ALBERT

Description: 〈span〉Lavinskyite-1〈span〉M〈/span〉, a monoclinic MDO (Maximum Degree of Order) polytype related to the orthorhombic MDO polytype lavinskyite-2〈span〉O〈/span〉 (formerly lavinskyite, now redefined), was identified in samples from the Cerchiara manganese mine (Liguria, Italy). Both polytypes have the same ideal chemical formula, K(LiCu)Cu〈sub〉6〈/sub〉(Si〈sub〉4〈/sub〉O〈sub〉11〈/sub〉)〈sub〉2〈/sub〉(OH)〈sub〉4〈/sub〉. Lavinskyite-1〈span〉M〈/span〉 was originally approved as “liguriaite”, but was subsequently redefined as lavinskyite-1〈span〉M〈/span〉 (IMA proposal 16-E).Lavinskyite-1〈span〉M〈/span〉 occurs as blue, micaceous aggregates embedded in calcite-filled microfractures and veinlets, where it is associated with calcite, quartz, norrishite and “schefferite” (a Mn-bearing variety of diopside). Lavinskyite-1〈span〉M〈/span〉 is translucent to transparent, bluish to pale blue in colour with a very pale blue to whitish streak and vitreous lustre; it is non-fluorescent. Individual, always indistinct platelets are up to ∼0.15 mm in length. The crystals are tabular (100) and elongate along [001]. Lavinskyite-1〈span〉M〈/span〉 is brittle with perfect cleavage parallel to {100}, and uneven fracture. The estimated Mohs hardness is ∼5. The calculated density is 3.613 g/cm〈sup〉3〈/sup〉 (for empirical formula). Optically, it is biaxial positive, with α = 1.674(2); β = 1.692(3) and γ = 1.730(3); 2〈span〉V〈/span〉〈sub〉γ〈/sub〉 is very large, ∼75° (est.), 2〈span〉V〈/span〉〈sub〉γ〈/sub〉 (calc.) = 70°. Pleochroism is moderate: 〈span〉X〈/span〉 (pale) blue, 〈span〉Y〈/span〉 pale blue and 〈span〉Z〈/span〉 pale blue with faint greenish tint; absorption 〈span〉X〈/span〉 ≥ 〈span〉Z〈/span〉 ≥ 〈span〉Y〈/span〉. Orientation: 〈span〉X〈/span〉 ^ 〈span〉a〈/span〉 ∼20° (probably in obtuse beta), 〈span〉Y〈/span〉 = 〈span〉b〈/span〉, 〈span〉Z〈/span〉 ∼ 〈span〉c〈/span〉; optical elongation is positive and the optical axis plane is parallel to (010). No dispersion was observed.Chemical analysis (quantitative SEM-EDS and LAICPMS) of two samples yielded the empirical formulae (based on 26 O atoms) (K〈sub〉1.08〈/sub〉)〈sub〉Σ1.08〈/sub〉(Li〈sub〉0.89〈/sub〉Mg〈sub〉0.36〈/sub〉Cu〈sub〉0.33〈/sub〉Na〈sub〉0.22〈/sub〉Mn〈sup〉2+〈/sup〉〈sub〉0.04〈/sub〉)〈sub〉Σ1.86­〈/sub〉Cu〈sub〉6.00〈/sub〉Si〈sub〉8.08〈/sub〉O〈sub〉22〈/sub〉(OH)〈sub〉4〈/sub〉 and (K〈sub〉1.08〈/sub〉)〈sub〉Σ1.08〈/sub〉(Li〈sub〉0.89〈/sub〉Cu〈sub〉0.35〈/sub〉Mg〈sub〉0.28〈/sub〉Na〈sub〉0.22〈/sub〉Mn〈sup〉2+〈/sup〉〈sub〉0.04〈/sub〉) 〈sub〉Σ1.78­〈/sub〉Cu〈sub〉6.00〈/sub〉Si〈sub〉8.12〈/sub〉O〈sub〉22〈/sub〉(OH)〈sub〉4〈/sub〉. Strongest lines in the X-ray powder diffraction pattern are [〈span〉d〈/span〉 in Å (〈span〉I〈/span〉〈sub〉calc〈/sub〉) 〈span〉hkl〈/span〉]): 10.216 (100) 100, 9.007 (20) 110, 4.934 (19) 210, 3.983 (19) 230, 3.353 (33) 310, 2.8693 (22) 241, 2.6155 (35) 161, 2.3719 (23) 20-2. The crystal structure has been solved, using single-crystal X-ray diffractometer data (〈span〉Rint〈/span〉 = 4.60%), by direct methods and refined in space group 〈span〉P〈/span〉2〈sub〉1〈/sub〉/〈span〉c〈/span〉 (no. 14) to 〈span〉R〈/span〉1 = 5.10% and 〈span〉wR〈/span〉2〈sub〉〈span〉all〈/span〉〈/sub〉 = 13.92% [1786 ‘observed’ reflections with 〈span〉F〈/span〉〈sub〉o〈/sub〉 〉 4σ(〈span〉F〈/span〉〈sub〉o〈/sub〉), 199 parameters]. Refined unit-cell parameters are: 〈span〉a〈/span〉 = 10.224(2), 〈span〉b〈/span〉 = 19.085(4), 〈span〉c〈/span〉 = 5.252(1) Å, β = 92.23(3)°, 〈span〉V〈/span〉 = 1024.0(4) Å〈sup〉3〈/sup〉 (〈span〉Z〈/span〉 = 2). The chemical composition and crystal structure are supported by micro-Raman spectra.Lavinskyite-1〈span〉M〈/span〉 has a sheet structure consisting of corrugated brucite-like (CuO〈sub〉2〈/sub〉)〈sub〉n〈/sub〉 layers with amphibole-type (SiO〈sub〉3〈/sub〉)〈sub〉n〈/sub〉 chains joined to both their upper and lower surfaces. Adjacent complex sheets are linked by [5]-coordinated Li atoms and Cu atoms in square coordination (nearly planar) and interlayer K atoms. Lavinskyite-1〈span〉M〈/span〉 is isostructural with a hypothetical monoclinic MDO polytype of plancheite, not yet found in nature, while lavinskyite-2〈span〉O〈/span〉 is isostructural with plancheite. It appears that a complex and delicate interplay between the Li:Cu and Cu:Mg ratios (lower in lavinskyite-1〈span〉M〈/span〉), along with an additional influence of impurity cations such as Na and different conditions of formation, results in a stabilisation of the 1〈span〉M〈/span〉 polytype. The origin of lavinskyite-1〈span〉M〈/span〉 can be related to a complex, multi-stage hydrothermal evolution of the primary Fe-Mn ore at Cerchiara, which experienced a diffuse alkali metasomatism under strongly oxidising conditions and produced mineral assemblages enriched in Na, K and Li, while providing also appreciable amounts of Ba, Sr, Ca and Cu.〈/span〉

Description: 〈span〉Vanderheydenite, Zn〈sub〉6〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉2〈/sub〉(SO〈sub〉4〈/sub〉)(OH)〈sub〉4〈/sub〉·7H〈sub〉2〈/sub〉O, is a new mineral from the Block 14 Opencut, Broken Hill, New South Wales, Australia. It occurs as aggregates of colourless crystals up to 0.5 mm across in voids of a sphalerite–galena matrix and is associated with anglesite, pyromorphite, sulfur, and liversidgeite. Crystals are pseudohexagonal blades up to 0.4 mm in length, flattened on {1 0 0} and exhibiting the forms {1 0 0}, {0 1 0}, and {0 2 1}. Cleavage was not observed. The Mohs hardness is estimated to be 3. The calculated density is 3.12 g/cm〈sup〉3〈/sup〉 from the empirical formula and 3.06 g/cm〈sup〉3〈/sup〉 from the ideal formula. The mineral is optically biaxial (–), with α = 1.565(4), β = 1.580(4) and γ = 1.582(4). The