Lopatkaite, ideally Pb10As2Sb6S22 (Z=4), is a new arsenic-bearing sulfosalt found in the Madoc deposit, Taylor Pit, Ontario, Canada. Associated minerals in the holotype specimen are boulangerite, veenite, and sterryite, all embedded in a calcite matrix. Lopatkaite is greyish black and opaque, with metallic lustre and dark-grey streak. It is brittle without any discernible cleavage and parting and has a Mohs hardness of 3-3.5. In reflected light lopatkaite is greyish white, with distinct bireflectance and pleochroism from white to grey, especially in oil. Under crossed polarisers, anisotropism is distinct, with rotation tints in shades of grey. Reflectance measurements in air yield the following Rmin/Rmax values based on the standard wavelengths (Commission on Ore Mineralogy, COM): 37.0 % / 39.3 % (470 nm), 34.1 % / 36.9 % (546 nm), 33.1 % / 36.2 % (589 nm), and 31.3 % / 34.1 % at (650 nm). The average result of four electron probe microanalyses for the structurally investigated grain is as follows (in wt %): Pb 57.81(4), As 3.53(8), Sb 20.03(6), S 19.08(6), and total 100.46(22), corresponding to Pb10.28(3)As1.74(4)Sb6.06(3)S21.92(3) (based on 18Me + 22S = 40 atoms per asymmetric unit). The density calculated using the empirical formula is 6.168 Mg m-3. Single-crystal X-ray diffraction data show lopatkaite to be monoclinic, space group P21/c (no. 14), with a=8.0806(6), b=23.3597(18), c=21.4880(16) & Aring;, beta=100.7090(10)degrees, V=3985.4(5) & Aring;3, and Z=4. The seven strongest lines in the (calculated) powder diffraction pattern are as follows (d in & Aring; (intensity) (hkl)): 3.728(39) 211, 3.712(100) 035, 3.653(35) 062, 2.804(41) -261, 2.780(43) 260, 2.779(38) -262, and 2.020(47) -402. The ideal formula is in accordance with the results of the crystal structure analysis, Pb10.336As1.567Sb6.088S22 , and may be derived from the ideal boulangerite formula, Pb10Sb8S22 (Z=4), by means of substitution of two Sb atoms with two As atoms. Lopatkaite is an isotype of boulangerite, differing by dominant As occupancy at two crystallographically independent mixed (Sb, As) sites. This dominant-site substitution defines lopatkaite as the arsenic-dominant isotype of boulangerite and justifies its recognition as a distinct mineral species. Lopatkaite is also a new member of the rod-based family of sulfosalts.

Abstract. Keutschite, Cu2AgAsS4, is a new mineral from the Ag–Pb–Zn deposit at Uchucchacua, Oyon District, Catajambo, Lima Department, Peru. The mineral occurs as metallic, highly lustrous, blocky, free-standing crystals measuring up to 3 mm. These crystals exhibit a grey colour with a slight green-brassy tint and a grey-black streak, and they are present on both manganoquadratite and proustite. It was observed that keutschite was brittle, and no fractures or cleavages were identified. In plane-polarised light, keutschite exhibits a grey hue devoid of any discernible internal reflections. It demonstrates a minimal manifestation of pleochroism and exhibits a negligible degree of bireflectance. Between crossed polars, the mineral is weakly anisotropic with rotation tints in shades of greenish grey to grey. Reflectance measurements in air yield the following Rmin/Rmax values for wavelengths recommended by the Commission on Ore Mineralogy of the International Mineralogical Association: 25.2/26.1 (470 nm), 29.6/29.4 (546 nm), 29.4/29.2 (589 nm), and 28.5/28.6 (650 nm). Keutschite crystallises in a tetragonal geometry and is classified as space group I4‾2m. The unit cell parameters are as follows: a=5.5834(15), c=10.021(3) Å, V=312.40(14) Å3, a:b:c=1:1:0.897, and Z=2. The crystal structure was refined to R1=0.0199 for 286 reflections with I>3σ(I). The structure of keutschite is derived from that of sphalerite by ordered substitution of Zn atoms, analogous to the substitution pattern for deriving stannite from sphalerite. The crystal structure of the mineral can be derived from that of luzonite through the complete substitution of one of the two copper sites with silver. The five strongest intensities in the X-ray powder diagram are [d in Å (intensity) hkl]: 3.101 (100) 110; 2.792 (11) 200; 1.974 (20) 220; 1.665 (34) 204; and 2.846 (27) 312. The chemical formula, as determined by electron microprobe analysis, is Cu2.05Ag0.96(As0.95Sb0.04)Σ0.99S4.00 (based on eight atoms). The ideal formula, derived from the crystal structure, is Cu2AgAsS4. The name honours Frank Keutsch (born 1971) for his contribution to the mineralogy of the Uchucchacua deposit.

