^1,2Varsha M. Nair, ¹Amit Basu Sarbadhikari, ³G.N.S. Sree Bhuvan, ⁴T. Vijaya Kumar, ^5,6Nilanjana Sorcar, ⁶Sneha Mukherjee, ⁴E.V.S.S.K. Babu, ¹Jyotiranjan S. Ray
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.09.043]
¹Physical Research Laboratory, Ahmedabad 380009, India
²Indian Institute of Technology Gandhinagar, Gujarat 382355, India
³Department of Earth Sciences, Pondicherry University, Puducherry 605014, India
⁴CSIR-National Geophysical Research Institute, Hyderabad 500007 India
⁵National Centre for Earth Science Studies, Akkulam, Thiruvananthapuram 695011, India
⁶Korea Polar Research Institute, Incheon 21990, the Republic of Korea
Copyright Elsevier

Martian meteorite Northwest Africa (NWA) 1950 is a poikilitic shergottite whose whole-rock chemical and isotopic composition indicates its origin from an intermediate mantle source. In this study, we report the results of a detailed petrographic, in-situ trace element, and whole-rock Sr-Nd isotopic investigation carried out on NWA 1950 to understand the cause of the apparent absence of the depleted poikilitic shergottites among the Martian meteorites. The sample exhibits distinct poikilitic and non-poikilitic textural domains. The large pyroxene oikocrysts (up to ∼2 mm) enclose early-formed olivine and chromite inclusions (chadacrysts) in the poikilitic domain. The non-poikilitic domain comprises olivine, pyroxene, maskelynite, merrillite, and other late-stage minerals. Pyroxenes exhibit a highly LREE-depleted pattern, and maskelynite shows no evidence of LREE enrichment. Merrillite is characterized by low REE abundance and a slight negative Eu anomaly, resembling those of depleted olivine-phyric shergottites like Tissint. Olivine grains contain abundant melt inclusions in the poikilitic and non-poikilitic domains. Oxygen fugacity values in the poikilitic and non-poikilitic domains are QFM-2.8 and QFM-2.5, respectively. The measured 87Sr/86Sr and 143Nd/144Nd ratios for NWA 1950 whole-rock are 0.710432 ± 0.000027 and 0.513201 ± 0.000011, respectively. The REE pattern of melt inclusions is depleted, resembling the depleted shergottites, while the whole-rock REE and Sr-Nd isotopic compositions are of intermediate class. This characteristic of the NWA 1950 melt inclusions enables us to establish a genetic linkage between the intermediate and depleted shergottites and to find out the missing link for the depleted poikilitic shergottites.
The parent magma of NWA 1950 is more magnesian and less aluminous than that of the enriched poikilitic shergottites in the same manner that depleted olivine-phyric shergottites have more Mg and less Al than their enriched counterparts. Additionally, the modal proportion of pyroxene to plagioclase and REE abundance in merrillite of NWA 1950 closely matches the depleted olivine-phyric shergottites. The observed enrichment in trace elements and the Sr-Nd isotopic compositions cannot be explained by a depleted mantle source, as inferred from the REE patterns of the constituent minerals in NWA 1950. We propose such enrichment to have originated due to the heterogeneity in the shergottite mantle, aided by the entrapped melt pockets within the upper mantle. A mixture of 0.3–1.0 % trapped liquid in the Martian upper mantle with the parent melt can produce the high REE abundance and Sr-Nd isotopic composition of NWA 1950. Longer residence time in the magma chamber and slower cooling rate of the poikilitic shergottites than the extrusive shergottites could have aided the enrichment in the source region. Additionally, this study suggests that care must be taken in classifying the chemical and isotopic characteristics of the poikilitic shergottites in future studies.

