^1,2Zhi Li,^1,3Ying-Kui Xu,^4,5Shui-Jiong Wang,⁴Si-Zhang Sheng,^1,3Shi-Jie Li,^1,3Xiong-Yao Li,^1,3Jian-Zhong Liu,⁶Dan Zhu
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14369]
¹Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
²College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
³CAS Center for Excellence in Comparative Planetology, Hefei, China
⁴State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences (Beijing), Beijing, China
⁵Frontiers Science Center for Deep-Time Digital Earth, China University of Geosciences (Beijing), Beijing, China
⁶State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
Published by arrangement with John Wiley & Sons

High-energy impact events prevalent during planetary accretion in the solar system’s evolution significantly shaped planetary bodies, though the effects of shock metamorphism on nickel (Ni) isotope fractionation remain unclear. To investigate the effect of the shock process on Ni isotopes, we selected three shocked ordinary chondrites (OCs) and obtained three sample pairs, each consisting of a melted region and its corresponding unmelted region. We also prepared two whole rock samples and four pairs of magnetic and coupled nonmagnetic samples. The shock melt pockets (SMPs) from three shocked OCs (Chelyabinsk LL5, Viñales L6, Tassédet 004 H5) show δ⁶⁰Ni values of 0.15 ± 0.05‰, 0.14 ± 0.02‰, and 0.20 ± 0.04‰, while adjacent unmelted parts show δ⁶⁰Ni values of 0.21 ± 0.03‰, 0.19 ± 0.01‰, and 0.19 ± 0.03‰. These data are slightly higher than the BSE value (0.11 ± 0.01‰) but generally overlap with the Ni isotopic variation of OCs (0.15–0.51‰) reported in previous studies. The SMPs do not show discernible isotopic variations relative to coupled unmelted parts, suggesting that shock-induced evaporation could not cause Ni isotope fractionation. The value of bulk OCs is calculated by compiling data from previous and this study, yielding a value of ‰0.21−0.11+0.28‰. Moreover, no consistent Ni isotopic variations from four pairs of magnetic and nonmagnetic counterparts are observed. Several possible processes resulting in Ni isotopic variations are discussed. A slight negative correlation between S content and Ni isotopic composition, along with a positive correlation between Ni elemental and isotopic composition in shocked OCs, suggests that the Ni isotopic characteristics may be predominantly influenced by the relative proportions of metal and sulfide phases.

¹Masaaki Miyahara,²Takaaki Noguchi,³Akira Yamaguchi,¹Toru Nakahashi,¹Yuto Takaki,^2,4Toru Matsumoto,⁵Naotaka Tomioka,²Akira Miyake,²Yohei Igami,⁶Yusuke Seto
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14370]
¹Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, Japan
²Division of Earth and Planetary Sciences, Kyoto University, Kyoto, Japan
³National Institute of Polar Research, Tokyo, Japan
⁴The Hakubi Center for Advanced Research, Kyoto University, Kyoto, Japan
⁵Kochi Institute for Core Sample Research, X-star, JAMSTEC, Nankoku, Japan
⁶Department of Geosciences, Osaka Metropolitan University, Osaka, Japan
Published by arrangement with John Wiley & Sons

Djerfisherite, a K-bearing Fe-Ni sulfide, was identified in grain C0105-042 collected from the subsurface of asteroid Ryugu through SEM and TEM analyses. The mineral occurs as an isolated crystal embedded within a matrix of Mg-Fe phyllosilicates. Although djerfisherite is known to form as a condensate phase in enstatite chondrites and aubrites, its mode of occurrence in Ryugu grain C0105-042 is markedly different. Two possible origin scenarios are considered: (i) an extrinsic origin, in which a djerfisherite fragment derived from enstatite chondrites or aubrites was deposited onto asteroid Ryugu, and (ii) an intrinsic origin, where djerfisherite formed in situ through a localized reaction between K-bearing hot fluid or vapor and Fe-Ni sulfide under reducing alkaline conditions within asteroid Ryugu’s body. Isotopic data, which could directly constrain its origin, are currently unavailable; thus, the origin of djerfisherite remains unresolved. Nonetheless, this finding suggests the presence of exotic material or localized chemical heterogeneities within Ryugu’s body, offering new insights into the complex evolutionary processes that shaped primitive bodies in the early Solar System.

