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 is a feature open to anyone who registers on the site. Thank you for reading American Mineralogist. Sincerely, Hongwu Xu Paul Tomascak Editors, American Mineralogist American Mineralogist Volume 110; Number 4; 04-01-2025 Quantifying the potential for mineral carbonation of processed kimberlite with the Rietveld-PONKCS method Baolin Wang, Nina Zeyen, Sasha Wilson, Rebecca Funk, and Connor C. Turvey This paper describes conditions under which X-ray diffraction (XRD) data and PONKCS models can and cannot be used to accurately quantify mineral phases and carbon sequestration potential in ultramafic landscapes. Wang et al. created lizardite and montmorillonite PONKCS models using XRD patterns collected with three different X-ray diffractometers. Five synthetic samples of processed kimberlite with known compositions were used to test the results of instrument-specific PONKCS models and data collected from each instrument. The results show that even small differences in instrument parameters can lead to inconsistent and inaccurate quantitative phase analysis (QPA) results using PONKCS (i.e., 9.8-32.5 wt% total bias). However, the results provide a total bias ranging from 4.2-14.1 wt% using correctly calibrated, instrument-specific PONKCS models. This work represents the first direct comparison of PONKCS models calibrated to different X-ray diffractometers, providing a useful test of the accuracy and portability of this method for quantifying crystallographically disordered minerals. https://doi.org/10.2138/am-2023-9103 Magnetic collapse and low conductivity of Fe3N in the deep interiors of Earth-like planets Yukai Zhuang, Jin Liu, Chaojia Lv, Liangxu Xu, Wenli Bi, Qingyang Hu, Dongzhou Zhang, Gaston Garbarino, Shengcai Zhu, and Youjun Zhang Nitrogen is an abundant element in the solar system and recent studies have indicated that its content in the deep Earth may be higher than previously believed. This is due to its affinity for iron and its association with carbon and nickel. Understanding the Fe-N system under high pressure has, therefore, become a topic of great interest, especially for Fe3N. Recent natural observations demonstrated that Fe3N is a kind of inclusion in lower-mantle diamond from Rio Soriso, Brazil. Zhuang et al. investigated the physical and chemical properties of Fe3N, including its magnetic, structural, electrical, and thermal properties, for the first time at pressures up to 62 GPa and temperatures up to 2100 K. The results show that Fe3N is stable along the geotherm, and its distinct thermal properties would impact the thermal state and dynamics of the deep interior of Earth and other terrestrial planets. https://doi.org/10.2138/am-2023-9251 Two modes of terrestrial phosphide formation Evgeny Galuskin, Irina Galuskina, Yevgeny Vapnik, Joachim Kusz, Beata Marciniak-Maliszewska, and Grzegorz Zieliński Galuskin et al. conducted a study of terrestrial phosphides from the large tridymite-anorthite-diopside paralava body of the Hatrurim Complex, Jordan, where several new phosphides and phosphates were previously discovered. Phosphides enrich the contact facies of the paralava and occur in small nodules in the central part of the paralava body. In one of these nodules, nickelphosphide was discovered for the first time on Earth. The authors discuss two formation modes of phosphides in terrestrial rocks. https://doi.org/10.2138/am-2024-9315 Ferric vs. ferrous arsenate amorphous precursors: Properties and controls on scorodite mineralization Pei Chang, Xiangyu Zhu, Hongming Cai, Jianchao Zhang, Siliang Li, Xiancai Lu, Rucheng Wang, and H. Henry Teng Chang et al. investigate the chemical and structural properties of amorphous ferrous arsenate (AFeII) formed in Fe(II)-As(V) systems and compare these properties and related scorodite mineralization processes to those of amorphous ferric arsenate (AFeIII). Amorphous iron-arsenate precipitates are significant As sinks in natural and industrial settings, often serving as precursors to the crystallization of ferric arsenate minerals. The authors determined the chemical formulae and local structure of synthesized AFeIII and AFeII using a range of techniques, including XRD, FTIR, synchrotron-based XAFS, SEM, and TEM. The results revealed that the presence of Fe(II) in AFeII increases the Fe-O bond distance and hinders its crystallization to scorodite under both atmospheric and aqueous conditions. These findings shed light on the role of AFeII during the amorphous-scorodite phase transition, ultimately enhancing our understanding of the iron arsenate system. https://doi.org/10.2138/am-2024-9326 Jianmuite, ZrTi4+Ti53+Al3O16, a