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 https://msaweb.org/MSA/AmMin/ and click the “Editor’s Notes” tab, which will be available shortly after the issue is live. 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 an MSA membership, authenticate your login from the American Mineralogist website at http://www.msapubs.org/. On the portal page, click the American Mineralogist link and enter your username (e-mail address) and your password (membership number). Then, search for the paper you want to read via your browser's search tools. (On most PCs, it is control-F, but that may vary for you.) Note that on GSW, you can sign up for a table of contents to be sent to you when the issue is live -- this feature is available to anyone who registers on the site. Thank you for reading American Mineralogist. Sincerely, Fabrizio Nestola Paul Tomascak Chief Editors, American Mineralogist American Mineralogist Volume 111; Number 11; 11-01-2026 Spatial and Temporal Variations in Scheelite Composition Record Fluid Evolution Pathways in the Yongping Cu-W Skarn Deposit, South China Guiqing Xie, Yunhao Ji, Mathias Burisch, Xiaohui Chen, Xunjun Wang, Xiaoyu Shang This study uses the chemistry and isotopes of scheelite from the Yongping Cu-W skarn deposit to understand how ore-forming fluids evolved from proximal to distal zones. Trace element and Sr isotope trends reflect changes in temperature, pH, and fluid-rock interaction, offering insights into hydrothermal processes and practical vectors for tungsten exploration. https://doi.org/10.2138/am-2025-10000 Reactions between carbonatitic melt and syenitic wall rocks drive REE mineralization in the Maoniuping deposit, southwest China Yihang Gao, Xu Zheng, Aleksandr Stepanov, Yan Liu The origin of carbonatite-related REE deposits (hydrothermal vs. magmatic) is a hot topic globally, with limited natural case studies for magmatic origin. The world-class Oligocene Maoniuping deposit preserves an intact magmatic-hydrothermal process to delineate the genesis of such deposits. Initially, metasomatism between evolved carbonatite melt and syenite causes crystallization of titanite, bastnäsite, apatite, and alkali silicates. Subsequent hydrothermal overprinting, evidenced by apatite dissolution with bastnäsite overgrowth, only caused localized REE redistribution without reserve upgrade. https://doi.org/10.2138/am-2025-10004 Modraite, Ca19Fe2+Al4(Al7Fe2+)(SiO4)10(Si2O7)4O(OH)9, a new vesuvianite-group mineral from the Modra skarn,Malé Karpaty Mountains, Slovakia Pavel Uher, Peter Bačík, Olena Rybnikova, Manfred Wildner, Marcel Miglierini, Eugen Libowitzky, Lenka Skřápková, Radek Škoda, Tomáš Vaculovič, Martin Ondrejka, Bronislava Voleková, Ľubica Puškelová, Sergii Kurylo, Tomáš Mikuš The paper includes a description of modraite, a new mineral and a member of the vesuvianite group, named after the locality in western Slovakia. Modraite contains dominant divalent iron in both the five-coordinated Y1 structural site and the octahedral Y3 site. This discovery significantly enriches our knowledge concerning compositional variations of the vesuvianite group under high-temperature contact metamorphic conditions. https://doi.org/10.2138/am-2025-10007 Raman Spectroscopy and Lattice Dynamics Calculations of Two Fe2+ Silicate Minerals: Pellyite and Grandidierite David McKeown Raman measurements and lattice dynamics calculations were performed on the Fe2+-silicates pellyite and grandidierite, providing vibrational assignments to spectral features, with the motivation to determine Fe-site contributions. For pellyite, significant tetrahedral Fe2+O4 contributions can be correlated to two prominent 386 and 425 cm–1 peaks, near the 410 cm–1 Fe2+-related feature observed in some borosilicate glasses. However, no such FeO5-site mode correlations can be made for grandidierite. https://doi.org/10.2138/am-2025-10012 Determination of Fe oxidation state in tourmaline with the flank method by electron probe microanalysis Dongmei Qi, Chao