Lengenbach Quarry Research Articles

Tennantite-(Hg), Cu6(Cu4Hg2)As4S13, a new tetrahedrite-group mineral from the Lengenbach quarry, Binn, Switzerland

AbstractTennantite-(Hg), Cu6(Cu4Hg2)As4S13, was approved as a new mineral species (IMA2020-063) from the Lengenbach quarry, Imfeld, Binn Valley, Canton Valais, Switzerland. It was identified as an aggregate of black metallic tetrahedral crystals, less than 0.1 mm in size, intimately associated with sinnerite, and grown on realgar. In reflected light, tennantite-(Hg) is isotropic, grey in colour, with creamy tints. Minimum and maximum reflectance data for COM wavelengths in air are [λ (nm): R (%)]: 470: 29.1; 546: 29.1; 589: 28.5; 650: 27.7. Electron microprobe analysis gave (in wt.% – average of 7 spot analyses): Cu 32.57(42), Ag 6.38(19), Tl 0.29(14), Zn 0.04(5), Hg 17.94(2.27), Pb 0.70(51), As 17.83(61), Sb 0.34(8), S 24.10(41), total 100.19(1.04). The empirical formula of the sample studied, recalculated on the basis of ΣMe = 16 atoms per formula unit, is (Cu4.69Ag1.04Tl0.03)Σ5.76(Cu4.35Hg1.58Pb0.06Zn0.01)Σ6.00(As4.20Sb0.05)Σ4.25S13.26. Tennantite-(Hg) is cubic, I$\overline 4$3m, with a = 10.455(7) Å, V = 1143(2) Å3 and Z = 2. The crystal structure of tennantite-(Hg) has been refined by single-crystal X-ray diffraction data to a final R1 = 0.0897 on the basis of 214 unique reflections with Fo > 4σ(Fo) and 22 refined parameters. Tennantite-(Hg) is isotypic with other members of the tetrahedrite group. Mercury is hosted at the tetrahedrally coordinated M(1) site, in accord with the relatively long M(1)–S(1) distance (2.389 Å), similar to that observed in tetrahedrite-(Hg). Minor Ag is located at the triangularly-coordinated and split M(2) site. Other occurrences of tennantite-(Hg) are briefly reviewed and the Lengenbach finding is described within the framework of previous knowledge about the Hg mineralogy at this locality.

Lengenbachite from the Kochkovskoe Gold Deposit (Zabaykalsky Krai)

The article presents the analytical data on lengenbachite, a rare As–Pb sulfosalt, which was found in sulfde ores of the Kochkovskoe gold deposit in Zabaykalsky Krai. Until recent, lengenbahitе was found only in the Lengenbach quarry (Switzerland), Negus, Kohn (Canada) and Sherlovaya Gora (Zabaikalsky Krai) deposits. The mineral is identifed in two sulfde aggregates located in the low-Fe sphalerite of gold-quartz-carbonate-polymetallic stage. Aggregate 1 is composed of jordanite with lengenbachite inclusions (Ag4.89Cu1.25Pb18.68As12.46S39.00, on average) and galena, which is overgrown by arsenopyrite and Ag-bearing tennantite. Aggregate 2 consists of an jordanitе grain with lengen-bachite inclusions (Ag5.23Cu0.79Pb18.57As11.93S39.00 , on average). Figures 5. Tables 3. References 17.

The Lengenbach Quarry in Switzerland: Classic Locality for Rare Thallium Sulfosalts

The Lengenbach quarry is a world-famous mineral locality, especially known for its rare and well-crystallized Tl, Pb, Ag, and Cu bearing sulfosalts. As of June 2018, it is the type locality for 44 different mineral species, making it one of the most prolific localities worldwide. A total of 33 thallium mineral species have been identified, 23 of which are type minerals. A brief description of several thallium species of special interest follows a concise and general overview of the thallium mineralization.