¹Molly C. McCanta,^2,3M. Darby Dyar,^4,5Stephen R. Sutton,⁶Sarah E. Roberts,^7,8Cai R. Ytsma
American Mineralogist 110, 1597-1613 Link to Article [https://doi.org/10.2138/am-2024-9602]
¹Department of Earth, Environment, and Planetary Sciences, University of Tennessee, 1621 Cumberland Avenue, Knoxville, Tennessee 37996, U.S.A.
²Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, Arizona 85719, U.S.A.
³Department of Astronomy, Mount Holyoke College, 50 College Street, South Hadley, Massachusetts 01075, U.S.A.
⁴Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, U.S.A.
⁵Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois 60637, U.S.A.
⁶Corning Glass, Corning, New York 14830, U.S.A.
⁷Cai Consulting, Glasgow, Scotland, U.K.
⁸Institute of Health Informatics, University College London, Gower Street, London WC1E 6BT, U.K.
Copyright: The Mineralogical Society of America

Iron redox works well for constraining oxygen fugacity (⁠⁠) in terrestrial igneous materials due to the relatively high  of the Earth’s atmosphere, crust, and upper mantle ⁠, where there are large changes in Fe²⁺/Fe³⁺ with relatively small changes in ⁠. At  values <QFM, Fe redox becomes less sensitive, and analytical uncertainties may make it difficult to determine  differences between samples. The valence change between Cr²⁺ and Cr³⁺ occurs at lower  values than for iron, potentially making it a more sensitive oxybarometer for materials equilibrated under reducing conditions. The current approach to measuring  from X-ray absorption (XAS) measurements derives Cr valence first from the 1s → 4s transition and then uses that redox couple to estimate  as a function of temperature and composition. Here, that method is compared to an alternate approach of predicting  directly from the spectra of experimentally homogenized glasses of geological relevance without an intermediate step of attempting to discern Cr²⁺/Cr³⁺. In this study, partial least-squares (PLS) multivariate (MVA) regression models were trained on the whole XAS energy spectral range, and accuracy was quantified using root mean square error (RMSE). MVA results showed significantly higher accuracy (RMSE-C of ±0.75 log units) for predicting  ΔIW relative to known experimental conditions relative to the two-step method, which yielded RMSE-C of ±2.75 to ±7.65 log units for our data set vs. those of Berry and O’Neill (2004) and Berry et al. (2006), respectively. The MVA results calibrate a new Cr oxybarometer for use in low- glasses with a cross-validated (RMSE-CV) accuracy of ±0.84 log units  relative to a standard oxygen buffer. Finally, the new Cr oxybarometer was applied to lunar glasses, both volcanic and impact metamorphosed, to assess the range in oxidation conditions the materials experienced during formation. Lunar volcanic glasses cluster ∼IW±1, close to that of previous studies while agglutinates and lunar impact melts record a wide range of  values using Cr oxybarometry.

¹Dwijesh Ray,¹Aditya Das,¹Subham Sarkar,²Satadru Bhattacharya,³Chandrani Nayak
American Mineralogist 110, 1516-1526 Link to Article [https://doi.org/10.2138/am-2024-9360]
¹Physical Research Laboratory, Ahmedabad 380 009, India
²Space Applications Centre (ISRO), Ahmedabad 380 015, India
³Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
Copyright: The Mineralogical Society of America

We report mineralogy, chemical composition, visible near-infrared (VNIR) spectroscopy, and X-ray near-edge spectroscopy of phyllosilicate-sulfate mineral assemblages, including natrojarosite, from the Matanomadh Formation (Palaeocene) of the Kutch region in Gujarat, India. The unit-cell parameters of sulfate minerals and VNIR spectral properties are consistent with natrojarosite and other minerals. The mineralogy and unit-cell parameters indicate supergene or hydrothermal alteration conditions within the Kutch region. The Fe oxidation record (Fe3+/total Fe ∼0.83) is quantified using Fe K-edge XANES. Additionally, the Fe-S bond length for natrojarosite is determined to be 3.158 Å, and the experimental result fits well with the modeled iron sulfate data curve. The occurrences of natrojarosite and associated natroalunite and kaolinite in the post-Deccan volcanic province are consistent with an oxidizing environment and periodic shift of humid to arid environments that appear to be similar to the early geologic history of Mars. The oxidative alteration of pyrite further enhances the formation of natrojarosite. Our results, in concert with earlier studies, highlight the formation process of natrojarosite and provide insights into detailed mineralogy at the Kutch region and the magnitude of the redox state. The natrojarosite and the associated minerals (including anhydrite and other sulfates) argue for acidic and water-limited conditions analogous to the Noachian-Hesperian epoch of Mars, with implications for past weathering processes.

