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 10; 10-01-2026 Sunshuite, FeBi2S4, a new member of the pavonite homologous series from the Jiawula-Chaganbulagen Ag-Pb-Zn ore field, Inner Mongolia, China Kaixuan Hui, Ke-Zhang Qin, Guowu Li, Ningyue Sun, Mingjian Cao, Lihui Jia, Li Ting, Yuan Xue Sunshuite, ideally FeBi2S4, represents the first naturally occurring Fe-end-member of the pavonite homologous series and was found within an intermediate-sulfidation epithermal Ag-Pb-Zn ore field (Inner Mongolia, China). Fe in sunshuite is Fe2+ and, together with its association with pyrrhotite and native bismuth, the new mineral has the potential to serve as an indicator of reducing hydrothermal environments. https://doi.org/10.2138/am-2025-10093 Synthesis of K- and Fe-rich davemaoite Oliver Tschauner, Shichun Huang, Justin Hardin, Michael Michael Petaev, Logan Magad-Weiss, Erinna Tschauner, Melanie White, Ashkan Salamat, Nicholas Dygert, Ping Wang Tschauner et al. show that natural davemaoite, CaSiO3-perovskite, could contain significant amounts of Fe, Al, and Na. Starting from a glass with composition similar to the natural davemaoite, the authors were able to synthetize the CaSiO3-perovskite davemaoite at 22-23 GPa supporting the correlation of Na+K with Ca and ferric Fe in deep mantle rock. https://doi.org/10.2138/am-2026-10284 Electrical conductivity of MgCO3 under thermodynamic conditions of Earth's interior: a first-principles investigation Samuel Santos, João Francisco Filho, Lucy Vitória Assali Ab initio modeling shows that the conductivity of MgCO3 is strongly affected by the thermodynamic conditions of the Earth's interior. Conductivity decreases with pressure and experiences a sharp drop due to the transition from magnesite-I to magnesite-II. This indicates that the mineral has a limited influence on the increase in the electrical conductivity of the lower mantle. https://doi.org/10.2138/am-2024-9719 K+/Na+-smectite indicates a lake 3500 million years ago in Gale crater on Mars Xiaorong Qin, Jianxi Zhu, Hongping He, Yi-Liang Li The extent and persistence of liquid water in Gale crater are central to understanding Mars’ past habitability. Previous interpretations range from a deep, extensive lake to wind-deposited sediments with only transient water bodies. Qin et al. report evidence for a deep lake based on Curiosity’s X-ray diffraction detection of K⁺/Na⁺-smectite between Yellowknife Bay and Glen Torridon. These minerals indicate prolonged standing water, analogous to conditions in terrestrial marine sediments. The findings suggest that habitable conditions persisted in Gale crater until approximately 3.5 billion years ago. https://doi.org/10.2138/am-2025-9781 Iron phyllosilicates: Targeted removal by acid treatment and their differing potential to immobilize aqueous sulfide Spencer Bingham, Peter Solheid, Alon McCormick, R. Lee Penn This study examines a taconite mining byproduct (referred to as MS) containing Fe-rich silicates for its potential in sulfate remediation by immobilizing aqueous sulfide as a solid-phase material. MS contains siderite, greenalite, and stilpnomelane. These minerals show different and significant reactivity towards sulfide. This work highlights the potential use of mining waste materials in environmental remediation and emphasizes the roles of specific mineral phases in sulfide immobilization. https://doi.org/10.2138/am-2025-9800 Fluid assimilation-fractional crystallization drives heavy zinc isotope enrichment in Himalayan leucogranites Cuihua Luo, Gengxin Deng, Shubin Fang, Xiao Chi Liu, Fang Huang Himalayan leucogranites provide key insights into the differentiation of the upper continental crust. The Kampa and Qianjingou leucogranites exhibit elevated δ⁶⁶Zn values (0.29–0.91‰) that cannot be explained by partial melting or fractional crystallization alone. A fluid assimilation–fractional crystallization (FAFC) model explains this enrichment through the addition of deep magmatic fluids carrying heavy Zn