Dear Colleagues, We currently have a Denton Vacuum Turbo Bench Top C coater at the AMNH, for which we encounter various problems: it is very inconsistent in its coating (sometimes it works directly, sometimes after 5 runs), and the piece holding the carbon rod is likely melting, getting an oval shape, and making the insertion of the rod impossible. We replaced the rod holder during the summer, and it’s already oval. Did any of you have similar issues? If yes, what did you do to fix them? We are also considering buying a new device, as the coater is used daily. Any advice on C coater that can handle heavy usage? Thanks for your help, Celine Celine Martin PhD Research Scientist and Laboratory Manager American Museum of Natural History Central Park West at 79th Street New York, NY 10024-5192, USA Phone: (+1) 212 769 5380; Fax: (+1) 212 769 5533 Email: cmartin@amnh.org<mailto:cmartin@amnh.org>

Dear American Mineralogist Readers, Below are the Paper Highlights for this month’s issue of the American Mineralogist: International Journal of Earth and Planetary Materials. You may also view the American Mineralogist Paper Highlights list at here (http://www.minsocam.org/MSA/Ammin/AM_NotableArticles.html). The DOI links below will take you to the abstract on GeoScienceWorld. If you have “IP” access via your institution’s library, it should reveal the whole paper. Consult your institution’s IT department or friendly librarian. If you have MSA membership, then authenticate in from the American Mineralogist menu (here<http://www.msapubs.org/> directly). Once at the portal page, click the right-side American Mineralogist link, enter your user name (e-mail address), and your password (membership number). Then search via your browser’s search tools for the paper you want to read. (On Rachel’s computer, it is control-f but we think that is little different for everyone.) Note that on GSW you can sign up for a table of contents to be sent you when the issue is live -- this is a feature open to anyone who registers on the site. Thank you for reading American Mineralogist. Sincerely, Hongwu Xu Don Baker Highlights and Breakthroughs: Oxidation of arcs and mantle wedges: It’s not all about iron and water https://doi.org/10.2138/am-2022-8802 Callum Hetherington wrote a commentary on Song et al. (2022)<https://doi.org/10.2138/am-2022-8171> Oxidation of arcs and mantle wedges by reduction of manganese in pelagic sediments during seafloor subduction. American Mineralogist, 107, 1850-1857. Paragenesis of Li minerals in the Nanyangshan rare-metal pegmatite, Northern China: Toward a generalized sequence of Li crystallization in Li-Cs-Ta-type granitic pegmatites https://doi.org/10.2138/am-2022-8285 Yang et al. describe a generalized crystallization sequence of lithium minerals in LCT-type pegmatites. As the typical and the largest one of hundreds of LCT pegmatite dikes in eastern Qinling orogenic district, North China, the Nanyangshan pegmatite is strongly Li-mineralized with a clear series of lithium minerals, including spodumene, montebrasite, lithiophilite, elbaite, lepidolite, and possible former petalite. They discuss the potential factors (mostly volatile activity) controlling the stability of lithium minerals under conditions of pegmatite crystallization. They collect Li-mineral data of 58 Li-Cs-Ta pegmatites worldwide, which are used to infer a general consensus of successive evolution of Li minerals with crystallization of LCT pegmatites. The new mineral tomiolloite, Al12(Te4+O3)5[(SO3)0.5(SO4)0.5](OH)24: A unique microporous tellurite structure https://doi.org/10.2138/am-2022-8368 Missen et al. describe a new mineral, tomiolloite, which has a unique structure and chemical composition. It was found in the oxidation zone of a tellurium-gold mine near Moctezuma, Sonora, Mexico. Tomiolloite has a microporous structure containing channels. The chemical composition of tomiolloite includes aluminium cations and four anions: the tellurite anion, the sulfate and sulfite anions (unusual to find in the same structure), and hydroxide anions. Authigenic anatase nanoparticles as a proxy for sedimentary environment and porewater pH https://doi.org/10.2138/am-2022-8330 Titanium has long been considered to be immobile during weathering and diagenetic processes, and it is widely used for normalization of elemental concentrations in weathering profiles. However, Hong et al. demonstrate that authigenic titania is commonly formed in fine-grained siliciclastics of a wide variety of facies through weathering of Ti-bearing silicates, authigenic euhedral anatase is present ubiquitously as nanoparticles, and its morphology varies in a predictable manner over a range of depositional environments. The crystal habit of authigenic anatase nanoparticles is controlled primarily by porewater pH during early diagenetic alteration of Ti-bearing silicates. Their findings suggest that authigenic anatase could be a sensitive proxy for the sedimentary environment and sedimentary porewater chemistry and will likely prove useful in depositional facies analysis. Color effects of Cu nanoparticles in Cu-bearing plagioclase feldspars https://doi.org/10.2138/am-2022-8325 This study by Jin et al. bridges the gap between colloidal optics in material science and the color effects in