^1,2,3Timothy K. Johnsen,^1,2,4Virginia C. Gulick
American Mineralogist 110, 685-698 Link to Article [https://doi.org/10.2138/am-2023-9072]
¹Planetary Systems Branch, NASA Ames Research Center, MS 239-20, Moffett Field, California 94035, U.S.A.
²SETI Institute, 339 Bernardo Avenue, Suite 200, Mountain View, California 94043, U.S.A.
³Computational Science Research Center, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, U.S.A.
⁴Department of Planetary Sciences, Lunar and Planetary Lab, University of Arizona, 1629 E. University Boulevard, Tucson, Arizona 85721, U.S.A.
Copyright The Mineralogical Society of America

Planetary surface missions have greatly benefitted from intelligent systems capable of semi-autonomous navigation and surveying. However, instruments onboard these missions are not similarly equipped with automated science analysis classifiers onboard rovers, which can further improve scientific yield and autonomy. Here, we present both single- and multi-mineral autonomous classifiers integrated using the results from a co-registered dual-band Raman spectrometer. This instrument consecutively irradiates the same spot size on the same sample using two excitation lasers of different wavelengths (532 and 785 nm). We identify the presence of mineral groups: pyroxene, olivine, potassium feldspar, quartz, mica, gypsum, and plagioclase, in 191 rocks. These minerals are among the major rock-forming mineral groups, so their presence or absence within a sample is key for understanding rock composition and the environment in which it formed. We present machine learning methods used to train classifiers and leverage the multiple modalities of the dual-band Raman spectrometer. When testing on a novel sample set for single-mineral classification, we show accuracy scores up to 100% (varying by mineral), with a total classification rate (all minerals) of 91%. When testing on a novel set of samples for multi-mineral classification, we show accuracy scores up to 96%, with a total classification rate of 73%. We end with several hypothesis tests demonstrating that dual-band Raman spectroscopy is more robust and improves the scientific yield for mineral classification over single-band spectroscopy, especially when combined with our multimodal neural network.

^1,2,3Xiaorong Qin et al. (>10)
American Mineralogist 110, 791-807 Link to Article [https://doi.org/10.2138/am-2024-9374]
¹State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry/ Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
²CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
³University of Chinese Academy of Sciences, Beijing 100049, China
Copyright: The Mineralogical Society of America

Al-hematite occurs in a wide range of terrestrial soils, but the impact of hydrologic factors on the formation and preservation of Al-hematite remains uncertain. Experimental studies indicate that the ratio of the intensity (I) of the (110) reflection to the intensity of the (104) reflection [(I(110)/I(104)] increases with increasing Al content in a series of synthetic Al-hematite analyzed by X-ray diffraction (XRD), whereas the ratio of the full-width at half maximum of the (110) reflection to the full-width at half maximum of the (104) reflection [W(110)/W(104)] decreases. Quantitative constraints were applied to determine the various levels of Al-substituted hematite in a basaltic laterite (a 48-m-long drill hole) from Hainan Island in South China. The spatial correlation between the distribution of hematite with varying Al content and the location of the groundwater table in the basaltic laterite indicates that hydrologic conditions play a crucial role in regulating the formation and preservation of Al-hematite. The weathering of basalt in a stable water-saturated environment with a relatively slower flow rate promotes the formation of Al-poor hematite. Conversely, the formation of Al-rich hematite was favored by a relatively high flow rate and alternating wet and dry conditions above the groundwater table. Additionally, capillary water in the surficial soil facilitates the expulsion of Al during the recrystallization of Al-rich hematite, resulting in the formation of Al-poor hematite in the surficial soil. Observations from landed instruments and ground-based telescopes have led to the longstanding suspicion that Al-hematite exists on the surface of Mars. The potential presence of Al-hematite in certain martian outcrops may suggest the existence of transient liquid water with slightly higher flow rates, such as episodic floods, emphasizing the dynamic hydrologic conditions on Mars. Moreover, this study suggests that visible and near-infrared (VNIR) spectroscopy can be employed to identify and characterize Al-rich hematite. This approach could be employed to assess the potential presence of Al-rich hematite on Mars, aiding in the study of the planet’s hydrologic environment.