Heptasartorite, Tl7Pb22As55 S108, enneasartorite, Tl6 Pb32 As70 S140 and hendekasartorite, Tl2Pb48As82 S172, three members of the anion-omission series of 'sartorites' from the Lengenbach quarry at Binntal, Wallis, Switzerland

Detailed electron-microprobe investigations and crystal-structure determinations established that ‘sartorite’ represents a group of distinct mineral species, each with unique chemistry and crystal structure. These manifest themselves as the 7-, 9- and 11-fold P 2 1 / c superstructures of the basic 4.2 A substructure. Heptasartorite is Tl 7 Pb 22 As 55 S 108 [based on 192 atoms per formula unit ( apfu ), 84Me + 108S] with a = 29.269(2), b = 7.8768(5), c = 20.128(2) A, β = 102.065(2)° and unit-cell volume V = 4537.8 A 3 ; enneasartorite is Tl 6 Pb 32 As 70 S 140 (based on 248 apfu , 108Me + 140S) with a = 37.612(6), b = 7.8777(12), c = 20.071(3) A, β = 101.930(2)° and V = 5818.6(15) A 3 ; hendekasartorite is Tl 2 Pb 48 As 82 S 172 (based on 304 apfu , 132Me + 172S) (empirical ΣMe = 132.48) with a = 31.806(5), b = 7.889(12), c = 28.556(4) A and β = 99.034(2)° with V = 7076.4(15) A 3 . Physical and optical properties (grey with metallic lustre, in polished section white with visible bireflectance, red internal reflections; reflectance curves span 28.7–42.5%; Mohs hardness 3–3½) of these phases are very similar so that chemical analysis and/or single-crystal X-ray diffraction is needed to distinguish them. A brief description of complicated As m S n crank-shaft chains in the walls of double-ribbons which form the As-based slabs of these structures is given. The three new mineral species differ in their structures by 4.2 A modular increments, not just by cation substitutions. They represent anion-omission derivatives of the ‘ideal’ PbAs 2 S 4 composition with an important role for thallium in charge compensation. The described minerals belong to the late sulfide phases in the Pb–Tl–Ag–As deposit of Lengenbach, Wallis, Switzerland.

Richardsollyite, TlPbAsS3, a new sulfosalt from the Lengenbach quarry, Binn Valley, Switzerland

The new mineral species richardsollyite, TlPbAsS 3 , was discovered in the Lengenbach quarry, Imfeld, Binn Valley, Canton Valais, Switzerland, intimately associated with hutchinsonite and baryte. It occurs as grey-black crystals, up to 750 μm, with a metallic lustre. Under the reflected-light microscope, richardsollyite is grey, with bright-red internal reflections; anisotropy is distinct, with greyish-white to bluish rotation tints. Reflectance values for the four COM wavelengths are [ R min , R max (%), (λ)]: 27.9, 29.8 (471.1 nm); 27.8, 31.0 (548.3 nm); 27.3, 30.8 (586.6 nm); and 27.0, 30.5 (652.3 nm). Electron microprobe analysis gave (in wt%): Tl 34.72(51), Pb 35.45(20), As 12.80(14), Sb 0.04(1), S 16.22(13), total 99.24(47). On the basis of 6 atoms per formula unit, the chemical formula is Tl 1.001 Pb 1.008 (As 1.007 Sb 0.002 ) Σ1.009 S 2.982 . The main diffraction lines [ d in A (intensity) hkl ] are: 4.23 (80) 1 ¯ 0 2 ; 3.875 (70) 2 ¯ 1 1 ; 3.762 (100) 2 1 0, 1 2 0; 3.278 (70) 1 0 2; 2.931 (70) 0 2 2; 2.714 (70) 1 ¯ 1 3 ; and 2.622 (80) 3 ¯ 1 2 . Richardsollyite is monoclinic, space group P 2 1 / c , with a = 8.8925(2), b = 8.4154(2), c = 8.5754(2) A, β = 108.665(3)°, V = 607.98(3) A 3 , Z = 4. The crystal structure was solved and refined to R 1 = 0.0242 on the basis of 1590 reflections with F o > 4σ( F o ). It can be described as formed by (1 0 0) [Pb (AsS 3 )] − layers sandwiching Tl + cations, and is isostructural with synthetic ABCX 3 ( A = K, Rb, Cs; B = Eu, Ba; C = As, Sb; X = S, Se) compounds. The new mineral is named after Richard Harrison Solly (1851–1925) for his outstanding contribution to the knowledge of the Lengenbach mineralogy during the first flourishing period of Lengenbach investigations, at the beginning of the 20th Century.