Abstract. Spaltiite is a new thallium sulfosalt with the ideal formula of Tl2Cu2As2S5. It was found on a dump of the famous mineral locality Lengenbach (Binntal, Canton Valais, Switzerland). A small piece of pure white Triassic dolomite belonging to the Penninic Monte Leone Nappe hosts three euhedral long prismatic to lath-like spaltiite crystals, each approximately 2 mm in length but only ∼0.2 mm thin. The hand specimen contains small quantities of pyrite, drechslerite and hatchite. The spaltiite crystals are greyish to black in colour and extremely soft. The Mohs' hardness is 1.5–2 (VHN15 ranges from 30 to 65, mean 47 kg mm−2). The mono-clinic crystals have a perfect cleavage parallel to {100}, which produces minute and plastic slabs. Reflectance measurements in air yield the following Rmin/Rmax values based on the standard wavelengths (Commission on Ore Mineralogy, COM): 27.0 % / 32.6 % (470 nm); 26.8 % / 32.1 % (546 nm); 26.0 % / 31.1 % (589 nm); and 24.8 % / 29.3 % (650 nm). Averaged electron-microprobe analyses (n=10) gave (in wt %) Tl 47.41(19), Cu 15.46(12), Ag 0.15(6), As 17.36(14), Sb 0.41(5) and S 19.20(8), total 99.99(32). The empirical formula is Tl1.94Cu2.04Ag0.01As1.95Sb0.03S5.03, calculated based on 11 apfu. The large crystals exhibit a remarkably homogeneous composition. Spaltiite crystallises in space group P21/c (a=15.791(8), b=10.000(5), c=6.323(3) Å, β=99.25(8)°, V=985.5(8) Å3). The crystal structure was determined from single-crystal X-ray diffraction data (R1=12.18 % for 4753 data, with Fo>4σ (Fo) and 101 variable parameters). Spaltiite exhibits a pronounced layered atomic arrangement: two polar Cu–As layers in (1/4 y z) and (3/4 y z), respectively, are related by inversion symmetry. Sandwiched between them are the Tl atoms. These two layers are centred in (0 y z) and (1/2 y z), centrosymmetric but topologically and crystallographically distinct. The eight strongest intensities in the X-ray powder diagram are [d in Å (intensity) hkl]: 3.914 (40) 021; 2.988 (63) 510; 3.496 (45) 311; 2.869 (45) 5‾11; 2.652 (36) 3‾31; 3.646 (34) 2‾21; 2.506 (29) 040; 2.762 (26) 202. The name of the new mineral originates from the nickname “spalti”, which was used during laboratory studies, illustrating the extremely pronounced cleavage (in German, “spalten” means cleave).

Keutschite, Cu2AgAsS4, is a new mineral from the Ag-Pb-Zn deposit at Uchucchacua, Oyon District, Catajambo, Lima Department, Peru. The mineral occurs as metallic, highly lustrous, blocky, free-standing crystals measuring up to 3 mm. These crystals exhibit a grey colour with a slight green-brassy tint and a grey-black streak, and they are present on both manganoquadratite and proustite. It was observed that keutschite was brittle, and no fractures or cleavages were identified. In plane-polarised light, keutschite exhibits a grey hue devoid of any discernible internal reflections. It demonstrates a minimal manifestation of pleochroism and exhibits a negligible degree of bireflectance. Between crossed polars, the mineral is weakly anisotropic with rotation tints in shades of greenish grey to grey. Reflectance measurements in air yield the following R-min/R(max )values for wavelengths recommended by the Commission on Ore Mineralogy of the International Mineralogical Association: 25.2/26.1 (470 nm), 29.6/29.4 (546 nm), 29.4/29.2 (589 nm), and 28.5/28.6 (650 nm). Keutschite crystallises in a tetragonal geometry and is classified as space group I4 & oline;2m. The unit cell parameters are as follows: a=5.5834(15), c=10.021(3) & Aring;, V=312.40(14) & Aring;(3), a:b:c=1:1:0.897, and Z=2. The crystal structure was refined to R1=0.0199 for 286 reflections with I>3 sigma(I). The structure of keutschite is derived from that of sphalerite by ordered substitution of Zn atoms, analogous to the substitution pattern for deriving stannite from sphalerite. The crystal structure of the mineral can be derived from that of luzonite through the complete substitution of one of the two copper sites with silver. The five strongest intensities in the X-ray powder diagram are [d in & Aring; (intensity) hkl]: 3.101 (100) 110; 2.792 (11) 200; 1.974 (20) 220; 1.665 (34) 204; and 2.846 (27) 312. The chemical formula, as determined by electron microprobe analysis, is Cu2.05Ag0.96(As0.95Sb0.04)(Sigma 0.99)S-4.00 (based on eight atoms). The ideal formula, derived from the crystal structure, is Cu2AgAsS4. The name honours Frank Keutsch (born 1971) for his contribution to the mineralogy of the Uchucchacua deposit.