¹J.Gattacceca et al.(>10)
Meteoritics & Planetary Science (in Press) (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14359]
¹CNRS, Aix Marseille Univ, IRD, INRAE, CEREGE, Aix-en-Provence, France
Published by arrangement with John Wiley & Sons

CI1 chondrites are rare meteorites with high scientific value. In fact, they are the most chemically primitive meteorites and show evidence of intense parent-body aqueous alteration. They also share strong similarities with samples from Ryugu and Bennu asteroids returned by the JAXA Hayabusa2 and NASA’s OSIRIS-REx missions. In this work, we present a detailed study of the Oued Chebeika 002 meteorite, a ~420 g CI1 chondrite found in Morocco in 2024. We describe its petrography, texture, and mineralogy, with a focus on clay mineralogy. We provide the bulk and mineral chemical composition, as well as the bulk oxygen, iron, and chromium isotopic compositions. Spectroscopic properties were studied by means of infrared and Raman spectroscopies. We also measured the density, grain density and magnetic properties. Our results confirm that Oued Chebeika 002 is a CI1 chondrite, with close similarities to the other five know CI1 chondrites, and samples from Ryugu and Bennu asteroids. Several lines of evidence indicate that Oued Chebeika 002 has suffered no significant terrestrial alteration. It is more pristine in that regard than Alais, Orgueil and Ivuna CI1 chondrites, and more similar to samples from asteroids Ryugu and Bennu. Subtle differences exist between Oued Chebeika 002 and other CI1 chondrites that cannot be accounted for by terrestrial alteration of the latter. For instance, olivine and calcite were not observed. It is also noteworthy that the magnetic mineral assemblage of Oued Chebeika 002 is significantly different from that of Alais, Ivuna and Orgueil, but undiscernible from that of Ryugu samples. Chromium and iron isotopic composition of Oued Chebeika 002 confirms that CI1 chondrites, like Ryugu samples, are distinct from meteorites belonging to the non-carbonaceous and carbonaceous isotopic groups and may have originated from the same region where ice giant planets and Oort Cloud comets were formed.

¹M. Broussard,¹M. Neuman,¹B. L. Jolliff,¹P. Koefoed,¹R. L. Korotev,²R. V. Morris,³K. C. Welten,¹K. Wang
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2024JE008371]
¹Department of Earth, Environmental, and Planetary Sciences and the McDonnell Center for the Space Sciences,
Washington University in St. Louis, St. Louis, MO, USA
²ARES NASA Johnson Space Center, Houston, TX, USA
³Space Sciences Laboratory, University of California, Berkeley, CA, USA
Published by arrangement with John Wiley & Sons

Space weathering alters the surface materials of airless planetary bodies; however, the effects on moderately volatile elements in the lunar regolith are not well constrained. For the first time, we provide depth profiles for stable K and Fe isotopes in a continuous lunar regolith core, Apollo 17 double drive tube 73001/2. The top of the core is enriched in heavy K isotopes (δ41K = 3.48 ± 0.05‰) with a significant trend toward lighter K isotopes to a depth of 7 cm; while the lower 44 cm has only slight variation with an average δ41K value of 0.15 ± 0.05‰. Iron, which is more refractory, shows only minor variation; the δ56Fe value at the top of the core is 0.16 ± 0.02‰ while the average bottom 44 cm is 0.11 ± 0.03‰. The isotopic fractionation in the top 7 cm of the core, especially the K isotopes, correlates with soil maturity as measured by ferromagnetic resonance. Kinetic fractionation from volatilization by micrometeoroid impacts is modeled in the double drive tube 73001/2 using Rayleigh fractionation and can explain the observed K and Fe isotopic fractionation. Effects from cosmogenic 41K (from decay of 41Ca) were calculated and found to be negligible in 73001/2. In future sample return missions, researchers can use heavy K isotope signatures as tracers of space weathering effects.

^1,2Antonin Wargnier et al. (>10)
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116611]
¹LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université de Paris-Cité, CY Cergy Paris Université, CNRS, 5 place Jules Janssen, Meudon, 92195, France
²LATMOS, CNRS, Université Versailles St-Quentin, Université Paris-Saclay, Sorbonne Université, 11 Bvd d’Alembert, Guyancourt, F-78280, France
Copyright Elsevier

^1,2X. Zhu,¹Y. Ye,^2,3R. Caracas
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2024JE008839]
¹State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Wuhan, China
²Institut de Physique du Globe de Paris, CNRS, Université Paris Cité, Paris, France
³The Research Center of the University of Bucharest, Bucharest, Romania
Published by arrangement with John Wiley & Sons