Ferrostalderite, CuFe2TlAs2S6, a new mineral from Lengenbach, Switzerland: occurrence, crystal structure, and emphasis on the role of iron in sulfosalts

AbstractThe new mineral species ferrostalderite, CuFe2TlAs2S6, was discovered in the Lengenbach quarry, Binn Valley, Wallis, Switzerland. It occurs as minute, metallic, black, equant to prismatic crystals, up to 50 mu;m, associated with dolomite, realgar, baumhauerite (?) and pyrite. Minimum and maximum reflectance data for COM wavelengths in air are [λ (nm): R (%)]: 471.1: 24.2/25.4; 548.3: 23.7/24.7; 586.6: 22.9/23.8; 652.3: 21.0/22.0. Electron microprobe analyses give (wt.%): Cu 6.24(25), Ag 4.18(9), Fe 9.95(83), Zn 4.46(91), Hg 1.22(26), Tl 26.86(62), As 19.05(18), Sb 0.63(6),S 25.39(47), total 97.98(72). On the basis of 12 atoms per formula unit, the chemical formula of ferrostalderite is Cu0.75(2)Ag0.30(1)Fe1.36(10)Zn0.52(11)Hg0.05(1)Tl1.00(1)[As1.94(4)Sb0.04(1)]∑1.98(4)S6.04(4). The new mineral is tetragonal, space group I4̄2 m, with a = 9.8786(5), c = 10.8489(8) Å, V = 1058.71(11) Å3, Z = 4. The main diffraction lines of the calculated powder diagram are [d (in Å), intensity, hkl]: 4.092, 70, 211; 3.493, 23, 220; 3.396, 35, 103; 3.124, 17, 310; 2.937, 100, 222; 2.656, 19, 321; 2.470, 19, 400; 2.435, 33, 303. The crystal structure of ferrostalderite has been refined by Xray single-crystal data to a final R1= 0.050, on the basis of 1169 reflections with F0 > 4σ(F0). It shows a three dimensional framework of (Cu,Fe)-centred tetrahedra (1M1 + 2 M2), with channels parallel to [001] hosting disymmetric TlS6and (As,Sb)S3 polyhedra. Ferrostalderite is derived from its isotype stalderiteM1CuM2Zn2TlAs2S6through the homovalent substitution M2Zn2+ → M2Fe2+. The ideal crystal-chemical formula of ferrostalderite isM1CuM2Fe2TlAs2S6.

Ralphcannonite, AgZn2TlAs2S6, a new mineral of the routhierite isotypic series from Lengenbach, Binn Valley, Switzerland

AbstractThe new mineral species ralphcannonite, AgZn2TlAs2S6, 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 dufrénoysite, 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 Ag0.63(2)Cu0.25(2)Zn1.35(5)Fe0.47(1)Hg0.32(2)Tl0.97(3)[As1.97(6)Sb0.01(1)]Σ1.98(5)S6.03(8). The new mineral is tetragonal, space group I42m, with a = 9.861 (2), c = 11.125(3) Å, V = 1081.8(4) Å3, Z = 4. The main diffraction lines of the calculated powder diagram are [d (in Å), 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 R1 = 0.030, on the basis of 140 observed reflections [Fo > 4σ(Fo)]. It shows a three dimensional framework of (Ag,Zn)-centred tetrahedra (1 M1 + 2 M2), with channels parallel to [001] hosting TlS6 and (As,Sb)S3 disymmetric polyhedra. Ralphcannonite is derived from its isotype routhierite M1CuM2Hg2TlAs2S6 through the double heterovalent substitution M1Cu+ + M2Hg2+ → M1Zn2+ + M2Ag+. This substitution obeys a steric constraint, with Ag+, the largest cation relative to Zn2+ and Cu+, entering the largest M2 site, as observed in arsiccioite. The ideal crystal-chemical formula of ralphcannonite is M1ZnM2(Zn0.5Ag0.5)2TlAs2S6.