new mineral from the Allende meteorite and from chromitite near Kangjinla, Tibet, China Roberto Borriello, Fahui Xiong, Chi Ma, Sofia Lorenzon, Enrico Mugnaioli, Jingsui Yang, Xiangzhen Xu, and Edward S. Grew Borriello et al. describe the chemical composition and crystal structure of a new mineral jianmuite, ZrTi4+Ti3+5Al3O16. The mineral was found as (1) an inclusion in a corundum grain from the Cr-11 orebody near Kangjinla, Tibet, China (holotype and first co-type) and (2) several grains with corundum, mullite and other minerals in the matrix of the CV3 carbonaceous chondrite Allende (second co-type). The authors chose Jianmu, the sky ladder tree of Chinese myth, as the name for the new mineral, jianmuite. https://doi.org/10.2138/am-2024-9362 Titanite and allanite as a record of multistage co-mobility of Ti-REE-Nb-As during metamorphism in the Central Alps Joël Brugger, Stéphane Cuchet, Ate van der Burgt, Mischa Crumbach, Barbara Etschmann, Yanlu Xing, Rahul Ram, Paul Michaut, Oliver Nebel, Massimo Raveggi, Roland Maas, Mark A. Pearce, and Daryl L. Howard The Binntal Valley, Switzerland, features a remarkable mineralogical diversity, making it one of the world's few mineralogical rainforests. Brugger et al. describe a new type of mineralization that results from the local remobilization of small amounts of titanium, niobium, rare earth elements, and arsenic during Alpine metamorphism. The authors show that most mineralogical diversity arises from the channeled flow of small amounts of CO2-bearing fluids during the exhumation of these rocks. https://doi.org/10.2138/am-2024-9378 Unusual sulfide-rich magmatic apatite crystals from >2.7 Ga Abitibi Greenstone Belt, Canada Xuyang Meng, David R. Mole, Adam C. Simon, Jinwen Mao, Daniel J. Kontak, Pedro J. Jugo, and Jackie M. Kleinsasser Meng et al. employed synchrotron-based X-ray absorption near edge structure (XANES) analysis to reveal the rare presence of sulfide-rich magmatic apatite crystals formed in the Abitibi Greenstone Belt 2.7 billion years ago. The XANES results indicate a weak S emission from Earth's interior to the surface, providing a potential explanation for the rarity of porphyry Cu deposits on early Earth despite the prevalence of sodic TTG rocks. https://doi.org/10.2138/am-2024-9387 Macro- to nanoscale investigation unlocks gold and silver enrichment by lead-bismuth metallic melts in the Switchback epithermal deposit, southern Mexico Néstor Cano, José María González-Jiménez, Antoni Camprubí, Joaquín A. Proenza, and Eduardo González-Partida This study presents macro- to nanoscale observations on Pb-Bi sulfides and sulfosalts associated with Au-Ag in a low-temperature hydrothermal ore deposit of the epithermal type. These minerals show textural evidence indicative of crystallization from a metallic melt precursor that was being transported by an aqueous fluid below 400 °C. Such a melt, enriched in precious metals, likely contributed to focusing Au-Ag ores. Upon cooling, the melt crystallized Pb-Bi minerals that underwent replacement processes and gave rise to "false" exsolution-suggestive textures. https://doi.org/10.2138/am-2024-9388 Synthesis and characterization of Fe-poor olivine with applications to the surface of Mercury Brendan A. Anzures, Kathleen E. Vander Kaaden, Francis M. McCubbin, Richard L. Rowland II, Gordon M. Moore, Kelsey Prissel, Richard V. Morris, Rachel L. Klima, Karen R. Stockstill-Cahill, and David G. Agresti Anzures et al. characterized synthetic olivine with minor amounts of Fe (i.e., Fo99.62-Fo99.99) using a variety of spectroscopic techniques. The results show that the characteristic 1 µm absorption band is detectable in reflectance spectra of olivine at a concentration as low as 0.03 wt% FeO as well as 0.01 wt% in continuum removed data. Additionally, MESSENGER's lack of a 1 µm absorption, taking into account MDIS's limited spectral resolution and MASCS's high signal-to-noise, suggests that there is less than 0.38 wt%, and likely less than 0.01 wt%, FeO on the surface of Mercury. Because the 1 µm band is not observed in surface spectra, these results indicate that the Fe observed on the surface of Mercury is not bound in an olivine structure but rather in Fe metal. https://doi.org/10.2138/am-2024-9400 Multi-analytical characterization of an unusual epidote-supergroup mineral from Malmkärra, Sweden: Toward the new (OH)-analog of dollaseite-(Ce) Alice Taddei, Paola Bonazzi, Hans-Jürgen Förster, Patrick Casey, Dan Holtstam, Andreas Karlsson, and Luca Bindi A study of a skarn sample from the Malmkärra iron mines, Norberg, Västmanland revealed the occurrence of a peculiar epidote-supergroup mineral. Taddei et al. examined