minerals and gemstones. The different colors and pleochroism in Cu-bearing feldspars are explained quantitatively for the first time. The result also has implications for understanding the crystal chemistry of feldspars, as well as the igneous processes that create them, by providing a way to quantify the diffusion of Cu in feldspars through optical spectroscopy. It also inspires designing and engineering novel optical materials. Expanding the speciation of terrestrial molybdenum: Discovery of polekhovskyite, MoNiP2, and insights into the sources of Mo-phosphides in the Dead Sea Transform area https://doi.org/10.2138/am-2022-8261 Britvin et al. describe a new mineral, polekhovskyite, MoNiP2, the first terrestrial Mo phosphide and a phosphorus-rich homologue of meteoritic monipite, MoNiP. Polekhovskyite represents a novel terrestrial Mo speciation. Having 44 wt% Mo in its composition, the mineral is a striking example of selective Mo enrichment. The origin of Mo in phosphides of the Southern Levant is likely related to the processes of the Dead Sea Rift formation. Sound speed and refractive index of amorphous CaSiO3 upon pressure cycling to 40 GPa https://doi.org/10.2138/am-2022-8081 Geballe et al. investigate amorphous silicate, CaSiO3, that is created through several different pressure-temperature routes. The samples exhibit highly reproducible properties at room temperature and at pressures up to 40 GPa, especially in comparison to other silicates. This suggests that the amorphous solid may mimic the liquid over the pressure range investigated. The basis of this assessment is three complementary data sets: sound-speed measurements, refractive index measurements, and previously published NMR and Raman spectroscopy. Calorimetric study of skutterudite (CoAs2.92) and heazlewoodite (Ni3S2) https://doi.org/10.2138/am-2022-8337 Thermodynamic properties of chalcogenide minerals are important for modeling and understanding ore deposits. In particular, nickel and cobalt arsenides, sulfarsenides, and sulfides occur in many hydrothermal ore deposits but their thermodynamic properties of these phases are not well known. Majzlan et al. determined a full set of thermodynamic properties for heazlewoodite and skutterudite using high-temperature oxide-melt solution calorimetry and low-temperature relaxation calorimetry. Melting phase equilibrium relations in the MgSiO3-SiO2 system under high pressures https://doi.org/10.2138/am-2022-8004 Moriguti et al. determined the melting relations in the system MgSiO3-SiO2 at 13.5 GPa and up to 2900 °C using the Kawai-type of multi-anvil apparatus. At such extreme temperatures, generated pressure calibration was also carried out. The mass-balance calculations on E-chondrites model indicate that Si content in the core would be between 2.7 to 8.6 wt%, which is within the range of 2 to 9 wt% Si in the core as predicted by metal-silicate element partitioning. Thus, the E-chondrite model could still have high potential to explain the Bulk Earth composition if the Si depletion in the core has worked well through Earth's history. Effects of hydrostaticity and Mn-substitution on dolomite stability at high pressure https://doi.org/10.2138/am-2022-8248 Wang et al. collected high-pressure Raman spectra of natural Mg-dolomite CaMg(CO3)2 and Mn-dolomite kutnohorite Ca1.11Mn0.89(CO3)2 samples up to 56 GPa at room temperature in a diamond anvil cell using helium or neon as a pressure-transmitting medium (PTM). Phase transitions in CaMg(CO3)2 were observed at 36.1(25) GPa in helium and 35.2(10) GPa in neon PTM for dolomite-II to -III, respectively. Moreover, the onset pressure of Mn-dolomite Ca1.11Mn0.89(CO3)2-III occurs at 23−25 GPa, about 10 GPa lower than that of Mg-dolomite-III. These results reveal a significant effect of hydrostaticity and cationic radius on the kinetics of the pressure-induced structure transformations in the dolomite group. The results provide new insights into deep carbon carriers within the Earth's mantle. Crystallization of bastnaesite and burbankite from carbonatite melt in the system La(CO3)F-CaCO3-Na2CO3 at 100 MPa https://doi.org/10.2138/am-2022-8064 Nikolenko et al. present the first experimental data on the crystallization of bastnaesite and two other REE carbonates, burbankite and lukechangite, from carbonatitic melt in the model system La(CO3)F-CaCO3-Na2CO3 at 100 MPa and temperatures between 625 and 850 ºC. Liquidus phases in the run products are calcite, nyerereite, Na carbonate, bastnaesite and burbankite solid solution and lukechangite. Addition of 10 wt% Ca3(PO4)2 to a ternary mixture resulted in massive crystallization of La-bearing apatite and monazite, and complete disappearance of bastnäsite and burbankite. Thus, primary magmatic crystallization of REE carbonates and fluorocarbonates from natural carbonatitic melts is unlikely (with a possible exception of the uniquely REE-rich and P2O5-poor carbonatites at Mountain Pass). Crystal shapes, triglyphs, and twins in minerals: The case of pyrite https://doi.org/10.2138/am-2022-8280 Arrouvel analyzed pyrite samples using XRD, SEM and EDS coupled with atomistic simulations to study their crystal growth, twinning and anisotropy. The findings include: (1) {120} and {210} pyritohedral pyrite can be distinguished by the