Eckerite, Ag2CuAsS3, a new Cu-bearing sulfosalt from Lengenbach quarry, Binn valley, Switzerland: description and crystal structure

AbstractEckerite, ideally Ag2CuAsS3, is a new mineral from the Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs as very rare euhedral crystals up to 300 μm across associated with realgar, sinnerite, hatchite, trechmannite and yellow, fibrous smithite. In thick section eckerite is opaque with a metallic lustre and shows a dark orange-red streak. It is brittle; the Vickers hardness (VHN25) is 70 kg/mm2(range: 64–78) (Mohs hardness of ∼2½–3). In reflected light, eckerite is moderately bireflectant and weakly pleochroic from light grey to a slightly bluish grey. Internal reflections are absent. Under crossed nicols, it is weakly anisotropic with greyish to light blue rotation tints. Reflectance percentages forRminandRmaxare 27.6, 31.7 (471.1 nm), 22.8, 26.1 (548.3 nm), 21.5, 24.5 (586.6 nm) and 19.4, 22.3 (652.3 nm), respectively.Eckerite is monoclinic, space groupC2/c, witha= 11.8643(3),b= 6.2338(1),c= 16.6785(4) Å, β = 110.842(3)°,V= 1152.81(5) Å3,Z= 8. The crystal structure [R1= 0.0769 for 1606 reflections withFo> 4σ(Fo)] is topologically identical to that of xanthoconite and pyrostilpnite. In the structure, AsS3 pyramids are joined by AgS3triangles to form double sheets parallel to (001); the sheets are linked by Cu(Ag) atoms in a quasi-tetrahedral coordination. Among the three metals sites, Ag2 is dominated by Cu. The mean metal–S distances reflect well the Ag ↔ Cu substitution occurring at this site.The eight strongest powder X-ray diffraction lines [din Å (I/I0) (hkl)] are: 3.336 (70) (312); 2.941 (100) (314,114); 2.776 (80) (400,206); 2.677 (40) (312); 2.134 (50) (421); 2.084 (40) (208,206); 2.076 (40) (420); 1.738 (40) (228,226). A mean of five electron microprobe analyses gave Ag 52.08(16), Cu 11.18(9), Pb 0.04(1), Sb 0.29(3), As 15.28(11), S 20.73(13), total 99.60 wt.%, corresponding, on the basis of a total of 7 atoms per formula unit, to Ag2.24Cu0.82As0.94Sb0.01S2.99. The new mineral has been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (2014–063) and named for Markus Ecker, a well known mineral expert on the Lengenbach minerals for more than 25 years.

Tl-bearing sulfosalt from the Lengenbach quarry, Binn Valley, Switzerland: Philrothite, TlAs3S5

AbstractPhilrothite, ideally TlAs3S5, is a new mineral from the Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs as very rare crystals up to 200 mm across on realgar associated with smithite, rutile and sartorite. Philrothite is opaque with a metallic lustre and shows a dark brown streak. It is brittle; the Vickers hardness (VHN25) is 128 kg/mm2(range: 120–137) (Mohs hardness of 3–3½). In reflected light philrothite is moderately bireflectant and weakly pleochroic from dark grey to light grey. Under crossed polars it is anisotropic with grey to bluish rotation tints. Internal reflections are absent. Reflectance percentages for the four COM wavelengths (RminandRmax) are: 26.5, 28.8 (471.1 nm), 25.4, 27.2 (548.3 nm), 24.6, 26.3 (586.6 nm) and 24.0, 25.1 (652.3 nm), respectively.Philrothite is monoclinic, space groupP21/c, witha= 8.013(2),b= 24.829(4),c= 11.762(3) Å,β= 132.84(2)°,V= 1715.9(7) Å3,Z= 8. It represents theN= 4 homologue of the sartorite homologous series. In the crystal structure [R1= 0.098 for 1217 reflections withI> 2σ(I)], Tl assumes tricapped prismatic sites alternating to form columns perpendicular to the b axis. Between the zigzag walls of Tl coordination prisms, coordination pyramids of As(Sb) form diagonally-oriented double layers separated by broader interspaces which house the lone electron pairs of these elements.The eight strongest calculated powder-diffraction lines [din Å(I/I0) (hkl)] are: 12.4145 (52) (020); 3.6768 (100) (61); 3.4535 (45) (131); 3.0150 (46) (53); 2.8941 (52) (81); 2.7685 (76) (230); 2.7642 (77) (34); 2.3239 (52) (092). A mean of five electron microprobe analyses gave Tl 26.28(12), Pb 6.69(8), Ag 2.50(4), Cu 0.04(2), Hg 0.07(2), As 32.50(13), Sb 3.15(3), S 26.35(10), total 97.58 wt.%, corresponding, on the basis of a total of nine atoms, to (Tl0.789Pb0.198)∑=0.987(As2.662Sb0.159Ag0.142Cu0.004Hg0.002)∑=2.969S5.044. The new mineral has been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (2013-066) and named for Philippe Roth (b. 1963), geophysicist and well known mineral expert on the Lengenbach minerals for more than 25 years.