Erzwiesite, ideally Ag8Pb12Bi16S40, Z= 1, is a new sulfosalt mineral discovered in the Erzwies mining area, Gastein Valley, Salzburg Province, Austria. The mineral occurs as small black, irregular needle-like crystals mixed with galena and heyrovsk & yacute;ite in a quartz matrix. In reflected light, erzwiesite is greyish white. Under crossed polars it is distinctly anisotropic, and the rotation tints change from pale brown to pale bluish grey to dark brown. Reflectance measurements in air yield the following R-min/R-max values based on the standard wavelengths (Commission on Ore Mineralogy, COM): 44.5/47.6 (470 nm), 41.9/45.0 (546 nm), 41.5/44.5 (589 nm), and 40.4/43.6 (650 nm). The Mohs' hardness is 3-3.5 (VHN50 ranges from 195 to 224, mean 210 kg mm(-2)). Averaged electron-microprobe analyses (n= 6) gave (in wt %) Ag 11.10(27), Cu 0.04(3), Pb 29.50(77), Cd 0.17(1), Bi 42.90(63), Te 0.21(14), Se 0.08(5), and S 16.08(11), with a total of 100.10(63). The empirical formula is Ag8.18Cu0.05Pb11.31Cd0.12Bi16.30Sb0.01S39.81Te0.13Se0.06 (based on 76 apfu). The calculated density is 7.075 g cm(-3) using the empirical formula. Erzwiesite crystallises in space group Cmcm (a= 4.085(5), b= 13.462(15), c= 33.92(4) & Aring;, and V= 1866(4) & Aring;3). The crystal structure was determined from single-crystal X-ray diffraction data (R-1= 5.24 % for 308 data with F-o > 4 sigma(F-o) and 51 variable parameters). The structural formula is Ag8.64Pb11.04Bi16.32S40. The seven strongest lines in the X-ray powder diagram are [d in & Aring; (intensity) hkl] 3.588 (64) 028, 3.387 (98) 115, 3.349 (37) 041, 3.288 (85) 029, 2.919 (100)133, 2.846 (99)134, and 2.039(43) 157. Erzwiesite is the first natural (8 : 8) homologue of the lillianite homologous series and is named after its type locality.

Abstract The As-containing proto-owyheeite [Ag 2.26(07) Cu 0.14(01) Tl 0.13(03) Pb 9.40(06) Sb 10.96(07) As 0.38(02) S 28 , P 2 1 / n , a = 8.1696 (2) Å, b = 27.3377 (4) Å, c = 22.8584 (4) Å, β = 90.078 (2)°, V = 5105.15 (17) Å 3 ] and sardashtite [Ag 2.23(06) Cu 0.65(02) Pb 10.34(07) Sb 8.96(13) As 1.83(02) S 28 , P 2 1 / n , a = 8.2038 (3) Å, b = 27.1002 (10) Å, c = 22.7885 (9) Å, β = 90.1850 (10)°, V = 5066.4 (3) Å 3 ] crystallize as twofold superstructures (doubling of the a -axis with respect to a hypothetical basic structure), which are closely related to the structure of owyheeite. In contrast to owyheeite, which features systematic (approximate) cyclic twinning by 120° rotation about [100], proto-owyheite and sardashtite are twinned by pseudo-merohedry (reflection at [100] or equivalently [001]), which made structural elucidation significantly less troublesome.