¹Addi Bischoff et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70060]
¹Institut für Planetologie, University of Münster, Münster, Germany
Published by arrangement with John Wiley & Sons

On October 24, 2024, an impressive fireball was visible over Austria. After the possible strewn field was calculated, the first sample of the Haag meteorite, with a mass of 8.76 g, was discovered on November 2, 2024, 8 days after the fireball event. Four more samples were found afterward putting the total sample mass at about 151 g. Short-lived radionuclides were measured shortly after recovery on a small sample, which was also used for almost all analyses presented here. Results confirm that the Haag meteorite derived from the bolide fireball event. Haag is a severely fragmented ordinary chondrite breccia and consists of typical equilibrated and recrystallized lithologies (LL4-6) as well as impact-related lithic clasts, such as dark, fine-grained impact breccias. Most fragments are highly recrystallized (type 6), but some show a well-preserved chondritic texture, which is of petrologic type 4 since the olivines are equilibrated. The olivines in the bulk rock have Fa contents of 29.5 ± 0.5 mol%, whereas the low-Ca pyroxenes have compositions of Fs23.9±1.4Wo1.6±0.7 with slightly variable Fs contents up to 28 mol%. However, the occurrence of type 3 fragments in other parts of the rock cannot completely be ruled out. Many clasts are moderately shocked (S4; C-S4). Using the fragment with the lowest degree of shock to determine the bulk rock’s shock degree, Haag has an overall shock degree of S2 (C-S2). The LL chondrite classification is also supported by O isotope data, the results of bulk chemical analysis, and the physical properties of density and magnetic susceptibility. The nucleosynthetic Ti and Cr isotope data confirm that Haag is an ordinary chondrite, related to the noncarbonaceous (NC) meteorites. Haag does not contain detectable amounts of solar wind-implanted noble gases, and we rule out any substantial exposure at the direct surface of the parent body. Based on noble gases, Haag has an exposure age of 21–24 Ma and a pre-atmospheric meteoroid radius of 20–85 cm with a sample depth between 4 and 5 cm below the meteoroid surface, consistent with constraints from cosmogenic radionuclides. The soluble organic compositions of Haag are consistent with the profiles of the Stubenberg (LL6) breccia and show characteristics consistent with the complex shock, brecciation, and lithification history of the breccia. Haag and Stubenberg fell near each other (110 km away) within just 8 years. Since only 8.5% (about 110) of meteorite falls worldwide are LL chondrites, it is remarkable that two LL chondrites fell near each other in such a short time.

¹I. Baziotis,^2,3L. Ferrière,⁴C. Ma,⁴J. Hu,⁵D. Palles,⁴P. D. Asimow
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70054]
¹Department of Natural Resources Management and Agricultural Engineering, Agricultural University of Athens, Athens, Greece
²Natural History Museum Vienna, Vienna, Austria
³Natural History Museum Abu Dhabi, Abu Dhabi, United Arab Emirates
⁴Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
⁵Theoretical & Physical Chemistry Institute, National Hellenic Research Foundation, Athens, Greece
Published by arrangement with John Wiley & Sons

We report new results from a study of shock-related features in the L6 ordinary chondrites Northwest Africa (NWA) 4672 and NWA 12841. Our observations confirm the occurrence of eight high-pressure (HP) minerals in each meteorite, namely, ringwoodite, majorite, akimotoite, wadsleyite, albitic jadeite, lingunite, tuite, and xieite. Based on the calibration of phase stability fields and majorite chemical variations from static experiments, we estimate peak shock conditions of 18–23 GPa and 1800–2100°C. However, both meteorites also contain minerals thought to record lower pressures, 14–18 GPa for wadsleyite, and possibly ~11.5 GPa for albitic jadeite. These are interpreted to have formed by cooling during partial release from the peak shock state. Although the presence of discrete shock melt veins demands spatial heterogeneity in the temperature field, we interpret the record of HP mineralogy in terms of temporal rather than spatial variation in pressure–temperature conditions during the shock and release event. Specifically, we infer that the cooling of shock melt veins to their liquidus occurred near peak pressure, whereas decompression began before the melt veins reached their solidus. NWA 4672 and NWA 12841 also display dense networks of shock melt veins, metal–sulfide segregations, and dark shock zones, implying a high density of pre-existing weak zones and, thus, a high likelihood of fragmentation during atmospheric entry. A comparison with the Suizhou L6 chondrite, in which a total of 26 HP phases have been identified, suggests that differences in the identification and number of observed HP polymorphs mostly reflect differences in the completeness and spatial scale of analytical studies rather than a true difference in the intensity of shock processing. It remains quite likely that many shocked L chondrites host more HP phases than have been recognized so far. These new results indicate a need for further high-resolution studies of L chondrites to distinguish between observational bias and true variations in the range of shock states they experienced.