Dervillite, Ag2AsS2, from Lengenbach quarry, Binn valley, Switzerland: occurrence and crystal structure

AbstractDervillite, As2AsS2, has been found in a sample from the Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs as very rare crystals up to 200 μm across on jordanite. Dervillite is opaque with a metallic lustre and shows a dark brown streak. The structure is monoclinic, space groupPc, witha= 9.6155(7),b= 12.9331(8),c= 6.8616(5) A ˚ ,b= 99.352(8)º,V= 842.0(1) Å3andZ= 8. In the crystal structure [R1= 0.060 for 2370 reflections withI> 2σ(I)], silver adopts various coordinations extending from quasi linear to quasi tetrahedral whereas arsenic forms very peculiar crystal-chemical environments, such as As(S2As) and As(S2AsAg). Such metalloid–metalloid or metal–metalloid bonds account for the apparent charge imbalance observed in the chemical formula.

SINNERITE, Cu6As4S9, FROM THE LENGENBACH QUARRY, BINN VALLEY, SWITZERLAND: DESCRIPTION AND RE-INVESTIGATION OF THE CRYSTAL STRUCTURE

We have characterized the crystal structure of sinnerite, Cu 6 As 4 S 9 , a rare sulfosalt mineral from the ores of the Lengenbach quarry, Binn Valley, Canton Valais, Switzerland, by single-crystal X-ray diffraction and chemical analysis. We found sinnerite to be structurally identical to synthetic Cu 6 As 4 S 9 . It is triclinic, space group P 1, with cell parameters: a 9.103(2), b 9.860(3), c 9.111(2) A, α 90.27(2), β 109.53(2), γ 107.58(2)°, V 729.6(4) A 3 , and Z = 2. Semi-quantitative SEM-EDS analyses confirmed the Cu 6 As 4 S 9 stoichiometry. The crystal structure of an untwinned crystal has been refined to R 1 = 5.45%. It consists of a sphalerite substructure with 2/5 of the tetrahedra replaced by AsS 3 pyramids; four pyramids form As 4 S 12 clusters around the vacant anion positions of the sphalerite archetype. These pyramids are linked into twisted and branched chain-like structures with compositions As 3 S 7 and As 5 S 11 . The chains are linked by CuS 4 tetrahedra. Packing of these chains results in the OD (order-disorder) character of the sinnerite structure.

Raberite, Tl5Ag4As6SbS15, a new Tl-bearing sulfosalt from Lengenbach quarry, Binn valley, Switzerland: description and crystal structure