Spaltiite is a new thallium sulfosalt with the ideal formula of Tl2Cu2As2S5. It was found on a dump of the famous mineral locality Lengenbach (Binntal, Canton Valais, Switzerland). A small piece of pure white Triassic dolomite belonging to the Penninic Monte Leone Nappe hosts three euhedral long prismatic to lath-like spaltiite crystals, each approximately 2 mm in length but only similar to 0.2 mm thin. The hand specimen contains small quantities of pyrite, drechslerite and hatchite. The spaltiite crystals are greyish to black in colour and extremely soft. The Mohs' hardness is 1.5-2 (VHN15 ranges from 30 to 65, mean 47 kg mm(-2)). The mono-clinic crystals have a perfect cleavage parallel to {100}, which produces minute and plastic slabs. Reflectance measurements in air yield the following R-min/R-max values based on the standard wavelengths (Commission on Ore Mineralogy, COM): 27.0 % / 32.6 % (470 nm); 26.8 % / 32.1 % (546 nm); 26.0 % / 31.1 % (589 nm); and 24.8 % / 29.3 % (650 nm). Averaged electron-microprobe analyses (n=10) gave (in wt %) Tl 47.41(19), Cu 15.46(12), Ag 0.15(6), As 17.36(14), Sb 0.41(5) and S 19.20(8), total 99.99(32). The empirical formula is Tl1.94Cu2.04Ag0.01As1.95Sb0.03S5.03, calculated based on 11 apfu. The large crystals exhibit a remarkably homogeneous composition. Spaltiite crystallises in space group P2(1/c) (a=15.791(8), b=10.000(5), c=6.323(3) & Aring;, beta=99.25(8)degrees, V=985.5(8) & Aring;(3)). The crystal structure was determined from single-crystal X-ray diffraction data (R-1=12.18 % for 4753 data, with F-o>4 sigma (F-o) and 101 variable parameters). Spaltiite exhibits a pronounced layered atomic arrangement: two polar Cu-As layers in (1/4 yz) and (3/4 yz), respectively, are related by inversion symmetry. Sandwiched between them are the Tl atoms. These two layers are centred in (0 yz) and (1/2 yz), centrosymmetric but topologically and crystallographically distinct. The eight strongest intensities in the X-ray powder diagram are [d in & Aring; (intensity) hkl]: 3.914 (40) 021; 2.988 (63) 510; 3.496 (45) 311; 2.869 (45) 5 & oline;11; 2.652 (36) 3 & oline;31; 3.646 (34) 2 & oline;21; 2.506 (29) 040; 2.762 (26) 202. The name of the new mineral originates from the nickname "spalti", which was used during laboratory studies, illustrating the extremely pronounced cleavage (in German, "spalten" means cleave).

Abstract. Erzwiesite, ideally Ag8Pb12Bi16S40, Z= 1, is a new sulfosalt mineral discovered in the Erzwies mining area, Gastein Valley, Salzburg Province, Austria. The mineral occurs as small black, irregular needle-like crystals mixed with galena and heyrovskýite in a quartz matrix. In reflected light, erzwiesite is greyish white. Under crossed polars it is distinctly anisotropic, and the rotation tints change from pale brown to pale bluish grey to dark brown. Reflectance measurements in air yield the following Rmin/Rmax values based on the standard wavelengths (Commission on Ore Mineralogy, COM): 44.5/47.6 (470 nm), 41.9/45.0 (546 nm), 41.5/44.5 (589 nm), and 40.4/43.6 (650 nm). The Mohs' hardness is 3–3.5 (VHN50 ranges from 195 to 224, mean 210 kg mm−2). Averaged electron-microprobe analyses (n= 6) gave (in wt %) Ag 11.10(27), Cu 0.04(3), Pb 29.50(77), Cd 0.17(1), Bi 42.90(63), Te 0.21(14), Se 0.08(5), and S 16.08(11), with a total of 100.10(63). The empirical formula is Ag8.18Cu0.05Pb11.31Cd0.12Bi16.30Sb0.01S39.81Te0.13Se0.06 (based on 76 apfu). The calculated density is 7.075 g cm−3 using the empirical formula. Erzwiesite crystallises in space group Cmcm (a= 4.085(5), b= 13.462(15), c= 33.92(4) Å, and V= 1866(4) Å3). The crystal structure was determined from single-crystal X-ray diffraction data (R1= 5.24 % for 308 data with Fo > 4σ(Fo) and 51 variable parameters). The structural formula is Ag8.64Pb11.04Bi16.32S40. The seven strongest lines in the X-ray powder diagram are [d in Å (intensity) hkl] 3.588 (64) 028, 3.387 (98) 115, 3.349 (37) 041, 3.288 (85) 029, 2.919 (100)133, 2.846 (99)134, and 2.039(43) 157. Erzwiesite is the first natural (8 : 8) homologue of the lillianite homologous series and is named after its type locality.