calculated 2〈span〉V〈/span〉 is 39.8°. Chemical analysis by electron microprobe gave ZnO 55.63, CuO 0.07, FeO 0.11, MnO 0.06, P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 14.18, As〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 4.33, SO〈sub〉3〈/sub〉 8.71, H〈sub〉2〈/sub〉O 18.31, total 101.40 wt%, with H〈sub〉2〈/sub〉O content derived from the refined crystal structure. The empirical formula calculated on the basis of 23 oxygen atoms is (Zn〈sub〉5.99〈/sub〉Cu〈sub〉0.01〈/sub〉Fe〈sub〉0.01〈/sub〉Mn〈sub〉0.01〈/sub〉)〈sub〉Σ6.02〈/sub〉[(PO〈sub〉4〈/sub〉)〈sub〉1.75〈/sub〉(AsO〈sub〉4〈/sub〉)〈sub〉0.33〈/sub〉]〈sub〉Σ2.08〈/sub〉(SO〈sub〉4〈/sub〉)〈sub〉0.95〈/sub〉(OH)〈sub〉3.91〈/sub〉·6.96H〈sub〉2〈/sub〉O. The mineral is monoclinic, 〈span〉P〈/span〉2〈sub〉1〈/sub〉/〈span〉n〈/span〉, with 〈span〉a〈/span〉 = 6.2040(12), 〈span〉b〈/span〉 = 19.619(4), 〈span〉c〈/span〉 = 7.7821(16) Å, β = 90.67(3)°, 〈span〉V〈/span〉 = 947.1(3) Å〈sup〉3〈/sup〉. The five strongest lines in the X-ray powder diffraction pattern are [〈span〉d〈/span〉(Å), (〈span〉I〈/span〉), (〈span〉hkl〈/span〉)]: 9.826 (57) (0 2 0), 7.296 (20) (0 1 1), 6.134 (1 0 0) (0 2 1), 3.368 (10) (0 3 2, 1 5 0), 3.069 (9) (2 1 0, 0 4 2). The crystal structure of vanderheydenite (〈span〉R〈/span〉1 = 0.0497 for 939 reflections with 〈span〉F〈/span〉〈sub〉o 〈/sub〉〉 4σ〈span〉F〈/span〉) contains chains of edge-sharing ZnO〈sub〉6〈/sub〉 octahedra parallel to 〈span〉a〈/span〉 that are linked by edge- and corner-sharing ZnO〈sub〉5〈/sub〉 trigonal bipyramids and 〈span〉T〈/span〉O〈sub〉4〈/sub〉 (〈span〉T〈/span〉 = P, As) tetrahedra forming zig-zag sheets parallel to {0 1 0}. Sheets are linked by half-occupied, distorted 〈span〉T〈/span〉O〈sub〉4〈/sub〉 (〈span〉T〈/span〉 = P, S) tetrahedra in the [0 1 1] direction. Interstitial channels extend parallel to the 〈span〉a〈/span〉-direction and are occupied by strongly to weakly hydrogen-bonded H〈sub〉2〈/sub〉O groups.〈/span〉

Description: Fluor-schorl, NaFe 2+ 3 Al 6 Si 6 O 18 (BO 3 ) 3 (OH) 3 F, is a new mineral species of the tourmaline supergroup from alluvial tin deposits near Steinberg, Zschorlau, Erzgebirge (Saxonian Ore Mountains), Saxony, Germany, and from pegmatites near Grasstein (area from Mittewald to Sachsenklemme), Trentino, South Tyrol, Italy. Fluor-schorl was formed as a pneumatolytic phase and in high-temperature hydrothermal veins in granitic pegmatites. Crystals are black (pale brownish to pale greyish-bluish, if 〈0.3 mm in diameter) with a bluish-white streak. Fluor-schorl is brittle and has a Mohs hardness of 7; it is non-fluorescent, has no observable parting and a poor/indistinct cleavage parallel to {0001}. It has a calculated density of ~3.23 g/cm 3 . In plane-polarized light, it is pleochroic, O = brown to grey-brown (Zschorlau), blue (Grasstein), E = pale grey-brown (Zschorlau), cream (Grasstein). Fluor-schorl is uniaxial negative, = 1.660(2)–1.661(2), = 1.636(2)–1.637(2). The mineral is rhombohedral, space group R 3 m, a = 16.005(2), c = 7.176(1) Å, V = 1591.9(4) Å 3 (Zschorlau), a = 15.995(1), c = 7.166(1) Å, V = 1587.7(9) Å 3 (Grasstein), Z = 3. The eight strongest observed X-ray diffraction lines in the powder pattern [ d in Å ( I ) hkl ] are: 2.584(100)(051), 3.469(99)(012), 2.959(83)(122), 2.044(80)(152), 4.234(40)(211), 4.005(39)(220), 6.382(37)(101), 1.454(36)(514) (Grasstein). Analyses by a combination of electron microprobe, secondary-ion mass spectrometry (SIMS), Mössbauer spectroscopic data and crystal-structure refinement result in the structural formulae X (Na 0.82 K 0.01 Ca 0.01 0.16 ) Y (Fe 2+ 2.30 Al 0.38 Mg 0.23 Li 0.03 Mn 2+ 0.02 Zn 0.01 0.03 ) 3.00 Z (Al 5.80 Fe 3+ 0.10 Ti 4+ 0.10 ) T (Si 5.81 Al 0.19 O 18 ) (BO 3 ) 3 V (OH) 3 W [F 0.66 (OH) 0.34 ] (Zschorlau) and X (Na 0.78 K 0.01 0.21 ) Y (Fe 2+ 1.89 Al 0.58 Fe 3+ 0.13 Mn 3+ 0.13 Ti 4+ 0.02 Mg 0.02 Zn 0.02 0.21 ) 3.00 Z (Al 5.74 Fe 3+ 0.26 ) T (Si 5.90 Al 0.10 O 18 ) (BO 3 ) 3 V (OH) 3 W [F 0.76 (OH) 0.24 ] (Grasstein). Several additional, newly confirmed occurrences of fluor-schorl are reported. Fluor-schorl, ideally NaFe 2+ 3 Al 6 Si 6 O 18 (BO 3 ) 3 (OH) 3 F, is related to end-member schorl by the substution F -〉 (OH). The chemical compositions and refined crystal structures of several schorl samples from cotype localities for schorl (alluvial tin deposits and tin mines in the Erzgebirge, including Zschorlau) are also reported. The unit-cell parameters of schorl from these localities are slightly variable, a = 15.98–15.99, c = 7.15–7.16 Å, corresponding to structural formulae ranging from ~ X (Na 0.5 0.5 ) Y (Fe 2+ 1.8 Al 0.9 Mg 0.2 0.1 ) Z (Al 5.8 Fe 3+ 0.1 Ti 4+ 0.1 ) T (Si 5.7 Al 0.3 O 18 ) (BO 3 ) 3 V (OH) 3 W [(OH) 0.9 F 0.1 ] to ~ X (Na 0.7 0.3 ) Y (Fe 2+ 2.1 Al 0.7 Mg 0.1 0.1 ) Z (Al 5.9 Fe 3+ 0.1 ) T (Si 5.8 Al 0.2 O 18 ) (BO 3 ) 3 V (OH) 3 W [(OH) 0.6 F 0.4 ]. The investigated tourmalines from the Erzgebirge show that there exists a complete fluor-schorl–schorl solid-solution series. For all studied tourmaline samples, a distinct inverse correlation was observed between the X –O2 distance (which reflects the mean ionic radius of the X -site occupants) and the F content ( r 2 = 0.92). A strong positive correlation was found to exist between the F content and the 〈 Y –O〉 distance ( r 2 = 0.93). This correlation indicates that Fe 2+ -rich tourmalines from the investigated localities clearly tend to have a F-rich or F-dominant composition. A further strong positive correlation ( r 2 = 0.82) exists between the refined F content and the Y–W (F,OH) distance, and the latter may be used to quickly estimate the F content.

