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We report the first discoveries of high-pressure minerals in the historical L6 chondrite fall Château-Renard, based on co-located Raman spectroscopy, scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy and electron backscatter diffraction, electron microprobe analysis, and transmission electron microscopy (TEM) with selected-area electron diffraction. A single polished section contains a network of melt veins from ~40 to ~200 μm wide, with no cross-cutting features requiring multiple vein generations. We find high-pressure minerals in veins greater than ~50 μm wide, including assemblages of ringwoodite + wadsleyite, ringwoodite + wadsleyite + majorite-pyrope ss , and ahrensite + wadsleyite. In association with ahrensite + wadsleyite at both SEM and TEM scale, we find a sodic pyroxene whose Raman spectrum is indistinguishable from that of jadeite but whose composition and structure are those of omphacite. We discuss constraints on the impact record of this meteorite and the L-chondrites in general.

The volcanic section of the Manipur Ophiolite (MO), representing the crustal portion of the Neo-Tethyan oceanic lithosphere occurs as basalt, basaltic trachyandesite, and dacite in the Gamnom-Phangrei sector, Manipur, at 25°01′N–25°09′N and 94°24′E–94°27′E. They associate with cherts and ultramafics. The clinopyroxene compositions of basalt and basaltic trachyandesite, obtained through electron microprobe analyzer, were used as a petrogenetic indicator to identify the parent magma-types and their tectonic settings. Based on the variable content of major oxides, they are classified as high- and low-Ti clinopyroxenes. High Ti and Al contents with relatively lower silica saturation are observed in the former group and vice versa in the latter. The Ti D Cpx/rock values in low- and high-Ti clinopyroxene are comparable with island-arc basaltic andesite and MORB, respectively, which confirms that the clinopyroxene composition is primarily related to the host magma-type and its tectonic setting. Clinopyroxene thermometry (ranging 1150–605 °C) suggests progressive differentiation of the parent magmas. Several bivariate and tectonic discrimination diagrams depict MORB (non-orogenic setting) and island-arc boninitic magma affinities (orogenic setting) for the high- and low-Ti clinopyroxenes, respectively. The coexistence of both MORB and island-arc boninitic magma-types in the volcanic section of Manipur Ophiolite as characterized by their varying Ti, Al, and Si contents may indicate either juxtaposition of rocks formed in diverse tectonic settings (i.e., due to transformation of tectonic setting from mid-ocean ridge to supra-subduction zone) or, a change in magma composition in a subduction zone setting. However, field relationships coupled with the mineral–chemical signatures implies a supra-subduction zone setting for the evolution of the crustal section of MO.

A multi-methodological study was conducted in order to provide further insight into the structural and compositional complexity of rare earth element (REE) fluorcarbonates, with particular attention to their correct assignment to a mineral species. Polycrystals from La Pita Mine, Municipality de Maripí, Boyacá Department, Colombia, show syntaxic intergrowth of parisite–(Ce) with röntgenite–(Ce) and a phase which is assigned to B3S4 (i.e., bastnäsite-3–synchisite-4; still unnamed) fluorcarbonate. Transmission electron microscope (TEM) images reveal well-ordered stacking patterns of two monoclinic polytypes of parisite–(Ce) as well as heavily disordered layer sequences with varying lattice fringe spacings. The crystal structure refinement from single crystal X-ray diffraction data – impeded by twinning, complex stacking patterns, sequential and compositional faults – indicates that the dominant parisite–(Ce) polytype M1 has space group Cc. Parisite–(Ce), the B3S4 phase and röntgenite–(Ce) show different BSE intensities from high to low. Raman spectroscopic analyses of parisite–(Ce), the B3S4 phase and röntgenite–(Ce) reveal different intensity ratios of the three symmetric CO3 stretching bands at around 1100 cm−1. We propose to non-destructively differentiate parisite–(Ce) and röntgenite–(Ce) by their 1092 cm−1 / 1081 cm−1 ν1(CO3) band height ratio.

Keutschite, Cu.sub.2 AgAsS.sub.4, 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) Ã, V=312.40(14) Ã.sup.3, a:b:c=1:1:0.897, and Z=2. The crystal structure was refined to R.sub.1 =0.0199 for 286 reflections with I3Ï(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 à (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 Cu.sub.2.05 Ag.sub.0.96 (As.sub.0.95 Sb.sub.0.04).sub.Σ0.99 S.sub.4.00 (based on eight atoms). The ideal formula, derived from the crystal structure, is Cu.sub.2 AgAsS.sub.4 . The name honours Frank Keutsch (born 1971) for his contribution to the mineralogy of the Uchucchacua deposit.

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.

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.

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).

Spaltiite is a new thallium sulfosalt with the ideal formula of Tl.sub.2 Cu.sub.2 As.sub.2 S.sub.5 . 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 â¼0.2 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 (VHN.sub.15 ranges from 30 to 65, mean 47 kg mm.sup.-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 Tl.sub.1.94 Cu.sub.2.04 Ag.sub.0.01 As.sub.1.95 Sb.sub.0.03 S.sub.5.03, 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) Ã, β=99.25(8)°, V=985.5(8) Ã.sup.3). The crystal structure was determined from single-crystal X-ray diffraction data (R.sub.1 =12.18 % for 4753 data, with F.sub.o >4Ï (F.sub.o) 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 à (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 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.

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) Å, α= 96.001(2), β= 116.615(2), γ= 95.372(2)°, and V = 11721.7(6) Å3. 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.