Sulfosalts are known to be commonly found in the majority of hydrothermal Au-Ag deposits, giving important information about the evolution of the mineralization and the physicochemical properties of the hydrothermal fluid. The Sacaramb epithermal Au-Ag-Te ore deposit located in the South Apuseni Mountains, Romania, is one of the most known telluride deposits in Europe and the World. It consists of four major vein groups (Nepomuc, Magdalena-Carolina, Longhin-Antelonghin and Erzbau) developed in the central structure of the Sacaramb stratovolcano. The ore mineralogy and crystal chemistry of more than 30 sulfosalts are presented in this paper, mostly being new occurrences. Significant thallium enrichment has been discovered in relationship to the youngest mineralization. This is the first known presence of Tl-sulfosalts in an Au-Ag telluride ore deposit. Oscillatory zoning present in the tetrahedrite group and bournonite-seligmanite series indicate a strong variation of As and Sb in the ore fluid, especially in the later stages. The presence of greigite and sulfosalts indicates temperatures below 200 degrees C in later stages of the mineralization. New data on fahlores from Sacaramb reveal complex physicochemical conditions and the presence of Mn-dominant members. A new model of the mineralization evolution of the Sacaramb ore deposit was elaborated based on microscopic observations and chemical analyses of the new sulfosalt-telluride-sulfide assemblages.

The “Weltmuseum Wien” owns a large collection of kris daggers from Indonesia. These objects are famous for their metal blades consisting of numerous layers made by a complicated forging process involving repeated folding and welding of the individual layers. There is a widespread belief that some krises were manufactured by adding meteoritic nickel–iron from the Prambanan meteorite that fell in Central Java and is known since the late 18th century. In our study, we investigated a selection of five Ni‐rich krises from this collection with the aim to identify in their blades nickel–iron from Prambanan or another iron meteorite source. To obtain a better insight into the forging process, we investigated analog objects that were produced by a forging procedure similar to the one applied in the production of original krises and by using iron meteorite material from the meteorites Campo del Cielo and Gibeon as admixture. These investigations were performed by nondestructive analytical techniques, including handheld X‐ray fluorescence (HH‐XRF) analysis, scanning electron microscopy (SEM), and electron microprobe (EMP) analysis. The original daggers were investigated by HH‐XRF and micro‐X‐ray fluorescence (μ‐XRF) analysis, as well as by portable laser ablation (pLA) subsampling followed by trace element analysis using inductively coupled plasma mass spectrometry (ICP‐MS). By comparing the data obtained for both materials, we demonstrate that the main difficulties in identifying the presence of a meteoritic component in the kris daggers are due to the exclusive use of (quasi‐)nondestructive methods in combination with locally varying surface heterogeneities, resulting from contamination, corrosion, and etching features. We also show that the presence of significant amounts of Ni and Co (in the wt% range) in a premodern kris dagger does not imply that it was manufactured with an admixture of meteoritic metal. We found that among the five krises investigated, only a single dagger (no. 900382) was manufactured with the possible admixture of nickel–iron from the Prambanan iron meteorite, as it contains high concentrations of siderophile elements and has a Ni/Co ratio comparable to that of the meteorite.