¹Naotaka Tomioka,^2,3Kosuke Kurosawa,⁴Akira Miyake,⁴Yohei Igami,⁵Takayoshi Nagaya,⁴Takaaki Noguchi,⁴Toru Matsumoto,⁶Masaaki Miyahara,⁷Yusuke Seto
American Mineralogist 110, 945-955 Link to Article [https://doi.org/10.2138/am-2024-9540]
¹Kochi Institute for Core Sample Research, X-star, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Nankoku, Kochi 783-8502, Japan
²Department of Human Environmental Science, Graduate School of Human Development and Environment, Kobe University, 3-11, Tsurukabuto, Nada-ku, Kobe, Hyogo 657-8501, Japan
³Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, Chiba 275-0016,Japan
⁴Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
⁵Department of Environmental Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501, Japan
⁶Earth and Planetary Systems Science Program, Graduate School of Advanced Science and Engineering, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
⁷Department of Geosciences, Graduate School of Science & School of Science, Osaka Metropolitan University, Sumiyoshi-ku, Osaka 558-8585, Japan
Copyright: The Mineralogical Society of America

Shock recovery experiments were performed using a two-stage light gas gun to clarify the progressive deformation microstructures of calcite at the submicrometer scale concerning pressure. Decaying compression pulses were produced using a projectile that was smaller than the natural marble target. In two experiments, natural marble samples were shocked to 13 and 18 GPa at the epicenters of the targets. Calcite grains shocked in the pressure range of 1.1–18 GPa were examined using polarized light microscopy and (scanning) transmission electron microscopy. The density of free dislocations in the grains shocked at 1.1–2.2 GPa [108–9 (cm−2)] is comparable to that of unshocked Carrara calcite grains. Subparallel bands of entangled dislocations <1 μm are formed at 4.2 GPa, and strongly entangled dislocations spread throughout the focused ion beam (FIB) sections at 7.3–18 GPa. Dislocations selectively nucleate and entangle near the slip planes at pressures above ∼3 GPa, corresponding to the transition from sharp extinction to undulatory extinction, according to the microstructural evolution with shock pressure. Above ∼6 GPa, the dislocations nucleated homogeneously throughout the calcite crystals. The dislocation microstructure in a calcite grain collected from the asteroid Ryugu particle is similar to that of the experimentally shocked calcite at 4.2 GPa. The estimated pressure of 2–3 GPa, determined through fault mechanics analyses and the presence of dense sulfide minerals in the Ryugu particles, is in line with this pressure.

¹Sylvain Laforet,¹Hugues Leroux,¹Corentin Le Guillou,²Maya Marinova,¹Adrien Néri,¹Adrien Teurtrie,¹Francisco de la Peña,¹Damien Jacob,²Alexandre Fadel,³David Troadec
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14366]
¹Université de Lille, CNRS, INRAE, Centrale Lille, UMR 8207-UMET-Unité Matériaux et Transformations, Lille, France
²Université de Lille, CNRS, INRAE, Centrale Lille, Université Artois, FR 2638-IMEC-Institut Michel-Eugène Chevreul, Lille, France
³Université de Lille, CNRS, Centrale Lille, Junia, Univ. Polytechnique Hauts-de-France, UMR 8520 – IEMN – Institut d’Electronique de Microélectronique et de Nanotechnologie, Lille, France
Published by arrangement with John Wiley & Sons