AbstractRaberite, ideally Tl5Ag4As6SbS15, is a new mineral from Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs very rarely as euhedral crystals up to 150 m m across associated with yellow needle-like smithite, realgar, hatchite and probable trechmannite, edenharterite, jentschite and two unidentified sulfosalts. Raberite is opaque with a metallic lustre and has a dark brown–red streak. It is brittle with a Vickers hardness (VHN10) of 52 kg mm–2 (range 50–55) corresponding to a Mohs hardness of 2½–3. In reflected light raberite is moderately bireflectant and very weakly pleochroic from light grey to a slightly greenish grey. It is very weakly anisotropic with greyish to light blue rotation tints between crossed polars. Internal reflections are absent. Reflectance percentages for the four COM wavelengths [listed as Rmin, Rmax, (λ)] are 30.6, 31.8 (471.1 nm), 28.1, 29.3 (548.3 nm), 27.1, 28.0 (586.6 nm), and 25.8, 26.9 (652.3 nm).Raberite is triclinic, space group P1, with a = 8.920(1), b = 9.429(1), c = 20.062(3) Å, α = 79.66(1), β = 88.84(1), γ = 62.72(1)º, V = 1471.6(4) Å3 and Z = 2. The crystal structure [R1 = 0.0827 for 2110 reflections with I > 2σ(I)] consists of columns of nine-coordinate Tl atoms forming irregular polyhedra extending along [001] and forming sheets parallel to (010). The columns are decorated by cornersharing MS3 pyramids (M = As, Sb) and linked by AgS3 triangles. Of the seven M positions, one is dominated by Sb and the others by As; the mean M-S bond distances reflect As ↔ Sb substitution at these sites.The eight strongest lines in the powder diffraction pattern [dcalc in Å (I) (hkl)] are: 3.580 (100) (13); 3.506 (58) (23); 3.281 (73) (006); 3.017 (54) (3); 3.001 (98) (133); 2.657 (51) (226); 2.636 (46) (300); 2.591 (57) (330). A mean of 9 electron microprobe analyses gave Tl 39.55(13), Ag 18.42(8), Cu 0.06(2), As 17.08(7), Sb 5.61(6), S 19.15(11); total 99.87 wt.%, which corresponds to Tl4.85Ag4.28Cu0.02As5.72Sb1.16S14.97 with 31 atoms per formula unit. The new mineral has been approved by the IMA-CNMNC Commission (IMA 2012-017) and is named for Thomas Raber, an expert on Lengenbach minerals.

Debattistiite, Ag9Hg0.5As6S12Te2, a new Te-bearing sulfosalt from Lengenbach quarry, Binn valley, Switzerland: description and crystal structure

AbstractDebattistiite, ideally Ag9Hg0.5As6S12Te2, is a new mineral (IMA-CNMNC 2011-098) from the Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs as very rare tabular euhedral crystals up to 150 μm across in cavities in dolomitic marble, associated with realgar, rutile, trechmannite and hutchinsonite. Debattistiite is opaque with a metallic lustre and a grey streak. It is brittle; the Vickers hardness (VHN25) is 80 kg mm–2 (range: 65–94), corresponding to a Mohs hardness of 2–2½. In reflected light debattistiite is dark grey, highly bireflectant and weakly pleochroic from dark grey to a slightly greenish grey. Between crossed polars it is highly anisotropic with brownish to blue rotation tints. Internal reflections are absent. Reflectance percentages for the four COM wavelengths (Rmin and Rmax) are 27.2, 34.5 (471.1 nm), 25.5, 31.0 (548.3 nm), 22.9, 28.4 (586.6 nm), and 20.1, 25.2 (652.3 nm), respectively.Debattistiite is triclinic, space group P1, with a = 7.832(5), b = 8.606(4), c = 10.755(5) Å, α = 95.563(9), β = 95.880(5), γ = 116.79(4)°, V = 635.3(6) Å3 and Z = 1. The crystal structure [R1 = 0.0826 for 795 reflections with I > 2σ(I)] consists of corner-sharing AsS3 pyramids forming three-membered distorted rings linked by Ag atoms in triangular or tetrahedral coordination.The five strongest powder-diffraction lines [d in Å (I/I0) (hkl)] are as follows: 10.56 (6) (001); 3.301 (5) (12); 2.991 (4) (22); 2.742 (1) and 2.733 (10) (30). A mean of nine electron microprobe analyses gave: Ag 44.88, Hg 4.49, As 20.77, S 17.72, Te 11.82; total 99.68 wt.%, which corresponds to Ag9.02Hg0.49As6.012S11.98Te2.01, on the basis of 29.5 atoms. The new mineral is named for Luca De Battisti, a systematic mineralogist and expert on the minerals of Lengenbach quarry.