The crystal structure of rouxelite from the Monte Arsiccio mine, Italy, has been investigated using single-crystal X-ray diffraction (SCXRD) to clarify its crystallography and crystal chemistry. The structure is described in space group C-1, with lattice parameters a= 43.1883(12), b= 8.1037(2), c= 38.1470(10) & Aring;, alpha= 96.001(2), beta= 116.615(2), gamma= 95.372(2)degrees, and V = 11721.7(6) & Aring;3. The structure can be considered as being a twofold superstructure (doubled b cell parameter) of the C2/m rouxelite structure previously reported from Buca della Vena mine. The asymmetric unit in the structure of rouxelite contains 53 cation sites and 66 anion sites. The metal sites are composed of 22 Pb positions, 28 Sb positions, one Hg position, and two Cu positions. Among the Pb sites, four are mixed with Tl, Sb, Ag, and As and two are split. Among the Sb sites, three Sb sites are mixed with Pb and As and three are split. The Hg position includes Ag, and two sulfur sites (S65 and S66) are partially occupied. Final refinement, performed as a twin with volume ratios of 0.5489 : 0.4510(14), resulted in an R1 value of 0.0855 for 55765 unique reflections. The crystal under investigation was an intergrowth with a second domain whose cell parameters correspond to those of launayite. The resulting structural formulae obtained from the SCXRD study for the unit cell is either Cu8Ag2.08Hg3.068Tl2Pb83.568As1.448Sb111.836S261.52 (for Z = 1, ch = 2.16) or Cu8Ag2.09Hg3.064Tl2Pb83.556As1.452Sb111.84S261.32O1.52 (for Z = 1, ch = -0.47) (O content could not be reliably determined), making the definition of an ideal formula difficult. Additionally, a substantial volume of new chemical data for rouxelite has been included, covering both the Monte Arsiccio mine and the neighbouring Buca della Vena occurrences, thereby enhancing the previously published data. The crystal chemistry, substitution mechanisms, and modular description of rouxelite as well as the modular relationship to other minerals are also addressed.

The crystal structure of launayite, ideally Cu2Pb20(Sb,As)26S60 (Z=4) from Taylor Pit, Madoc, Ontario, Canada, has been solved for the first time using the single-crystal X-ray diffraction (SCXRD) method. The mineral is composed of distinct superstructures that can be derived from the same parent structure. The structure of the main component is monoclinic and has been solved in the space group P2/a, with cell parameters a=42.6466(14), b=8.0381(2), c=34.3957(10) Å, β=64.684(2) °, and V=10 658.4(6) Å3 from an untwined crystal. The asymmetric unit of launayite contains 48 cation sites and 60 sulfur sites. Final refinement resulted in an R1 value of 0.0955 for 11 741 unique reflections. The structural formula obtained from SCXRD study is Cu2Pb20.330Sb23.024As2.689S60, Z=4, in agreement with the formula Cu2.078Ag0.059Tl0.057Pb20.404Sb22.830As2.772S59.80 from microprobe analysis. The structure of launayite can be viewed both as a boxwork structure and as a rod-based structure. The modular description of the launayite structure reveals a very close relationship with the structure of rouxelite: the parent structures of both can be regarded as merotypes. A full comparison of the crystal chemistry and modular description of both structures is presented.

Prachařite, ideally CaSb 5+ 2 (As 3+ 2 O 5 ) 2 O 2 ·10H 2 O, is a new mineral found in underground workings of the Plaka Mine No. 80, Plaka, Lavrion Mining District, Attica, Greece. It occurs as colourless to white, thin tabular hexagonal, in general sharp crystals up to 2.5 mm in diameter, and is associated with pharmacolite, sulphur and very rare smamite Ca 2 Sb(OH) 4 [H(AsO 4 ) 2 ]·6H 2 O on a matrix composed of sphalerite, galena and carbonate gangue. Prachařite is translucent to transparent, with a glassy lustre, white streak, a good cleavage parallel to 0001 and a distinct cleavage parallel to 10 1 0. It is non-luminescent, brittle, and has an uneven fracture, a Mohs hardness of 2–2.5 and X-ray density D x = 2.848 g/cm 3 , D calc. = 2.836–2.853 g/cm 3 (for two measured compositions). Optically, it is uniaxial negative, with ω = 1.619(1) and ε = 1.553(1). Prachařite is trigonal, space group P 3 c 1 (no. 165), with a = 13.951(2), c = 19.899(2) Å, V = 3354.1(10) Å 3 and Z = 6. Strongest lines in the X-ray powder diffraction pattern are [ d in Å ( I ) hkl ]: 9.894 (100) 002; 6.045 (8) 200; 5.156 (10) 202; 4.946 (11) 004; 3.297 (19) 311, 006, 222; 2.988 (22) 400, 313, 116. Two sets of independent electron probe micro-analyses yielded (wt