isotopes. Correlations with Ba and Rb isotopes and Zn isotope signatures in mica and tourmaline support this interpretation. Ascending fluids also transport fluxing components and rare metals, promoting crystal–melt separation and rare-metal enrichment. The work by Luo et al. highlights the role of FAFC in granite evolution, mineralization, and upper continental crust differentiation. https://doi.org/10.2138/am-2025-9889 The periclase-wüstite stability field and the exsolution of coherent nanocrystalline spinel ferrite at 0.1 MPa Caterina Melai, Tiziana Boffa Ballaran, Adrien Neri, Catherine McCammon, Georgios Aprilis, Alena Aslandukovа, Nobuyoshi Miyajima, Daniel Frost This study constrains the ferric iron (Fe3+) content in Fe-bearing periclase under controlled laboratory conditions (0.1 MPa and 1300 °C). Nano-crystalline (5–100 nm) spinel is observed to exsolve depending on Fe content and cooling rate. By combining high-resolution imaging, spectroscopy, and diffraction techniques, Melai et al. were able to understand and resolve the behavior of the spinel ferrite within the ferropericlase matrix and therefore model its stability with f(O2). The experimental results match the exsolutions found in (Mg,Fe)O inclusions in natural diamonds, offering new insights into redox processes and cooling histories in the deep Earth. https://doi.org/10.2138/am-2025-9930 High-resolution Raman spectroscopy of calcium phosphate apatite along the F-OH, F-Cl, and Cl-OH binaries Kyle Ashley, Matthew Steele-MacInnis, Daniel Harlov, John Hughes, Robert Bodnar This study investigates the effects of halogen site substitutions in apatite along each of the binary F-OH, F-Cl, and OH-Cl joins, by quantitative Raman spectroscopy. The results show highly nonlinear variations in Raman peak parameters, including "splitting" of the main apatite Raman peak of Cl-bearing mixed apatites. The results provide a basis for quantitative analysis and provide new insight into the crystal chemistry of halogen substitution in this widespread and useful mineral. https://doi.org/10.2138/am-2025-9938 Disentangling magmatic-hydrothermal evolution of highly fractionated granite through the integration of zircon and monazite U-Th-Pb and Hf/Nd-O isotopes Xing Zhang, Rui Li, Wen-Xiang Zhang, Bin Fu, Guangyan Zhou, Zhaochu Hu, Yuanbao Wu This work by Zhang et al. shows that integrated zircon and monazite U–Th–Pb and Hf/Nd–O isotope analyses reveal the magmatic–hydrothermal evolution of the Wuduoshan pluton, central China. Early magmatic zircon dates granite emplacement at 401.1 ± 4.2 Ma, whereas high-U zircon likely formed from late-stage magmatic fluids. Variable, slightly lower oxygen isotope signatures in late-stage zircon suggest external fluid involvement during crystallization or subsequent alteration. Monazite records a distinct hydrothermal event at 384.4 ± 2.5 Ma, approximately 17 million years after emplacement. Its Nd–O isotope compositions suggest fluids derived from evolved supracrustal materials. These results demonstrate how combined zircon–monazite isotopic analyses can resolve complex granite evolution. https://doi.org/10.2138/am-2025-9941 Effect of Fe content on reduced partition function ratios of Ni isotopes in olivine: A first-principles study Anwen Hou, Jiaxin Liang, Huiquan Tian, Shanqi Liu, Yongbing Li This study employs first-principles calculations to determine the reduced partition function ratios of 60Ni/58Ni (β60-58 factors) for olivine with varying Fe contents. Results show that at fixed Ni concentration, increasing Fe content expands the unit-cell volume and lengthens the average Ni-O bond, thus decreasing β60-58 factor. A strong negative correlation exists between Ni-O bond length and the β60-58 factor. However, Ni content variation negligibly affects β60-58 when Ni/(Ni+Fe+Mg) ≤ 2/32. These findings provide theoretical insights into how Fe content governs Ni isotope fractionation in olivine. https://doi.org/10.2138/am-2025-9946 Origin of tin-specialized granites constrained from fluid-absent