Zhang, Haoyang Yuan, Tai Wen, Xiaoyan Li, Peng Liu, Lining Cheng, Philip Wiegel, Renat Almeev Iron is the most abundant multivalent element on the Earth, and its oxidation state in minerals may provide important constraints on oxygen fugacity. In this paper, Qi et al. present an analytical method using an electron microprobe and necessary reference materials for measuring Fe oxidation state in tourmaline at the micrometer scale. They obtain linear correlations between Fe oxidation state and Fe Lβ/Lα intensity ratios, concluding that Fe3+/ΣFe can be quantified to better than ±0.1. https://doi.org/10.2138/am-2025-10018 Hydrothermal alteration of xenotime-(Y) and samarskite-(Y) in highly fractionated granites: Implications for the formation of ion-adsorption HREE deposits Heng Wang, Wu-bin Yang, Zhi-Wei Bao, Xiaoliang Liang, Hongping He, Wei Tan, Jianxi Zhu Hydrothermal fluids disrupt the primary structures of xenotime-(Y) and samarskite-(Y), leading to the generation of abundant structural defects in the altered domains. This implies that xenotime-(Y) and samarskite-(Y) altered by hydrothermal fluids can serve as potential sources of ion-exchangeable HREEs in the weathering crusts, thereby expanding the source spectrum for ion-adsorption HREE deposits. https://doi.org/10.2138/am-2025-10020 Contrasting whole-rock geochemistry and mineralogy of REE- and U-fertile granites: Implications for the formation of regolith-hosted REE and granite-related U deposits Long Zhang, Fangyue Wang, Taofa Zhou, Zhenyu Chen This study provides new insights into whole-rock geochemical and mineralogical controls on the genetic link between granites and regolith-hosted REE and granite-related U deposits. Regolith-hosted REE and granite-related U deposits are generally related to granites with specific geochemical fingerprints. Uranium-rich low-Ca peraluminous granites with U/(REE + Y) >~0.2 should be considered as high-priority targets for exploration for granite-related uranium deposits. High-Si and low-Ca granites with the LREE/(HREE + Y) ratio of <~3, commonly characterized by the association of HREE-Y-rich minerals such as synchysite-(Y) and gadolinite-(Y), may have greater regolith-hosted HREE ore potential. High-Ca granites (CaO >1 wt%) with an LREE/(HREE + Y) ratio of >~1.5, in which allanite and titanite are the major REE carriers, will have greater LREE ore potential. https://doi.org/10.2138/am-2025-10024 Scandium enrichment and release in pyroxene driven by melt and fluid metasomatism: Insights from East Gondwana, Antarctica Shanshan Li, Bing Li, Youhong Sun, Jun Deng, German Leitchenkov, Kristoffer Szilas, David Hernández-Uribe, Pavel Talalay, Nan Zhang, Xiaopeng Fan, Yazhou Li, Da Gong, Yizi Zou, Jinhua Li, Kunfeng Qiu This study investigates Sc enrichment and release in pyroxene from charnockites and mafic granulites in East Antarctica's Prydz Bay Belt. Reduced carbonatite melts enriched Sc in pyroxene through mantle metasomatism, followed by decompression melting that triggered Sc release via metasomatism by oxidized silicate melts. Subsequent arc accretion involved interaction with an external, oxidized, and likely phosphorus-rich aqueous fluid, leading to further Sc release. The widespread occurrence of pyroxenes and CO2-rich inclusions suggests regional-scale Sc enrichment. https://doi.org/10.2138/am-2025-10035 Synthesis of critical-element-bearing olivine and pyroxene Zoltan Váci, Jennifer Houghton, Michael Krawczynski, Helene Couvy, Kelly Peterson, John Loring, David Fike, Young-Shin Jun Nickel and cobalt are considered to be too low in concentration in silicate minerals to be extracted efficiently. However, with increasing need for these critical elements, the development of novel extraction methods is necessary. To this end, Váci et al. synthesized Ni- and Co-bearing olivine and pyroxene in large batches to serve as starting materials for future extraction experiments. The resulting chemical and mineralogical data characterize the synthetic