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 Gas-mediated trace element incorporation into rhyolite-hosted topaz: A synchrotron microbeam XAS study https://doi.org/10.2138/am-2022-8417 Schaub et al. conducted synchrotron microbeam XAS analysis on picogram quantities of As, Mn, Ga, Ge, Fe, and Ti in topaz crystals from vesicular topaz rhyolite (Thomas Range, Utah) and obtained information on valence state, site assignments, and structural accommodation of these substituents. This information, coupled with trace-element abundances, provides new insights into the nature of the high-temperature magmatic gas involved in topaz formation. Evidence for abundant organic matter in a Neoarchean banded iron formation https://doi.org/10.2138/am-2023-8927 Peng et al. investigated the mineral associations, major element concentrations, total carbon contents and carbon isotope compositions of a set of BIF samples with highly variable iron and TOC contents from the late Neoarchean Zhalanzhangzi BIF, China. The results show that graphite grains with crystallization temperatures comparable to that predicted for the regional metamorphic grade are widely distributed despite highly variable iron and total organic carbon contents. The graphite is interpreted to represent the metamorphosed product of syngenetic biomass based on its co-occurrence with apatite rosettes and negative bulk rock ��13C organic values. The close association of graphite with iron-bearing phases indicates that ferric (oxyhydr)oxides may have exerted a first-order control on the abundance of OM. A dunite fragment in meteorite northwest Africa (NWA) 11421: A piece of the moon's mantle https://doi.org/10.2138/am-2022-8911 Treiman and Semprich describe a centimeter-sized fragment of dunite, the first recognized fragment of Moon mantle material, in the lunar highlands breccia meteorite Northwest Africa. From electron microscope data on dunite, they derive inferences about the bulk composition of the lunar mantle, processes related to the Lunar Magma Ocean and gravitational overturn of its cumulate rocks, and the present-day thermal structure of the Moon's mantle. Electrical properties of iron sulfide-bearing dunite under pressure: Effect of temperature, composition, and annealing time https://doi.org/10.2138/am-2023-9054 Tauber et al. report electrical measurements of a mantle xenolith with varying amounts of metal sulfide compounds over a wide frequency range while under high pressure and temperature. Samples annealing at 1023 K is found to significantly affect the electrical response at temperatures up to ~1100 K. Iron-sulfur compounds strongly increase bulk conductivity at or above 6.5%. At this threshold, the molten iron-sulfur network is fragile. Samples with added Ni or Fe metal show lowered conductivities relative to the dunite host. This surprising behavior is likely caused by a lowered oxygen fugacity. Hydrogen bond symmetrization and high-spin to low-spin transition of ��-FeOOH at the pressure of Earth's lower mantle https://doi.org/10.2138/am-2022-8839 Insixiengmay and Stixrude conducted density functional theory (DFT) calculations to study ��-FeOOH, the iron-bearing end-member of phase H, which is the dominant hydrous phase at lower mantle conditions. This phase exhibits rich behavior and serves as a model system for understanding two transitions that occur in a variety of Earth materials at high pressure: hydrogen bond symmetrization and a high-spin to low-spin transition. The authors examine the change in physical properties across each transition and explore implications for their possible effects on geophysical probes by looking at changes in seismic wave velocity and electrical conductivity. CURIES: Compendium of uranium Raman and infrared experimental spectra https://doi.org/10.2138/am-2022-8738 No single database of Raman and IR spectra exists for uranium materials exclusively, and no large-scale summary of other important signatures originating from structural features beyond the axial U-O bond and other U-O moieties has been tabulated. Spano et al. provide new insights into Raman and infrared spectral features that are indicative of the underlying structural attributes from which they originate. The authors perform an extensive survey of all available experimental Raman and infrared spectra for supergene uranium minerals and employ multivariate statistical analyses to determine spectroscopic features that are common to groups of uranyl minerals based on secondary chemistry. S2- and S3-radicals and the S42- polysulfide ion in lazurite, ha��yne, and synthetic ultramarine blue revealed by resonance Raman spectroscopy https://doi.org/10.2138/am-2022-8655 Farsang et al. demonstrated the power of resonance Raman spectroscopy in search for sulfur species trapped in the cages of feldspathoids. The S42- polysulfide ion is reported in lazurite and ha��yne for the first time. The results have implications in a broad range of fields, e.g., chemistry (identifying trace amounts of S-species), optoelectronics (entrapping S42- into sodalites/zeolites), and arts (identifying the provenance of natural ultramarines). Effect of faceting on olivine wetting properties https://doi.org/10.2138/am-2022-8808 Huang et al. evaluated facet-bearing dihedral angles and their proportions in olivine�Cmulticomponent aqueous fluid systems. The results show that: (1) faceting produces larger dihedral angles than those with curved interfaces in the olivine-fluid system; (2) grain boundary planes are frequently composed of low-index planes, and the facet-facet angles are explained by olivine crystallography; and (3) the facet proportion is consistent with electrical conductivity data; faceting effects could be magnified under sheared mantle. The obscuring effect of magma recharge on the connection of volcanic-plutonic rocks https://doi.org/10.2138/am-2022-8642 The plutonic