this mineral using electron microprobe, single-crystal X-ray diffraction, Mössbauer and Fourier-transform infrared spectroscopy techniques. Structure refinements combined with electron-microprobe data indicate that: A1 = Ca0.96REE3+0.03Mn0.01; A2 = REE3+0.99Ca0.01; M1 = Mg0.40Al0.32Fe3+0.26Fe2+0.02; M2 = Al0.98Fe3+0.02; M3 = Mg0.72Fe2+0.17Fe3+0.11; T1,2,3 = Si2.93Al0.07, accounting for a total positive charge of 24.64. The likely incorporation of additional hydrogen in epidote-supergroup minerals exerts control on the mineral structure and properties and has various geological implications. Additionally, the importance of additional water in epidote-supergroup minerals is multifaceted, influencing their structure, properties, and role in various geological processes, such as metamorphism and hydrothermal alteration. https://doi.org/10.2138/am-2024-9438 Late-stage microstructures in Chang’E-5 basalt and implications for the evolution of lunar ferrobasalt Ziliang Jin, Tong Hou, Meng-Hua Zhu, Yishen Zhang, and Olivier Namur Jin et al. investigated silicate liquid immiscibility (SLI) microstructures in the Chang’E-5 (CE-5) lunar ferrobasalt sample, the youngest recovered mare basalt (ca. ~2.0 Ga). Using high-resolution imaging techniques and chemical analysis, they examined a subophitic fragment, revealing stable and metastable SLI microstructures indicative of multi-stage SLI events. Metastable SLI has both chemical and physical impacts on the late-stage evolution of lunar ferrobasalt. https://doi.org/10.2138/am-2024-9448 RamanCrystalHunter: A new program and database for processing, analysis, and identification of Raman spectra Fabrizio Nestola, Qiwei Zhang, Maxwell C. Day, Sofia Lorenzon, Martha G. Pamato, Ivano Rocchetti, Claudio Bendazzoli, Davide Novella, Claudio Mazzoli, Raffaele Sassi, D. Graham Pearson, Evan M. Smith, Michael Scott, Anna Barbaro, Frank E. Brenker, Lisa Santello, Simone Molinari, Kai Qu, Yanjuan Wang, Radek Škoda, Matteo Alvaro, Mattia Gilio, Mara Murri, and Anatoly V. Kasatkin RamanCrystalHunter is a new software program for processing, analyzing, and identifying the Raman spectra of minerals and other geologic materials. Users can perform baseline corrections, spectrum addition and subtraction, and fitting operations. RCH includes a new database (RCHDB) of high-quality mineral spectra that allows efficient and accurate mineral identification. https://doi.org/10.2138/am-2024-9457 Cabrerite, NiMg2(AsO4)2·8H2O, a new old mineral: The ordered intermediate between annabergite and hörnesite Anthony R. Kampf, Paul M. Adams, and Chi Ma Although cabrerite was first described in 1863, it has long been regarded as merely an Mg-rich variety of annabergite in the solid-solution series between annabergite and hörnesite. Previous studies of Mg-rich annabergite have shown the ordering of Ni and Mg in two distinct octahedrally coordinated cation sites, but in all past structure studies, both sites have been dominated by Ni. In the investigation of more Mg-rich crystals from the Nickel mine in Nevada, the authors have found Ni to be dominant in one site and Mg in the other, thereby qualifying the mineral as a distinct species—the ordered intermediate between annabergite and hörnesite. Based on tentative compositional boundaries in the annabergite-cabrerite-hörnesite series, the original material described as cabrerite from Sierra Cabrera, Spain, is likely to qualify as the same species, hence justifying the reuse of the name cabrerite. The newly described mineral is the third member of the vivianite group to be described based on the ordering of cations in distinct octahedrally coordinated cation sites. https://doi.org/10.2138/am-2024-9498 Discovery of an Earthborn quasicrystal approximant Luca Bindi, Louis J. Cabri, Marek Mihalkovič, Frantisek Laufek, and Sergey V. Krivovichev The discovery of proxitwelvefoldite, a new mineral and the first known terrestrial approximant of a dodecagonal quasicrystal, represents a significant advancement in understanding quasicrystal formation and its potential occurrence in terrestrial environments. Quasicrystals, previously only identified in extraterrestrial materials and metallic alloys, were considered highly unlikely to form naturally on Earth due to the reducing conditions required for the presence of metallic aluminum. However, the present finding challenges that assumption and expands the known geochemical contexts where quasicrystalline approximants might arise, and it invites a deeper exploration into the diversity of Earth's mineral systems, offering exciting new possibilities for discovering novel materials with unique properties. https://doi.org/10.2138/am-2024-9679