The first few microns of the surface of airless bodies are subject to severe changes due to the harsh environment of space, known as space weathering. The Hayabusa2 sample return mission from the asteroid Ryugu provides the first opportunity to study these effects on a carbonaceous and hydrated body. Understanding the structural and chemical changes that occur in the space weathered layers of Ryugu is crucial to correctly interpreting the mechanisms involved in such processes. This study employs transmission electron microscopy to achieve the spatial resolution necessary to analyze the nanoscale heterogeneities in these modified layers. The chemical analyses indicate that features present are likely to represent the spattering of a Ryugu-like material, possibly from a different lithology of the asteroid. However, such material appears to be completely dehydroxylated and depleted in sulfur by approximately 20%. Furthermore, the nanoscale dispersion of vesicles and rounded nanosulfides found in these melt layers helps to estimate the temperatures (>1300°C) and the time scales (<10−8 s) involved in their formation. In addition, this study describes and discusses a unique spherical feature not previously observed in Ryugu samples. The 3 μm-sized object shows strong similarities to microchondrules observed in some carbonaceous (CM2) and ordinary chondrites, suggesting a divergent thermal history from that of the melt layers.

¹M. V. Goryunov et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14368]
¹Institute of Physics and Technology, Ural Federal University, Ekaterinburg, Russian Federation
Published by arrangement with John Wiley & Sons

The iron-bearing phases and crystals within (i) the bulk interior and the fusion crust from Tamdakht H5 and (ii) the bulk interior from Annama H5 ordinary chondrites were studied by optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction (XRD), magnetization measurements, and Mössbauer spectroscopy. The main iron-bearing phases/crystals such as olivine, orthopyroxene, clinopyroxene, troilite, chromite, and hercynite, as well as Fe-Ni-Co alloy with the α2-Fe(Ni, Co), α-Fe(Ni, Co) and γ-Fe(Ni, Co) phases were identified in both meteorites. XRD and Mössbauer spectroscopy showed high contents of Fe-Ni-Co alloy in the bulk interiors from Tamdakht H5 and Annama H5 ordinary chondrites. The fusion crust from Tamdakht H5 contains a new phase of magnesioferrite. A classification scheme for H, L, and LL ordinary chondrites using the relative areas of Mössbauer spectral components was applied to these meteorites’ classification. The ratios of the M1 and M2 site occupations by Fe2+ in olivine and orthopyroxene were determined using XRD and Mössbauer spectroscopy, showing consistent results. The equilibrium cation distribution temperatures for olivine and orthopyroxene in Tamdakht H5 and Annama H5 were determined using XRD and Mössbauer spectroscopy.

¹Shuai Li, ^2,3,4Daniel P. Moriarty III, ⁵Carle M. Pieters, ⁶Rachel L. Klima, ⁶Angela M. Dapremont
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116668]
¹Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, HI, USA
²NASA Goddard Space Flight Center, Greenbelt, MD, USA
³Department of Astronomy, University of Maryland, College Park, MD, USA
⁴Center for Research and Exploration in Space Science & Technology II, University of Maryland, College Park, MD, USA
⁵Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, USA
⁶Johns Hopkins University Applied Physics Laboratory (JHUAPL), Laurel, MD, USA
Copyright ELsevier

This study presents high-resolution (140 m/pixel) controlled mosaics of Moon Mineralogy Mapper (M3) data in the lunar polar regions (80°–90° N/S), with a focus on assessing mineralogy and water content across the Artemis exploration zone. M3 extensively sampled the lunar polar regions, providing a high spatial resolution, hyperspectral imaging dataset that uniquely covers reflectance absorptions of major minerals and water on the lunar surface. We developed a methodology to preferentially use M3 image cubes acquired when the star tracker was operational to ensure accurate spatial registration of M3 pixels in our new mosaics. Integrated band depth (IBD) analyses were conducted to map distributions of hematite and other mineral species at the Artemis exploration zone. We also derived water contents at the Artemis sites from our new M3 mosaics. Our findings indicate that the Artemis exploration zone is largely dominated by mature regolith that is probably rich in plagioclase. Hematite is predominantly concentrated on east-facing slopes, likely due to enhanced oxidation from Earth wind oxygen interacting with the lunar regolith. Pyroxene-rich exposures are observed in three Artemis candidate landing regions and they are all associated with fresh impact craters. The water distribution is highly variable, with higher concentrations on pole-facing slopes and near permanently shadowed regions, likely controlled by low surface temperatures. High water contents are observed at hematite exposures, which reinforces that water may play a crucial role in hematite formation on the Moon. These results provide valuable insights for future lunar exploration, aiding in the selection of landing sites, planning of traverse routes, and informing in situ resource utilization (ISRU) for the Artemis missions.