¹Léna Jossé,¹Zélia Dionnet,¹Alice Aléon-Toppani,¹Rosario Brunetto,²Andrew King,³Emmanuel Gardés,⁴Eva Heripré,^1,5Damien Loizeau,¹Sasha Cryan,⁶Kentaro Hatakeda
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70056]
¹Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale (IAS), Orsay, France
²SOLEIL Synchrotron, Gif-sur-Yvette, France
³Laboratoire Magmas et Volcans (LMV), Université Clermont Auvergne, CNRS, IRD, Clermont-Ferrand, France
⁴Procédés et Ingénierie en Mécanique et Matériaux (PIMM), Arts et Métiers Sciences et Technologies, CNRS, CNAM, Paris, France
⁵Qualisat, Bièvres, France
⁶Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Japan
Published by arrangement with John Wiley & Sons

Extraterrestrial breccia samples are formed through impact-related processes that combine the fragments of distinct lithologies. As such, they are valuable indicators of the complex formation and evolution history of planetesimals in our solar system. Samples from asteroid (162173) Ryugu, returned to the Earth by the Hayabusa2 mission in December 2020, were characterized as breccias. The boundaries of mineralogical assemblages are typically drawn manually based on interpreted results from specific techniques, mostly performed on artificially produced 2D surfaces. This process inherently introduces subjectivity. Here, we present a semi-automated analytical method using synchrotron radiation micro X-ray computed tomography (SR-μXCT) data, called the Local Histogram method. It enables an unsupervised detection and 3D visualization of a few tens to hundreds of micrometer-sized lithologies showing sub-micrometer heterogeneities. We developed the method on a millimeter-sized Ryugu sample (A0159) in combination with a more traditional global grayscale threshold segmentation. In A0159, we report five distinct lithologies. They were confirmed and further characterized by an additional scanning electron microscopy (SEM) analysis on Xenon plasma-focused ion beam (Xe-pFIB) produced sections. Some lithologies show specific relationships with large fractures, while one is particularly enriched in sub-micrometer sulfides. A0159 is rich in carbonates and hosts the largest millimeter-scale dolomite vein seen on Ryugu.

¹B. Marty,¹L. Zimmermann,¹E. Füri,¹D. V. Bekaert,²J. J. Barnes,³A. N. Nguyen,^3,4,5H. C. Connolly,²D. S. Lauretta

Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70058]
¹CNRS, CRPG, UMR 7358, Université de Lorraine, Nancy, France
²Lunar and Planetary Laboratory, The University of Arizona, Tucson, Arizona, USA
³ARES (Astromaterials Research and Exploration Science), NASA Johnson Space Center, Houston, Texas, USA
⁴Department of Geology, Rowan University, Glassboro, New Jersey, USA
⁵Department of Earth and Planetary Science, American Museum of Natural History, New York, New York, USA
Published by arrangement with John Wiley & Sons