Description: The crystal structures of the secondary ferric iron minerals kamarizaite, Fe 3 3+ (AsO 4 ) 2 (OH) 3 · 3H 2 O, and tinticite, Fe 3 3+ (PO 4 ) 2 (OH) 3 · 3H 2 O, for which highly contradictory data on crystal symmetry were reported, were studied by a combination of single-crystal X-ray diffraction and Rietveld refinement (supplemented by chemical analyses and thermogravimetry), using type material of both species and additional samples from several other localities, including the type localities. The previously unknown crystal structure of kamarizaite was determined from single-crystal intensity data (Mo K α, 293 K, R ( F ) = 2.91 %; all H atoms detected) using a sample from the Le Mazet vein, Échassières, Auvergne, France. The mineral is triclinic, space group $$P\overline{1}$$ (no. 2), with a = 7.671(2), b = 8.040(2), c = 10.180(2) Å, α = 68.31(3), β = 75.35(3), = 63.52(3)°, V = 519.3(2) Å 3 , Z = 2. Rietveld analyses of fine-grained kamarizaite collected underground at two different spots in Lavrion, Greece (Hilarion and Jean Baptiste areas) confirmed the structure model. Rietveld analyses of fine-grained tinticite from Tintic, Utah (USA), Bruguers (Spain) and Weckersdorf (Germany) demonstrate that kamarizaite and tinticite are triclinic and isotypic. A previously published structure model for tinticite, as well as the originally reported orthorhombic symmetry for kamarizaite, are shown to be incorrect. Refined unit-cell parameters of a cotype tinticite specimen from Tintic are: a = 7.647(1), b = 7.958(1), c = 9.987(1) Å, α = 67.90(1), β = 76.10(1), = 64.10(1)°, V = 504.4(2) Å 3 . Bruguers and Weckersdorf tinticite have very similar parameters. The common atomic arrangement is characterised by three unique, octahedrally coordinated Fe sites (on which Fe may be partially replaced by minor Al), two unique tetrahedrally coordinated T (As or P) sites, eight O, three O h , three O w and nine H sites. The topology features zig-zag chains along $$\left[\overline{1}10\right]$$ of dimers built of two edge-sharing FeO 6 octahedra corner-linked by a third FeO 6 octahedron. The chains are corner-linked by the T O 4 tetrahedra thus establishing a mixed octahedral-tetrahedral framework with a T :Fe ratio of 0.67, a pronounced layered arrangement parallel to (001) and narrow channels along [010]. Medium-strong to weak hydrogen-bonds provide additional strengthening of the structure. The topology is closely related to that of the recently described, triclinic aluminium phosphate afmite.

Description: Écrinsite, ideally AgTl 3 Pb 4 As 11 Sb 9 S 36 , is a new thallium sulphosalt species found in the Jas Roux As–Sb–Pb–Tl–Hg–Ag deposit, Parc national des Écrins, Département des Hautes-Alpes, France. Associated minerals in four different samples are jasrouxite, stibnite, smithite, guettardite, chabournéite, pierrotite and As-bearing zink enite. Écrinsite is opaque with metallic lustre. It is brittle without any discernible cleavage and with conchoidal fracture. In reflected light écrinsite is white, pleochroism is not discernible. Internal