AbstractThe chemistry and the crystal structure of the recently described mineral argentopolybasite are critically discussed based on the study of two new occurrences of the mineral: Gowganda, Timiskaming District, Ontario, Canada and IXL Mine, Silver Mountain mining district, Alpine County, California.The crystal structure of argentopolybasite can be described as the sequence, along the c axis, of two alternating layers: a [Ag6Sb2S7]2–A layer and a [Ag10S4]2+B layer. In the B layer there are linearly-coordinated metal positions (B sites), which are usually occupied by copper in all members of the pearceite–polybasite group, resulting in a B-layer composition [Ag9CuS4]2+. In argentopolybasite, however, Ag fills all the metal sites in both A and B layers. By means of a multi-regression analysis on 67 samples of the pearceite–polybasite group, which were studied by electron microprobe and single-crystal X-ray diffraction, the effect of Ag, Sb and Se on the B sites of the B layer was modelled. Although the nomenclature rules for these minerals are based on chemical data only, we think this approach is useful to evaluate the goodness of the refinement of the structure (Ag/Cu disorder) and thus fundamental to discriminate different members of the pearceite–polybasite group.

Owyheeite [Cu0.09 (1)Ag2.77 (4)Pb10.23 (4)Sb10.89 (5)S28.00 (5)] crystallizes as a twofold superstructure with P21/n symmetry and pseudo-orthorhombic metrics [a = 8.1882 (3) Å, b = 27.2641 (7) Å, c = 22.8679 (7) Å, β = 90.293 (3)°, V = 5105.0 (3) Å3, Z = 4]. Owyheeite is systematically twinned by reflection at (021) or equivalently (021). Twinning is explained by describing a simplified Pmcn archetype structure as polytype built of two kinds of rods, which contact via electron-pair micelles. A procedure of generating hypothetical polytypes by tiling space with partially overlapping equivalent regions is described.

Prachařite, ideally CaSb5+2(As3+2O5)2O2·10H2O, is a new mineral found in underground workings of the Plaka Mine No. 80, Plaka, Lavrion Mining District, Attica, Greece. It occurs as colourless to white, thin tabular hexagonal, in general sharp crystals up to 2.5 mm in diameter, and is associated with pharmacolite, sulphur and very rare smamite Ca2Sb(OH)4[H(AsO4)2]·6H2O on a matrix composed of sphalerite, galena and carbonate gangue. Prachařite is translucent to transparent, with a glassy lustre, white streak, a good cleavage parallel to 0001 and a distinct cleavage parallel to 10 1 0. It is non-luminescent, brittle, and has an uneven fracture, a Mohs hardness of 2–2.5 and X-ray density Dx = 2.848 g/cm3, Dcalc. = 2.836–2.853 g/cm3 (for two measured compositions). Optically, it is uniaxial negative, with ω = 1.619(1) and ε = 1.553(1). Prachařite is trigonal, space group P 3 c1 (no. 165), with a = 13.951(2), c = 19.899(2) Å, V = 3354.1(10) Å3 and Z = 6. Strongest lines in the X-ray powder diffraction pattern are [d in Å (I) hkl]: 9.894 (100) 002; 6.045 (8) 200; 5.156 (10) 202; 4.946 (11) 004; 3.297 (19) 311, 006, 222; 2.988 (22) 400, 313, 116. Two sets of independent electron probe micro-analyses yielded (wt