Te-RICH CANFIELDITE, Ag8Sn(S,Te)6, FROM THE LENGENBACH QUARRY, BINNTAL, CANTON VALAIS, SWITZERLAND: OCCURRENCE, DESCRIPTION AND CRYSTAL STRUCTURE

In order to evaluate the effects of Te-for-S substitution in the minerals of the argyrodite group, the crystal structure and chemical composition of a crystal of Te-rich canfieldite from the Lengenbach quarry, Binntal, Switzerland, was investigated. The unit-cell parameters are a 11.0003(6) A and V 1331.1(1) A 3 . The structure was solved and refined in the space group F 43 m to R 1 = 0.0308 for 194 independent reflections and 21 parameters. Quantitative analysis led to the chemical formula Ag 8.05 (Sn 1.03 Ge 0.01 ) ∑1.04 (S 3.95 Te 1.95 Se 0.01 ) ∑5.91 , ideally Ag 8 Sn(S,Te) 6 . The crystal structure of Te-rich canfieldite was found to be topologically identical to that of putzite, (Cu 4.7 Ag 3.3 )GeS 6 . Neglecting the short Ag-Ag contacts (due to disorder), the two Ag atoms in the structure can be considered as three-fold (Ag1) and four-fold (Ag2) coordinated. Tin adopts a regular tetrahedral coordination. The refinement of the site-occupancy factor indicates Te to be disordered over the three anion positions ( i.e., X 1, X 2, and X 3), with a preference for the X 1 site.

Ein Vorkommen von Lorandit (T1AsS 2) in der Schweiz

A new find of the thallium-arsenic-sulphosalt mineral lorandite in the Triassic dolomite of the famous Lengenbach quarry in Binnatal, Ct. Wallis (Switzerland) is described. Herewith the Lengenbach is, up to now, only the third locality, where lorandite has been found at all. The d-values for X-ray powder pattern, morphological data, and a microprobe analysis are given. Reflection percentage (for green light of 5300 A) is 32.6%, Vickers hardness number (with load of 30 g) is 38.9. Relations to the different thallium-sulphosalts of the Lengenbach are discussed.

Ilmenite from the dolomite at Binn, Switzerland

As is well known, the dolomite of the Lengenbach quarry is rich in pyrites and has some rutile.; the crystals of the latter being very small and somewhat infrequent. It seems therefore strange that the presence of hematite or ilmenite has not hitherto been recorded. This last summer I obtained a specimen which showed a minute black crystal with numerous faces, which I began examining under the impression that it was a sulpharsenite.

Hatchite, a new (anorthic) mineral from the Binnenthal

Nearly ten years ago, in 1902, five small crystals were noticed by one of us on a crystal of a sulpharsenite of lead, probably rathite, which had been found in the Lengenbach quarry that summer. Although from their lead-grey colour they also appeared to belong to a sulpharsenite of lead, in habit and appearance they were unlike the crystals of any such species as yet known. The crystals were measured, and were shown at the anniversary meeting, of the Society, November 18, 1902, but the measurements were not published at the time in the expectation that further material would afterwards be found which would enable an analysis to be made and perhaps throw fresh light on the morphological characters of the crystals.

Description of large crystals of Seligmannite and Dufrenoysite

In the summer of 1906 some large crystals of seligmannite were found in an irregular, elongated cavity in the dolomite-rock of the Lengenbach quarry at Binn, Switzerland. Owing to their brittle nature many of them were broken when the rock was blasted, but I was in the quarry at the time and collected all the fragments. The largest crystal broke after it had been measured, and Dr. G. T. Prior's analysis II was made on portions of it, his other analysis, I, being made on measured crystal fragments found with the large crystal. The streak of the present crystals is black and inclined to purplish in colour, while that of the crystals first described by me was chocolate-coloured.

Red silver minerals from the Binnenthal, Switzerland

For many years past Mr. R. H. Solly has been accustomed to spend each succeeding summer in the quest of mineral specimens in the neighbourhood of the village of Binn, Switzerland, particularly of those occurring in the white crystalline dolomite of the Lengenbach quarry, and his patient energy has been rewarded by the discovery, not only of material which has thrown fresh light on previously known minerals, but also of specimens which on examination proved to represent species new to science. Especially important was the discovery in 1903 of small, and often minute, blood-red crystals which differed both in colour and in streak from realgar, a common mineral in the quarry.

Some new minerals from the Binnenthal, Switzerland

A preliminary notice of this new mineral, named in honour of Dr. Arthur Hutchinson, Demonstrator of Mineralogy in the University of Cambridge, was read before the Cambridge Philosophical Society in October, 1903. The material was first found, in the white crystalline dolomite of the Lengenbach quarry, during my visit to the Binnenthal in the summer of 1903. More material was received in November of the same year, and a further supply was obtained in 1904.