reflections are absent. In crossed polarisers, anisotropism is distinct, with rotation tints in shades of grey. The reflectance data (%, air) are: 37.3, 38.6 at 470 nm, 35.2, 36.7 at 546 nm, 34.0, 35.5 at 589 nm and 32.0, 33.3 at 650 nm. Mohs hardness is 3–31/2, microhardness VHN 25 is in the range 175–201, with a mean value of 189 kg mm –2 . Average results of 20 electron-microprobe analyses for the structurally investigated grain are (in wt%): Ag 2.03(10), Cu 0.02(1), Tl 14.57(20), Pb 16.23(32), Sb 23.97(25), As 17.87(17), S 25.20(15), total 99.88 (15), corresponding to Ag 0.87 Cu 0.02 Tl 3.28 Pb 3.61 Sb 9.06 As 10.98 S 36.19 (on the basis of 28 Me + 36S = 64 apfu ). The simplified formula, AgTl 3 Pb 4 Sb 9 As 11 S 36 , is in accordance with the results of the crystal-structure analysis and may be derived from the ideal baumhauerite formula, Pb 12 As 16 S 36 , by substitution of Sb for As and [(Tl,Ag) + + (As,Sb) 3+ ] 2Pb 2+ . The density, 4.96 g cm –3 , was calculated using the ideal formula. Écrinsite has a triclinic cell, space group P 1, with a = 8.080(2), b = 8.533(2), c = 22.613(4) Å, α = 90.23(3) ° , β = 97.17(3) ° , = 90.83(3) ° , V = 1546.7(6) Å 3 , and Z = 1. The strongest five lines in the (calculated) powder-diffraction pattern are [ d in Å ( I )( h k l )]: 4:14(68)(1 0 5), 3.72(92)(1 0 5), 3:56 N (100)(1 0 6); 3:53(80) (1 2 2) and 3.48(72)(1 2 2). Écrinsite is a new member of the sartorite homologous series with 1,2 = 3, 4, i.e ., N = 3.5. Four other members share the same N value as écrinsite: baumhauerite, argentobaumhauerite, boscardinite and bernarlottiite. By comparison to the closely related boscardinite (ideally Tl 2 Pb 8 Sb 14 As 4 S 36 ), écrinsite is characterised by both an excess of As over Sb and a distinctly higher substitution of [(Tl,Ag) + (As,Sb) 3+ ] 2Pb 2+ . Baumhauerite and bernarlottiite are basically unsubstituted members, whereas argentobaumhauerite has a Ag substitution, without Tl.

Description: 〈span〉Argentoliveingite, ideally Ag〈sub〉3+〈span〉x〈/span〉〈/sub〉Pb〈sub〉36−2〈span〉x〈/span〉〈/sub〉As〈sub〉51+〈span〉x〈/span〉〈/sub〉S〈sub〉112〈/sub〉 (0 ≤ 〈span〉x〈/span〉 〈 0.5), is a new silver-bearing sulphosalt species found in the Lengenbach deposit, Binntal, Canton Wallis, Switzerland. Associated minerals in the holotype, an old museum specimen, are baumhauerite and argentobaumhauerite. In other samples, hendekasartorite, liveingite, rathite and dufrénoysite are present. Argentoliveingite is dark grey and opaque with metallic lustre and a black streak. It is brittle without any discernible cleavage and with conchoidal fracture. In reflected light argentoliveingite is white, pleochroism is not discernible. Red internal reflections are seen on thin edges or at grain boundaries. In crossed polarisers, anisotropism is moderate in dark grey – neutral rotation tints. The reflectance data [〈span〉R〈/span〉〈sub〉min〈/sub〉, 〈span〉R〈/span〉〈sub〉max〈/sub〉 (%), in air] are: 36.6, 41.5 at 470 nm, 34.4, 39.4 at 546 nm, 32.9, 37.8 at 589 nm and 30.7, 35.2 at 650 nm. Mohs hardness is four, microhardness VHN〈sub〉25〈/sub〉 exhibits a range 