Saccoite, Ca2Mn23+F(OH)(8)center dot 0.5(SO4), is a new mineral found at the N'Chwaning III mine, Kalahari Manganese Field, Northern Cape Province, Republic of South Africa. It occurs as fillings of voids in hydrothermally altered manganese ore (comprising mostly of bixbyite and baryte). Further associated minor minerals are braunite, gypsum, chlorite, sturmanite and ettringite. Saccoite forms small needles, felted crystal masses or crusts. The new mineral is olive green, transparent, with white streak and vitreous lustre. No luminescence is observed. Saccoite is uniaxial (-) with refractive indices at 589(1) nm of omega = 1.705(5) and epsilon = 1.684(2). Pleochroism is distinct, i.e. bluish green (omega) and yellowish green (epsilon). The chemical composition was studied by means of an electron probe micro-analyser (EPMA) using wavelength-dispersive X-ray spectrometry (WDS). The empirical mineral formula is Ca2.06Mn1.783+Cu0.10Mg0.07F0.97(OH)(8.02)(SO4)(0.39). The unit-cell dimensions of saccoite (space group P4/ncc) are a = 12.834(3) angstrom, c = 5.622(2) angstrom, V = 926.0(4) angstrom(3)), and the calculated mass density is 2.73 g.cm(-3). Saccoite exhibits a heteropolyhedral framework structure that is composed of edge- and corner sharing CaF2(OH)(6) and M(OH)(6) polyhedra (M= Mn3+ and Cu2+) with large channels along [001], which host disordered and only partially occupied groups, especially SO42-. The hydrogen atoms of the OH groups point into the channel to form hydrogen bonds with the channel anions. Ca-F distances are similar to 2.3 angstrom, the Ca-OH distances in the range of 2.44-2.58 angstrom, and the M(OH)(6) octahedron is strongly 4+2 Jahn-Teller distorted (4 x similar to 1.92 angstrom, 2 x 2.27 angstrom). The F atom is tetrahedrally coordinated to calcium atoms. The strongest lines in the powder X-ray diffraction pattern [d in angstrom (relative intensity) (hkl)] are: 9.0735 (35) (110), 4.5370 (95) (220), 4.0644 (20) (310), 3.0105 (100) (321), 2.8117 (20) (002), 2.7242 (75) (411), 1.9755 (35) (611), and 1.8142 (20) (550).

AbstractSaccoite, Ca2Mn3+2F(OH)8⋅0.5(SO4), is a new mineral found at the N'Chwaning III mine, Kalahari Manganese Field, Northern Cape Province, Republic of South Africa. It occurs as fillings of voids in hydrothermally altered manganese ore (comprising mostly of bixbyite and baryte). Further associated minor minerals are braunite, gypsum, chlorite, sturmanite and ettringite. Saccoite forms small needles, felted crystal masses or crusts. The new mineral is olive green, transparent, with white streak and vitreous lustre. No luminescence is observed. Saccoite is uniaxial (–) with refractive indices at 589(1) nm of ω = 1.705(5) and ɛ = 1.684(2). Pleochroism is distinct, i.e. bluish green (ω) and yellowish green (ɛ). The chemical composition was studied by means of an electron probe micro-analyser (EPMA) using wavelength-dispersive X-ray spectrometry (WDS). The empirical mineral formula is Ca2.06Mn3+1.78Cu0.10Mg0.07F0.97(OH)8.02(SO4)0.39. The unit-cell dimensions of saccoite (space group P4/ncc) are a = 12.834(3) Å, c = 5.622(2) Å, V = 926.0(4) Å3), and the calculated mass density is 2.73 g⋅cm–3. Saccoite exhibits a heteropolyhedral framework structure that is composed of edge- and corner sharing CaF2(OH)6 and M(OH)6 polyhedra (M = Mn3+ and Cu2+) with large channels along [001], which host disordered and only partially occupied groups, especially SO42–. The hydrogen atoms of the OH groups point into the channel to form hydrogen bonds with the channel anions. Ca–F distances are ~2.3 Å, the Ca–OH distances in the range of 2.44–2.58 Ǻ, and the M(OH)6 octahedron is strongly 4+2 Jahn-Teller distorted (4 × ~1.92 Å, 2 × 2.27 Å). The F atom is tetrahedrally coordinated to calcium atoms. The strongest lines in the powder X-ray diffraction pattern [d in Å (relative intensity) (hkl)] are: 9.0735 (35) (110), 4.5370 (95) (220), 4.0644 (20) (310), 3.0105 (100) (321), 2.8117 (20) (002), 2.7242 (75) (411), 1.9755 (35) (611), and 1.8142 (20) (550).

ORDINARY CHONDRITE. I. Baziotis, L. Ferrière, P. D. Asimow, M. Anand, S. Xydous, A. Papoutsa, and D. Topa. Department of Natural Resources Management & Agricultural Engineering, Agricultural Univ. of Athens, Iera Odos 75, 11855 Athens, Greece, ibaziotis@aua.gr, Natural History Museum, Burgring 7, A-1010 Vienna, Austria, California Institute of Technology, Division of Geological & Planetary Sciences, Pasadena, California 91125, USA, Planetary & Space Sciences, The Open University, Milton Keynes MK7 6AA, UK.

This dataset contains the raw unprocessed experimental data for the "Coherent light emission in cathodoluminescence when using GaAs in a scanning (transmission) electron microscope" by Michael Stöger-Pollach et al., Ultramicroscopy 224 (2021) 113260.