metapelite melting experiments Yongchao Liu, Christian Schmidt, Bernd Wunder, Christina Günter, Jiankang Li, Denghong Wang, Zhenyu Chen, Fangyue Wang, Valby Van Schijndel, Oona Appelt, Melanie Sieber Tin-specialized granites typically originate from fluid-absent melting of metapelites. To constrain this, Liu et al. conducted melting experiments on natural pelitic schists at 750–950 °C, 300 and 900 MPa, and f(O2) of ~FMQ-2 to ~FMQ+2.7. The results demonstrate that biotite-dehydration melting is the key process for generating Sn-specialized granites. Critically, Sn partitions into the melt over restite under the investigated conditions. This confirms that favorable protoliths (e.g., pre-enrichment) significantly enhance the potential for Sn mineralization. https://doi.org/10.2138/am-2025-9955 The role of clay minerals in the formation of ferromanganese nodules (FMNs) in Subtropical Monsoonal China Anbei Deng, Lulu Zhao, Hanlie Hong, Qian Fang, Chaowen Wang, Hao Yang, Xincheng Qiu, Fuwen Jia, Bo Fang, Liao Yang, Jiaming Yang, Tingjun Fan, Ying Wang, Zhong-Qiang Chen Exceptionally large iron-manganese nodules (10–50 cm) were discovered in intensely weathered subtropical soils of China. Distinct Fe- and Mn-rich zones exhibit contrasting mineral assemblages and microstructures shaped by redox oscillations. Clay minerals (kaolinite, illite) and gibbsite actively facilitate nodule nucleation and concentric growth processes. Multi-scale analyses reveal Mn-Al interlayering in Mn-rich sub-nodules, indicating complex geochemical segregation. These findings highlight clay minerals as key drivers in FMN genesis and recorders of extreme weathering and redox history. https://doi.org/10.2138/am-2025-9969 Tantalaeschynite-(Ce), a new Ta-dominant member of aeschynite-group from Ta-enriched pegmatite at Huangshan, South China Zeying Zhu, Hong Yu, Zhenyu Chen, Bin Wu, Ru Cheng Wang, Jiankang Li, Denghong Wang In this work, Zhu et al. describe tantaleaschynite-(Ce), ideally Ce(TiTa)O6, a new Ta-dominant member of the aeschynite-group minerals discovered at the border of a pegmatite dike in the Huangshan pegmatite, South China. The spatial distribution of tantalaeschynite-(Ce), combined with the unconventional Ta and Ce enrichment, suggests that the Huangshan pegmatite is a highly evolved NYF pegmatite. The occurrence of tantalaeschynite-(Ce), along with the wide distribution of Ta-metasomatic minerals, underlines the significance of the boundary layer in highly evolved pegmatite systems. https://doi.org/10.2138/am-2025-9971 Nomenclature and classification of the aeschynite-group minerals Zeying Zhu, Hong Yu, Can Rao, Zhenyu Chen, Bin Wu, Ru Cheng Wang, Denghong Wang The nomenclature of aeschynite-group minerals was readdressed to adhere to the most recent IMA-CNMNC rules concerning the endmember formula, particularly in the case of valency-imposed double site-occupancy. Applying all general criteria to all minerals belonging to aeschynite group, Zhu and coauthors in this work proposed in total only seven valid end-members of the aeschynite group, which are: rynersonite (CaTa2O6), vigezzite (CaNb2O6), aeschynite-(Ce) [Ce(TiNb)O6], aeschynite-(Nd) [Nd(TiNb)O6], aeschynite-(Y) [Y(TiNb)O6], tantalaeschynite-(Y) [Y(TiTa)O6]. and tantalaeschynite-(Ce) [Ce(TiTa)O6]. https://doi.org/10.2138/am-2025-9978 In situ U-Pb chronology and chemistry of zirconolite in the andesitic meteorite Erg Chech 002 Jun Sakuma, Hisashi Asanuma, Akira Yamaguchi, Naoto Takahata, Tsuyoshi Iizuka Sakuma et al. present the in situ occurrence, chemistry, and U-Pb chronology of zirconolite in the andesitic meteorite Erg Chech 002. The Pb isotopic data define an age of 4557.9 ± 4.3 Ma, which is the oldest age reported for this mineral. Based on the mineralogy and REE-(Th+U)-(Nb+Ta) systematics, the authors argue that the zirconolite age presents the timing of shock metamorphism. The results demonstrate the potential of zirconolite to refine early Solar System chronology. https://doi.org/10.2138/am-2025-9995