208–225 kg mm〈sup〉−2〈/sup〉, with a mean value of 217 kg mm〈sup〉−2〈/sup〉. The average result of 22 electron-microprobe spot analyses for the structurally investigated grain is (in wt%): Ag 2.31(4), Tl 0.35(12), Pb 46.65(26), Sb 0.83(10), As 25.36(14), S 24.27(17), total 99.97(20), corresponding to Ag〈sub〉3.17〈/sub〉Tl〈sub〉0.40〈/sub〉Pb〈sub〉33.31〈/sub〉Sb〈sub〉1.01〈/sub〉As〈sub〉50.08〈/sub〉S〈sub〉112.02〈/sub〉 (on the basis of 88Me + 112S = 200 atoms per formula unit, 〈span〉apfu〈/span〉). The ideal formula is in accordance with the results of the crystal-structure analysis and may be derived from the double ideal liveingite formula, Pb〈sub〉40〈/sub〉As〈sub〉48〈/sub〉S〈sub〉112〈/sub〉, by minor substitution of Sb for As, and the independent, heterovalent [(Ag,Tl)〈sup〉+〈/sup〉 + (As,Sb)〈sup〉3+〈/sup〉] ↔ 2Pb〈sup〉2+〈/sup〉 substitution. The density, 5.23 g cm〈sup〉−3〈/sup〉, was calculated using the empirical formula. Argentoliveingite is triclinic, space group 〈span〉P〈/span〉1¯ (no. 2), with 〈span〉a〈/span〉 = 7.905(2), 〈span〉b〈/span〉 = 8.469(2), 〈span〉c〈/span〉 = 137.96(4) Å, α = 89.592(2), β = 88.969(2), γ = 89.893(2)°, 〈span〉V〈/span〉 = 9235(5) Å〈sup〉3〈/sup〉 and 〈span〉Z〈/span〉 = 2. The 〈span〉c〈/span〉 axis is double the 〈span〉b〈/span〉 axis of liveingite and represents the longest unit-cell parameter for a known natural sulphosalt. The strongest five lines in the (calculated) powder-diffraction pattern are [〈span〉d〈/span〉 in Å(I)(〈span〉h〈/span〉,〈span〉k〈/span〉,〈span〉l〈/span〉)]: 3.781(85)(2¯,0,10), 3.668(100)(1¯,0,33), 3.553(83)(1,0,35), 3.009(91)(1¯,2,27) and 2.938(94)(1,2¯,29). Argentoliveingite is a homeotype of liveingite and a new member of the sartorite homologous series with 〈span〉N〈/span〉 = 3.67, and with a limited extent of the uncoupled substitutions of [Ag〈sup〉+〈/sup〉 + As〈sup〉3+〈/sup〉] for 2Pb〈sup〉2+〈/sup〉 and [Tl〈sup〉+〈/sup〉 + As〈sup〉3+〈/sup〉] for 2Pb〈sup〉2+〈/sup〉. In argentoliveingite the sequence of alternating 〈span〉N〈/span〉 = 3 and 〈span〉N〈/span〉 = 4 slabs is different from that in liveingite and is further modified by alternation of three, chemically distinct, types of 〈span〉N〈/span〉 = 4 slabs. The length and arrangement of crankshaft chains of short As–S bonds differ between different slabs, and especially between the 〈span〉N〈/span〉 = 4 slabs of liveingite and argentoliveingite. The crystal structures of liveingite and Ag-bearing liveingite (both quantitatively analysed) have been refined for comparison purposes. The uncertain relationship with the phase “rathite-IV” is discussed.〈/span〉

Description: 〈span〉Argentoliveingite, ideally Ag〈sub〉3+〈span〉x〈/span〉〈/sub〉Pb〈sub〉36−2〈span〉x〈/span〉〈/sub〉As〈sub〉51+〈span〉x〈/span〉〈/sub〉S〈sub〉112〈/sub〉 (0 ≤ 〈span〉x〈/span〉 〈 0.5), is a new silver-bearing sulphosalt species found in the Lengenbach deposit, Binntal, Canton Wallis, Switzerland. Associated minerals in the holotype, an old museum specimen, are baumhauerite and argentobaumhauerite. In other samples, hendekasartorite, liveingite, rathite and dufrénoysite are present. Argentoliveingite is dark grey and opaque with metallic lustre and a black streak. It