orientation of the striations on their surfaces. (2) The striations are linked to kinetic growth with a higher rate. (3) The directions of the striations are compatible to the sulfur network orientated along the 6 <001> directions. (4) The so-called negative striated {120} pyrite crystals are rare specimens that can be encountered in geothermal areas. (5) Striations help identify [uvw]° rotations in merohedral twinning. (6) Simulations confirm that mirror (001) twin and [001]90° iron-cross twinning are energetically the most favorable grain boundaries. Nanostructure reveals REE mineral crystallization mechanisms in granites from a heavy-REE deposit, South China https://doi.org/10.2138/am-2022-8309 Shi et al. report unusual nanostructure of Ce-poor bastnasite-(La,Nd,Y) from the South China granites, whose weathering crusts form HREE deposits. In-situ SRXD and high-resolution TEM analyses show the REE-mineral grew as disordered nanocrystals, and coaligned, nearly coaligned nanoparticle aggregations. They provide a novel nonclassical crystallization by particle attachment, and further support that the HREE-rich mineral precipitation in the parental granites underwent sudden, rapid crystallization in a highly oxidized environment. This work has practical implications for mineral exploration, as it provides criteria for the identification of similar HREE-rich deposits elsewhere. Paratobermorite, Ca4(Al0.5Si0.5)2Si4O16(OH)ž2H2Ož(Caž3H2O), a new tobermorite-supergroup mineral with a novel topological type of the microporous crystal structure https://doi.org/10.2138/am-2022-8284 Pekov et al. discovered a new mineral, paratobermorite, ideally Ca4(Al0.5Si0.5)2Si4O16(OH)ž2H2OžCaž3H2O), a member of the tobermorite supergroup, at the Bazhenovskoe chrysotile asbestos deposit, Central Urals, Russia. Paratobermorite significantly differs in the topology of crystal structure [mutual arrangement of (Si,Al)O4 tetrahedra and Ca polyhedra] from tobermorite and other tobermorite-supergroup minerals. Due to the original structure type and the presence of a significant amount of Al which substitutes Si, paratobermorite can be considered a novel microporous material and a perspective cation-exchanger. Morphological and chemical characterization of secondary carbonates in the Toki granite, central Japan, and the evolution of fluid chemistry https://doi.org/10.2138/am-2022-8229 Yuguchi et al., in serial works (Yuguchi et al., 2015, 2019, 2021, and this study), provide new insights into the mass transfer due to hydrothermal alterations and groundwater-rock interactions. This study focuses on the petrography and mineral chemistry of calcites in the Toki granite, central Japan. It explores the sequential variations in mass transfer during the sub-solidus stages in granite, which were overlooked or not fully appreciated in earlier studies. Characteristics and formation of corundum within syenite in the Yushishan rare metal deposits in the northeastern Tibetan Plateau https://doi.org/10.2138/am-2022-8223 Liu et al. present newly discovered in-situ corundum in syenite and discuss the characteristics, origin, and geological processes of corundum. Abundant mineral inclusions were found and categorized into primary and secondary based on morphological and reacting characteristics. They indicate two geological processes. Trace-element characteristics and oxygen isotopes are also consistent with corundum of magmatic origin. The implication is that corundum crystallized in melts with the involvement of Al-rich and Si-poor crustal material. Hydrogen solubility in FeSi alloy phases at high pressures and temperatures https://doi.org/10.2138/am-2022-8295 Light elements alloying with metallic Fe can greatly affect its properties and play a key role in dynamics of planetary cores. H and Si are two candidate light elements in cores. However, the H storage in the Fe-Si system under relevant pressure and temperature is still unclear. Here Fu et al. found dramatic decrease of H content in FeSi alloys when Si is present. Their experiments indicate that H remains in the structure of FeSi alloys when recovered to 1 bar. The unusual property of FeSiHx alloys will help understand important geochemical processes involving hydrogen in future studies. First evidence of dmisteinbergite (CaAl2Si2O8 polymorph) in high-grade metamorphic rocks https://doi.org/10.2138/am-2022-8505 Wannhoff et al. present the first finding and characterization of dmisteinbergite inside crystallized anatectic melt inclusions (MI) in garnet from three locations on two continents. These MI were originally entrapped inside a garnet growing or recrystallizing in presence of crustal melts during orogenesis continental collision under high T and highly variable P. The work on dmisteinbergite in anatectic MI, combined with previous results reported in literature, helps (a) to identify more precisely which factors and P-T conditions control the formation of this particular polymorph and (b) to better constrain the crystallization behavior of silicate melts in small pores. Overall, these new findings contribute to shed light on high T minerals which increasingly appear to be a common occurrence in the metamorphic evolution of the continental crust. New Mineral Names https://doi.org/10.2138/am-2022-NMN1071218