minerals and model sources of impurities. https://doi.org/10.2138/am-2025-10036 Symplectitic intergrowths enriched in low-melting-point chalcophile elements and their implications for gold enrichment in the Dadiangou gold deposit, western Qinling Orogen, Central China Bin Zhang, Jiajun Liu, Jeffrey Fourestier, Ruirong Cao, Zhao Lai, Baisong Du, Mingyang Si, Guoming Weng Low-melting-point chalcophile elements (LMCEs; Te, Bi, Pb, Sb) exhibit a strong affinity for S and Au, serving as critical agents that facilitate the efficient enrichment and precipitation of Au in hydrothermal systems. In this study, Zhang et al. investigate symplectitic intergrowths of LMCE- and Au-bearing minerals from the Dadiangou Au deposit in the western Qinling Orogen, central China. Three types of symplectites were interpreted to form through melt-fluid immiscibility, dislocation-mediated interfacial re-equilibration (DMIR), and coupled dissolution-reprecipitation (CDR). Thermodynamic phase diagrams indicate that Pb-Bi-Te melts can persist in hydrothermal fluids, sequester precious metals, and subsequently release them in response to variations in f(Te2) and f(S2), rather than temperature. These findings suggest that LMCE melts may represent a widespread mechanism for Au enrichment in orogenic and other Au deposits worldwide. https://doi.org/10.2138/am-2025-10037 The Raman Spectra Database (RSDB): A Curated and Managed Raman Reference Database for Mineral Identification Paul Bartholomew, Jeffrey Post, Robert Downs, Thomas Blanton, Soorya Kabekkodu, Justin Blanton Geoscientists worldwide increasingly use Raman spectroscopy for routine mineral identification, which amplifies the need for a reference Raman database that is not only high-quality and curated for mineral identification, but also has institutional commitment for continuous growth and long-term availability. Bartholomew et al. have created such a database (RSDB) with all of these criteria in mind. Guided by the objective to support most geoscientists immediately, the initial release has been populated by combining reference spectra curated from the RRUFF database with hundreds of new, high-quality spectra. The result is managed and distributed by the International Centre for Diffraction Data, which will ensure continued growth and longevity. https://doi.org/10.2138/am-2025-10048 Activation of slip systems in Sn-bearing sphalerite and its consequences for trace element mobility during fluid-assisted overprinting Jing Xu, Samuel King, Cristiana Ciobanu, Nigel Cook, Ashley Slattery, Taiping Zhao, Bo Xing Disrupted patterns of chemical oscillatory zoning were examined across a Sn-bearing sphalerite. Activation of two distinct slip systems, {101} and {111}, at ~300 °C is characterized by dislocation glide and creep, respectively. Tin is preserved in {101} slip domains, yet {111} slip causes complete and potentially rapid Sn removal. Results emphasize that the observed features could have been generated at far shorter timeframes than often believed. https://doi.org/10.2138/am-2026-10198 Nanoscale study of cobaltite in pyrite: insights and significance Lei Yan, Yu Fan, Jun Huang, Yifan Zhang, Tong Zuo, Fangyue Wang, Taofa Zhou In this muti-tool study, nanoscale cobaltite is identified in pyrite from Longqiao Co-bearing skarn deposit, sharing the same crystal orientation as the host pyrite. Cobalt migration in pyrite is dominated by fluid-induced solid-state lattice diffusion. Formation of nanoscale cobaltite consumes Co from adjacent pyrite and fluid, explaining the micrometer-scale heterogeneous distribution of cobalt. Microscale chemical zoning in pyrite can result from a single diffusion-controlled process and does not necessarily require multiple fluid pulses or later overprinting. https://doi.org/10.2138/am-2025-9829 ------------------------- American Mineralogist Mineralogical Society of America (MSA) Chantilly, VA 20151 editorial@minsocam.org<mailto:editorial@minsocam.org> Website: https://msaweb.org/MSA/AmMin/