffraction peaks from X-ray powder pattern (listed as (d,A(I)(hkl)) are: 3.587(100)(112), 3.353(70)(−114), 3.204(88)(405), 2.841(72)(−513), and 2.786(99)(−514). The crystal structure of tsygankoite was refined from single-crystal X-ray diffraction data to R = 0.0607 and consists of an alternation of two thick layer-like arrays, one based on PbS-archetype and the second on SnS-archetype. Tsygankoite has been approved by the IMA-CNMNC under the number 2017-088. It is named for Mikhail V. Tsyganko, a mineral collector from Severouralsk, Northern Urals, Russia, who collected the samples where the new mineral was discovered.

Abstract: The new mineral species ralphcannonite, AgZn 2 TlAs 2 S 6 , was discovered in the Lengenbach quarry, Binn Valley, Wallis, Switzerland. It occurs as metallic black equant, isometric to prismatic crystals, up to 50 μm, associated with dufrenoysite, hatchite, realgar and baryte. Minimum and maximum reflectance data for COM wavelengths in air are [λ (nm): R (%)]: 471.1: 25.8/27.1; 548.3: 25.2/26.6; 586.6: 24.6/25.8; 652.3: 23.9/24.8. Electron microprobe analyses give (wt.%): Cu 2.01(6), Ag 8.50(16), Zn 10.94(20), Fe 3.25(8), Hg 7.92(12), Tl 24.58(26), As 18.36(19), Sb 0.17(4), S 24.03(21), total 99.76(71). On the basis of 12 atoms per formula unit, the chemical formula of ralphcannonite is Ag 0.63(2) Cu 0.25(2) Zn 1.35(5) Fe 0.47(1) Hg 0.32(2) Tl 0.97(3) [As 1.97(6) Sb 0.01(1) ] Σ1.98(5) S 6.03(8) . The new mineral is tetragonal, space group I 4I2 m , with a = 9.861 (2), c = 11.125(3) A, V = 1081.8(4) A 3 , Z = 4. The main diffraction lines of the calculated powder diagram are [ d (in A), intensity, hkl ]: 4.100, 85, 211; 3.471, 40, 103; 2.954, 100, 222; 2.465, 24, 400; 2.460, 39, 303. The crystal structure of ralphcannonite has been refined by X-ray single-crystal data to a final R 1 = 0.030, on the basis of 140 observed reflections [ F o > 4σ( F o )]. It shows a three dimensional framework of (Ag,Zn)-centred tetrahedra (1 M 1 + 2 M 2), with channels parallel to [001] hosting TlS 6 and (As,Sb)S 3 disymmetric polyhedra. Ralphcannonite is derived from its isotype routhierite M 1 Cu M 2 Hg 2 TlAs 2 S 6 through the double heterovalent substitution M 1 Cu + + M 2 Hg 2+ → M 1 Zn 2+ + M 2 Ag + . This substitution obeys a steric constraint, with Ag + , the largest cation relative to Zn 2+ and Cu + , entering the largest M 2 site, as observed in arsiccioite. The ideal crystal-chemical formula of ralphcannonite is M 1 Zn M 2 (Zn 0.5 Ag 0.5 ) 2 TlAs 2 S 6 .

Abstract: Luboržakite, 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, chabourneite, coloradoite, clerite, ecrinsite, gold, routhierite, sphalerite and twinnite. Luboržakite 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, luboržakite is tin-white, weakly anisotropic with rotation tints varying from dark grey to grey. The chemical composition of luboržakite 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) A, β = 94.190(4)°, V = 761.57(6) A3 and Z = 4. The crystal structure of luboržakite was solved from the single-crystal X-ray diffraction data to R = 0.0383 for 712 observed reflections with I > 3σ(I). Luboržakite is a new member of the heterochemical isostructural series of ‘unit-cell twinned’ structures, named the pavonite series. The new mineral honours Lubor Žak, a prominent Czech crystallographer and the professor of the Charles University in Prague, Czech Republic.