We report the elemental and isotopic abundances of all stable noble gases (helium, neon, argon, krypton, and xenon) in eight particles from asteroid Bennu returned by NASA’s OSIRIS-REx mission. We also report nitrogen abundances and isotopic ratios that were analyzed alongside neon and argon in four additional Bennu particles. These analyses confirm the similarities of Bennu material with Ivuna-type carbonaceous (CI) chondrites. The nitrogen isotopic compositions show intra- and inter-particle variations, pointing to the heterogeneous distribution of various N-bearing phases, while the abundances of nitrogen are within the range of those measured in CIs. Noble gas data indicate mixing between Q-like noble gases (a ubiquitous noble gas component found in most classes of primitive meteorites, presumably formed by noble gas incorporation into organic materials within the ionized regions of the parent cloud or in the protoplanetary disk) and various presolar components originally hosted by refractory grains that survived the high enthalpy birth of the solar system. The noble gases also include secondary contributions of three types: (i) noble gas isotopes produced by radioactivity, (ii) solar wind implantation, mostly identified in the light noble gas (He and Ne) isotopic compositions, and (iii) cosmogenic noble gases produced by interaction with high-energy cosmic rays, permitting us to estimate how long fresh surfaces were irradiated. We find that cosmic ray exposure (CRE) durations of Bennu material vary mostly between 1 and 3 Ma. These CRE ages are consistent with (i) radionuclide studies suggesting surface exposure for 2–7 Ma, (ii) small crater retention ages of 1.6–2.2 Ma, and (iii) the 1.75 ± 0.75 million years that Bennu is estimated to have been dynamically decoupled from the asteroid belt. In contrast to CRE ages, we find a maximum duration of solar wind irradiation of ≤100,000 a, in agreement with exposure duration of <85,000 a from solar energetic particle tracks and microcrater densities. The noble gas abundances in Bennu and Ryugu samples are higher by a factor ≥2 compared to CI meteorites, whereas their isotopic compositions are similar. This difference between material sampled directly from asteroids and their meteoritic equivalent suggests degradation of the latter through contact with the terrestrial environment. Neon–argon variations point to a potential genetic relationship between Bennu, Ryugu, CI materials on the one hand, and the terrestrial atmosphere on the other.

¹S. A. Singerling,²A. J. Brearley
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70061]
¹Schwiete Cosmochemistry Laboratory, Goethe University, Frankfurt, Germany
²Department of Earth and Planetary Sciences, MSC-03 2040, 1 University of New Mexico, Albuquerque, New Mexico, USA
Published by arrangement with John Wiley & Sons

We conducted a scanning electron microscopy (SEM) and transmission electron microscopy (TEM) study of sulfide–metal assemblages (SMAs) in minimally to moderately altered CR2 chondrites. The assemblages occur on chondrule rims and consist of kamacite cores rimmed by pyrrhotite. The kamacite and pyrrhotite share orientation relationships, arguing for a genetic link. The SMAs contain secondary alteration products, including nanoscale magnetite at the sulfide–metal interface (minimally altered SMAs) and magnetite, serpentine, nanoscale Ni-rich metal at metal–magnetite interfaces, and Ni,S-bearing reaction fronts within magnetite (moderately altered SMAs). We argue the SMAs initially formed in the solar nebula from the separation of immiscible metal and silicate melts followed by sulfidization of the metal. Aqueous alteration on the asteroidal parent body caused the kamacite to transform into magnetite and the magnetite to transform into serpentine. Alteration of kamacite to magnetite occurred under oxidizing and alkaline conditions, whereas alteration of magnetite to serpentine occurred under reducing, alkaline, and higher aSiO2 conditions. Serpentinization of magnetite appears to be a relatively common process in some carbonaceous chondrites. Additionally, theoretical and experimental studies are needed that simulate the oxidation of metal by H2O gas and water and also serpentinization of magnetite to form serpentine with variable Mg-Fe contents.

¹Gabriel Zachén,¹Carl Alwmark,¹Sanna Alwmark,^2,3Ludovic Ferrière,^4,5Roger H. Hewins
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70051]
¹Department of Geology, Lund University, Lund, Sweden
²Natural History Museum Vienna, Vienna, Austria
³Natural History Museum Abu Dhabi, Abu Dhabi, United Arab Emirates
⁴IMPMC, MNHN, UMR CNRS 7590, Sorbonne Université, Paris, France
⁵Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey, USA
Published by arrangement with John Wiley & Sons