is brittle without any discernible cleavage and with conchoidal fracture. In reflected light argentoliveingite is white, pleochroism is not discernible. Red internal reflections are seen on thin edges or at grain boundaries. In crossed polarisers, anisotropism is moderate in dark grey – neutral rotation tints. The reflectance data [〈span〉R〈/span〉〈sub〉min〈/sub〉, 〈span〉R〈/span〉〈sub〉max〈/sub〉 (%), in air] are: 36.6, 41.5 at 470 nm, 34.4, 39.4 at 546 nm, 32.9, 37.8 at 589 nm and 30.7, 35.2 at 650 nm. Mohs hardness is four, microhardness VHN〈sub〉25〈/sub〉 exhibits a range 208–225 kg mm〈sup〉−2〈/sup〉, with a mean value of 217 kg mm〈sup〉−2〈/sup〉. The average result of 22 electron-microprobe spot analyses for the structurally investigated grain is (in wt%): Ag 2.31(4), Tl 0.35(12), Pb 46.65(26), Sb 0.83(10), As 25.36(14), S 24.27(17), total 99.97(20), corresponding to Ag〈sub〉3.17〈/sub〉Tl〈sub〉0.40〈/sub〉Pb〈sub〉33.31〈/sub〉Sb〈sub〉1.01〈/sub〉As〈sub〉50.08〈/sub〉S〈sub〉112.02〈/sub〉 (on the basis of 88Me + 112S = 200 atoms per formula unit, 〈span〉apfu〈/span〉). The ideal formula is in accordance with the results of the crystal-structure analysis and may be derived from the double ideal liveingite formula, Pb〈sub〉40〈/sub〉As〈sub〉48〈/sub〉S〈sub〉112〈/sub〉, by minor substitution of Sb for As, and the independent, heterovalent [(Ag,Tl)〈sup〉+〈/sup〉 + (As,Sb)〈sup〉3+〈/sup〉] ↔ 2Pb〈sup〉2+〈/sup〉 substitution. The density, 5.23 g cm〈sup〉−3〈/sup〉, was calculated using the empirical formula. Argentoliveingite is triclinic, space group 〈span〉P〈/span〉1¯ (no. 2), with 〈span〉a〈/span〉 = 7.905(2), 〈span〉b〈/span〉 = 8.469(2), 〈span〉c〈/span〉 = 137.96(4) Å, α = 89.592(2), β = 88.969(2), γ = 89.893(2)°, 〈span〉V〈/span〉 = 9235(5) Å〈sup〉3〈/sup〉 and 〈span〉Z〈/span〉 = 2. The 〈span〉c〈/span〉 axis is double the 〈span〉b〈/span〉 axis of liveingite and represents the longest unit-cell parameter for a known natural sulphosalt. The strongest five lines in the (calculated) powder-diffraction pattern are [〈span〉d〈/span〉 in Å(I)(〈span〉h〈/span〉,〈span〉k〈/span〉,〈span〉l〈/span〉)]: 3.781(85)(2¯,0,10), 3.668(100)(1¯,0,33), 3.553(83)(1,0,35), 3.009(91)(1¯,2,27) and 2.938(94)(1,2¯,29). Argentoliveingite is a homeotype of liveingite and a new member of the sartorite homologous series with 〈span〉N〈/span〉 = 3.67, and with a limited extent of the uncoupled substitutions of [Ag〈sup〉+〈/sup〉 + As〈sup〉3+〈/sup〉] for 2Pb〈sup〉2+〈/sup〉 and [Tl〈sup〉+〈/sup〉 + As〈sup〉3+〈/sup〉] for 2Pb〈sup〉2+〈/sup〉. In argentoliveingite the sequence of alternating 〈span〉N〈/span〉 = 3 and 〈span〉N〈/span〉 = 4 slabs is different from that in liveingite and is further modified by alternation of three, chemically distinct, types of 〈span〉N〈/span〉 = 4 slabs. The length and arrangement of crankshaft chains of short As–S bonds differ between different slabs, and especially between the 〈span〉N〈/span〉 = 4 slabs of liveingite and argentoliveingite. The crystal structures of liveingite and Ag-bearing liveingite (both quantitatively analysed) have been refined for comparison purposes. The uncertain relationship with the phase “rathite-IV” is discussed.〈/span〉