The formation and evolution of rocky planets such as the Earth are marked by the heavy bombardments that dominated the first parts of the accretions. The outcomes of the large and giant impacts depend on the critical points and liquid-vapor equilibria of the constituent materials. Several determinations of the positions of the critical points have been conducted in the last few years, but they have mainly focused on systems devoid of volatiles. Here, we study, for the first time, a volatile-rich ubiquitous model mineral, phlogopite. For this, we employ ab initio molecular dynamics simulations. Its critical point is constrained in the 0.40–0.68 g/cm3 density range and 5,000–5,500 K temperature range. This shows that adding volatiles decreases the critical temperature of silicates while having a smaller effect on the critical density. The vapor phase that forms under cooling from the supercritical state is dominated by hydrogen, present in the form of H2O, H, OH, with oxygen and various F-bearing phases coming next. Our simulations show that up to 93% of the total hydrogen is retained in the silicate melt. Our results suggest that early magma oceans must have been hydrated. In particular for the Moon’s history, even if catastrophic dehydrogenation occurred during the cooling of the lunar magma ocean, the amount of water incorporated during its formation could have been sufficient to explain the amounts of water found today in the last lunar samples.

¹W. H. Farrand et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2024JE008645]
¹Space Science Institute, Boulder, CO, USA
Published by arrangement with John Wiley & Sons

The Mars Science Laboratory rover, Curiosity, has been examining strata from a period of Martian history where extensive clay mineral formation transitioned to sulfate mineral formation. This mineralogic change corresponds to a change from a wetter to a more arid climate. Among the tools used by Curiosity to study the rocks that recorded this transition is the multispectral capability of its Mast Camera (Mastcam). The Mastcam filter wheel, in combination with its Bayer Pattern filter focal plane array has provided multispectral scenes recorded in 12 spectral bands over the 445–1,013 nm spectral range. Here, Mastcam multispectral results from the rover’s exploration of predominantly sulfate-bearing strata that bracket a distinct dark-toned resistant stratigraphic marker unit, now referred to as the Amapari Marker Band (AMB), are presented in association with supporting information from some of Curiosity’s other instruments. Using an agglomerative hierarchical clustering approach, six spectral classes were derived. These classes included three stratigraphic classes plus a class indicating more intense diagenetic alteration and classes of dark-toned float rocks and a set of Fe-Ni meteorites. These spectral classes were compared to the spectra of analogous terrestrial materials. Among the observations, a distinct tonal and color unit was observed directly below the Amapari Marker Band. Several lines of evidence suggest this narrow interval is an alteration horizon. The alteration could have resulted from diagenesis, exposure as a weathering surface, or from introduction of water associated with the deposition of the lower AMB.

¹T.A. Williams, ¹S.W. Parman, ¹A.E. Saal, ²A.J. Akey, ²J.A. Gardener, ³R.C. Ogliore
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116607]
¹Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, United States of America
²Center for Nanoscale Systems, Harvard University, Cambridge, MA, United States of America
³Department of Physics, Washington University in St. Louis, St. Louis, MO, United States of America
Copyright Elsevier

Lunar pyroclastic glass beads preserve a record of physical and chemical conditions within volcanic gas clouds in the form of nanoscale minerals vapour-deposited onto their surfaces. However, the scale of these mineral deposits – less than 100 nm – has presented challenges for detailed analysis. Using SEM, TEM, APT, and NanoSIMS, we analysed pristine glass beads from Apollo drive tube 74,001 and found a sequence of sulfide deposition that directly evidences lunar gas cloud evolution. The deposits are predominantly micromound structures of nanopolycrystalline sphalerite ((Zn,Fe)S), with iron enrichment at the bead-micromound interface. Thermochemical modelling indicates that hydrogen and sulfur were major elements within the volcanic plume and ties the iron gradient to decreasing gas pressure during deposition. This pressure drop may also be consistent with our observed trend of potential
depletion. Finally, Apollo 1,774,220 orange beads, deposited higher in the Shorty Crater sequence, appear to lack abundant ZnS nanocrystals (Liu and Ma, 2024a), suggesting a change in vapour deposition between black- and orange-glass bead deposition. Together, our results suggest a change in eruption style over the course of a pyroclastic volcanic eruption in the Taurus-Littrow Valley.