Mesosiderites are rare, differentiated meteorites, so-called stony-iron meteorites—they are impact breccias composed of an unusual mix of crustal basalt and pyroxenite, core-derived metal, but no mantle materials. This odd mixture makes their origin enigmatic and has inspired many different formation theories over the last several decades. Some of the outstanding questions have regarded the origin of the metal, whether it came from another celestial body or from within the main parent body, and the puzzlingly low abundance, or absence, of mantle material in mesosiderites. The role of impacts has been central to most of the suggested theories, but mesosiderites show little to no evidence of shock metamorphism. The mystery of the origin of mesosiderites is further compounded by the relatively limited amount of published data, as well as the restricted number of samples available for research. With the detailed investigation and reclassification of the mesosiderites Lamont, Acfer 265, Queen Alexandra Range 86900 (QUE 86900), and MacAlpine Hills 88102 (MAC 88102) presented herein, our new observations shine some much-needed light on this meteorite group. Based on their petrologic and metamorphic characteristics, Lamont is classified as a B3/4, Acfer 265 and QUE 86900 as A1, and MAC 88102 as an A4 mesosiderite. The observation of multiple sets of parallel thin lamellae in high-Ca plagioclase and cristobalite in Lamont, and a silicate emulsion in QUE 86900 is proposed to be shock-related features. In both Lamont and QUE 86900, these features are interpreted to be subsequent to the initial impact, which mixed crustal and core material, and prior to deep burial. No shock-related features were noted in Acfer 265 and MAC 88102.

^1,2C. S. Harrison,¹A. J. King,²R. H. Jones,³L. Piani
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70052]
¹Planetary Materials Group, Natural History Museum, London, UK
²Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
³Centre de Recherches Pétrographiques et Géochemiques CNRS, Université de Lorraine, Metz, France
Published by arrangement with John Wiley & Sons

Phosphate minerals are significant carriers of volatiles (e.g., OH) and halogens in chondritic material; however, their origin in most groups of carbonaceous chondrites remains poorly characterized. We have determined the abundance, morphology, texture, and composition of phosphate grains in aqueously altered CI chondrites and in hydrated and thermally metamorphosed Antarctic CY chondrites using scanning electron microscopy and electron probe microanalysis. Phosphates include apatite (formula Ca5(PO4)3X, where X = F-, Cl-, OH- or other anions) and sodium-bearing magnesium phosphate, both of which formed during episodes of aqueous alteration on the CI and CY parent bodies. Apatite grains in the CI chondrites range up to 40 μm in size with a modal abundance of ~0.10 area%, while in the CYs, the largest grains are ~50 μm in size and the modal abundance is ≤0.70 area%. Analysis by secondary ion mass spectrometry (SIMS) indicates that apatite in the CYs contains ~1.0–1.8 wt% H2O, with δD values of −84‰ to 393‰ likely reflecting aqueous and thermal processing. Apatite in both the CI and CY chondrites is rich in fluorine, with fluorine abundances that range from 20 to 80 mole% of the X (anion) site. This contrasts with apatite in other chondrite groups, which is predominantly Cl-rich. Estimated bulk chondrite F abundances based on F abundance in apatite are 12–21 ppm F for the CI chondrites and 61 ppm F for the CY chondrites. This is comparable to bulk CI chondrite F abundances in the literature, suggesting that most fluorine is hosted in apatite. However, the chlorine content of CI chondrite apatite (<0.05 wt%) is too low to account for the bulk chondrite Cl abundance, indicating that Cl is hosted in other phases. Mg,Na-phosphate, a rare extraterrestrial mineral, has a modal abundance of ~0.02 area% in both the CI and CY chondrites. Mg,Na-phosphates in the CI and CY chondrites are halogen-poor (<0.15 wt%) and are typically hydrated in the CIs (analytical totals as low as 67 wt%) and dehydrated in the CYs (analytical totals >96.0 wt%). The occurrence of Mg,Na-phosphates in the CI and Antarctic CY chondrites is indicative of brines on their respective parent bodies. Similarities between the two groups, as well as with the phosphate mineral assemblage in asteroids Ryugu and Bennu, indicate that comparable fluid compositions and environmental conditions were prevalent on numerous parent bodies in the early Solar System.