and volcanic realms are connected through the extraction of crystal-poor rhyolites from batholithic crystal mushes, whereas big data analyses of global volcanic and plutonic rocks reveal little evidence for significant segregation of liquids from plutons. Zhao et al. explore the possibility that magma recharge obscures the records of liquid-crystal segregation and remind us that big data analysis should be done with caution to avoid biased results. In-situ study of microstructures induced by the olivine to wadsleyite transformation at conditions of the 410 km depth discontinuity https://doi.org/10.2138/am-2022-8731 Olivine transforms to wadsleyite at the conditions of 410 km depth in the Earth's mantle. How does this transformation affect microstructures and grain orientations? Ledoux et al. used in-situ experiments and followed the orientations of individual crystallites as the transformation proceeded. They do not observe relationships between the parent olivine and daughter wadsleyite phases and hence conclude that, in the Earth's mantle, microstructures should be reset below the 410 km depth discontinuity. Effect of pre-existing crystals and melt homogeneity on the decompression-induced crystallization of hydrous rhyodacite magma https://doi.org/10.2138/am-2022-8723 Magma crystallization controls its rheology and volcanic eruption. Matsumoto et al. investigated the effect of pre-existing crystals and melt homogeneity on magma crystallization during decompression. The results indicate that the injection of high-temperature magma into the reservoir that changes pre-existing crystals and melt homogeneity may control crystal texture formed during magma ascent and volcanic eruption. Origin of clinopyroxene-ilmenite symplectites in mafic granulites from eastern parts of the Chotanagpur granite gneissic complex, East Indian shield https://doi.org/10.2138/am-2022-8715 Chatterjee et al. report a rare occurrence of rod-like intergrowths of clinopyroxene-ilmenite that variably replace titanite in a suite of high-pressure mafic granulites from the Chotanagpur Granite Gneissic Complex, Eastern Indian Shield. The authors have modeled the reaction texture of clinopyroxene-ilmenite symplectite and deduced the physical condition of metamorphism. The clinopyroxene-ilmenite symplectites formed at the expense of garnet and titanite during steep near isothermal decompression (from ~13 kbar to ~7 kbar, at ~800��C), in the presence of fluid phase. It is also demonstrated that relative to Fe, Mg, and Ca, Ti was less mobile and that the mobility of Ti was restricted within the confines of the titanite being replaced by the clinopyroxene-ilmenite symplectite. Limited mobility of Ti even in the presence of presumed F-Cl bearing fluids or melt has important implications on the Ti mobility in the deep continental crust. Single-crystal analysis of La-doped pyromorphite (Pb5(PO4)3Cl) https://doi.org/10.2138/am-2022-8664 Sordyl et al. synthesized two La-doped pyromorphite analogs (Pb5(PO4)3Cl) and two control samples (with the absence of La) from aqueous solutions at 25��C. Na+ and K+ were used as charge compensating ions to facilitate the incorporation of trivalent REE cations (La3+ + Na+ * 2Pb2+ and La3+ + K+ * 2Pb2+). The extent of La substitution, the position of La in the structure and the induced structural changes were determined using single-crystal X-ray diffraction. The results have applications in both fundamental understanding of apatite structure and environmental mineralogy (mineral-water interactions). Moreover, the results extend our knowledge of geofunctional materials that may be useful in future applications of Pb-apatite in REE recovery. Crystal structure of calcium-ferrite type NaAlSiO4 up to 45 GPa https://doi.org/10.2138/am-2022-8432 Alkali-rich aluminous high-pressure phases including calcium-ferrite (CF) type NaAlSiO4 in MORB composition are thought to constitute ~20% by volume in the lower mantle. Qin et al. investigated the Fe-free and Fe-bearing CF phases using single-crystal synchrotron X-ray diffraction and Raman spectroscopy coupled with diamond anvil cells up to 45 GPa. The Fe-free and Fe-bearing CF samples display similar compressibility and roughly 2% more compressible than the CF-type MgAl2O4. Compared to jadeite, the ability of CF-type phases to contain incompatible elements such as Na up to lower mantle pressures requires the larger and less compressible NaO8 polyhedra. These data provide new knowledge on how large alkali metals can be hosted in aluminosilicate framework structures with stability well into the lowermost mantle. Revision of the CaMgSi2O6�CCO2 P-T phase diagram at 3-6 GPa https://doi.org/10.2138/am-2022-8588 Reactions involving CO2 and carbonates are the key factors determining the magma generation in the upper mantle and the deep carbon cycle. The CaO-MgO-SiO2-CO2 system is important for studying these reactions. Shatskiy et al. investigated the impact of carbonatization on the mafic suit solidus (the system diopside-CO2) in the range of 3�C6 GPa and 850�C1500 ��C. They found that above 4.5 GPa, the liquidus reaction involving clinopyroxene and CO2 sweeps down through 350 ��C via a pressure maximum near 5.3 GPa to meet the invariant point at 4.5 GPa. The shape of the solidus resembles that of lherzolite�CCO2 but shifted by 2 GPa to higher pressures. ___ Rachel Russell Managing Editor, American Mineralogist rrussell@minsocam.org Am Min Website, including Information for Authors and Tab to Permissions: http://www.minsocam.org/msa/AmMin/AmMineral.html Join MSA: https://msa.minsocam.org/membership.html (hint: members get free online color in Am Min) New Main MSA Website view: https://msaweb.org/ Because of changes in Outlook365, we are having trouble emailing "gmail" client users. Thank you in advance for patience. Holiday/Vacation/Out of Office/etc.: Nov 15, 21, 24, Dec 1 - 6, Dec 25 - 26