¹Piers Koefoed, ¹Kun Wang (王昆)
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.04.012]
¹Department of Earth, Environmental, and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA
Copyright Elsevier

Understanding chondrule formation processes has been a major focus of the cosmochemistry community for many decades. In order to help further this understanding, here we apply high-precision K isotope analyses to chondrule fractions from the four Antarctic unequilibrated ordinary chondrites of QUE 97008 (L3.05), MET 00452 (L(LL)3.05), GRO 95658 (LL3.3), and GRO 95539 (LL3.2). The K isotope ratios of the chondrules fractions from all four of these samples lie within the range of −2.20 ‰ to 0.14 ‰ δ41K, with QUE 97008, MET 00452, GRO 95658, and GRO 95539 showing chondrule fraction δ41K ranges of −1.54 to 0.14 ‰, −0.76 to −0.28 ‰, −2.20 to −1.23 ‰, and −1.30 to −0.84 ‰, respectively. Overall, no strong correlations between K isotope ratio and K concentration are observed among the chondrule fractions for any of the four chondrites. Additionally, unlike what was seen previously for the LL4 Hamlet, no correlation between chondrule mass and K isotope ratio was observed. In conjunction with previous studies, the data here suggest that a combination of secondary parent body processes and nebular processes involved in chondrule formation are the dominant controls on the K isotope systematics of the chondrules from unequilibrated ordinary chondrites. The effects of secondary parent body processing vary significantly from chondrule to chondrule, however, the dominant effect is the migration of K from the K rich matrix to the K poor chondrules. As such, parent body alteration partially overprinted and disturbed the initial chondrule K compositions to various degrees. Nevertheless, even with the effects of parent body processing, the key observation that the vast majority of the chondrule fractions show δ41K values lighter than, or equal to, their respective matrix and bulk compositions is best explained by these chondrules experiencing incomplete condensation in the solar nebula. This aligns with K isotope observations made for the carbonaceous chondrites where the matrix-dominated CI chondrites are enriched in heavier K isotopes and the chondrule-rich carbonaceous chondrites are enriched in lighter K isotopes. The K isotopes of individual chondrules in this study suggest that chondrules from ordinary chondrites were also formed via incomplete condensation from a supersaturated medium, agreeing with the previous conclusion drawn for carbonaceous chondrules. This means both CC and OC chondrules likely experienced incomplete condensation, making this chondrule formation process ubiquitous and widespread throughout both the inner and outer regions of early solar nebula.

^1,2,3Liam D. Peterson,³Megan E. Newcombe,⁴Conel M.O’D. Alexander,⁴Jianhua Wang,^1,2,5Sune G. Nielsen
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.04.009]
¹Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02540, United States
²NIRVANA Labs, Woods Hole Oceanographic Institution, Woods Hole, MA 02540, United States
³Department of Geology, University of Maryland, College Park, MD 20740, United States
⁴Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, United States
⁵CRPG, CNRS, Université de Lorraine, 15 rue Notre Dame des Pauvres, 54501 Vandoeuvre lès Nancy, France
Copyright Elsevier

Erg Cech 002 (EC 002) is an andesitic achondrite, the earliest formed achondrite identified to date, and is a rare sample of primary melts that formed crusts on the first generation(s) of planetesimals. Given that EC 002 represents a primary or primitive melt and that H and F are incompatible during silicate partial melting, EC 002 may be a H- and F-rich material relative to previously studied achondrites. We measured the H2O (total H quantified as H2O) and F contents of low-Ca pyroxene xenocrysts (∼4– 12 µg/g H2O; <0.5 µg/g F), groundmass augite (∼5 – 10 µg/g H2O; <2.2 µg/g F), albitic feldspar (∼2– 5 µg/g H2O; <0.5 µg/g F), and a silica-rich phase (∼28– 30 µg/g H2O; ∼0.7– 2.5 µg/g F) in EC 002 by Nanoscale Secondary Ion Mass Spectrometry. We use a single-stage equilibrium batch melting model to provide a first-order reconstruction of the EC 002 parent body H2O (∼7– 200 µg/g H2O) and F (∼0.44– 2.4 µg/g F) contents, which are depleted relative to chondrites and the bulk Earth. This requires the first generation(s) of planetesimals to have either accreted from volatile-poor materials or undergone extensive volatile loss, supporting the idea that Earth acquired its H2O budget from thermally primitive materials.