^1,2,3Kengo T.M. Ito, ¹Sota Niki, ⁴Hikaru Hasegawa, ¹Kanoko Kurihara, ²Tokiyuki Morohoshi, ⁴Takashi Mikouchi, ¹Takafumi Hirata, ⁵Martin Bizzarro, ²Tsuyoshi Iizuka
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.05.022]
¹Geochemical Research Center, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan
²Department of Earth and Planetary Science, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan
³Division of Sustainable Energy and Environmental Engineering, The University of Osaka, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan
⁴The University Museum, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan
⁵Center for Star and Planet Formation, Globe Institute, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen, Denmark
Copyright Elsevier

Brachinites are a group of primitive achondrites composed mostly of ferroan olivine, which may have formed as partial melting residues or cumulates on an incompletely differentiated planetesimal. To constrain the petrogenetic origin of brachinites and the thermal history of the parent body, we report the first study that integrates mineralogical, rare earth element (REE), and U–Pb age data for brachinite Ca-phosphates, apatite and merrillite, using very coarse grains up to ∼ 500 µm in diameter found in Northwest Africa 10932. The mineralogical data reveal partial replacement of apatite by merrillite concurrent with the reaction of olivine and a S-rich vapor to form symplectitic clinopyroxene-troilite/Fe-Ni metal intergrowths during thermal metamorphism. Apatite cores surrounded by merrillite rims exhibit REE zoning resulting from diffusion during metamorphism. Diffusion modeling of the REE zoning using the olivine-chromite equilibration temperature of 978 ± 11 ˚C constrains the duration of the metamorphism to be 104 yr. This timescale is far longer than that of shock metamorphism, and therefore requires an internal heat source such as adjacent magma. The apatite cores and merrillite rims yielded identical U–Pb ages of 4482 ± 29 Ma (2σ) reflecting complete resetting of the U–Pb system during metamorphism. This metamorphic age is distinctly younger than the Mn–Cr age of 4565 Ma reported for the Brachina meteorite, revealing indigenous thermal activity over ∼ 80 Myr on the parent body. Reconciling the protracted thermal activity with the primitive brachinite composition suggests that brachinites were derived from a moderately shallow region of the parent body, whose interior was differentiated into a core and mantle. Moreover, the metamorphic age is identical to the reported U–Pb age of apatite in the andesitic meteorites Graves Nunataks 06128 and 06129 [4460 ± 30 Ma (2σ)]. This correspondence supports the hypothesis that the andesitic meteorites are samples of partial melts extracted from the ultramafic residues represented by brachinites and further suggests that the transformation from apatite to merrillite in the brachinite source region released a metasomatic Cl-rich fluid to form chlorapatite in the shallower crustal region.

¹Zichen Wei, ¹Yan Zhuang, ^1,2Hao Zhang, ³Pengfei Zhang, ³Yang Li, ⁴Menghua Zhu, ¹Te Jiang, ³Ronghua Pang
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116665]
¹School of Earth Sciences, China University of Geosciences, Wuhan, China
²CAS Center for Excellence in Planetology, Hefei, China
³Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
⁴State Key Laboratory of Lunar and Planetary Science, Macau University of Science and Technology, Macau, China
Copyright Elsevier

Space weathering processes, including micrometeoroid impact and solar wind irradiation typically redden, darken, and attenuate the fingerprint absorption features in the visible and near-infrared (VNIR) reflectance spectra of planetary surface materials. The so-called lunar style space weathering typically produces nanophase metallic iron (npFe0) and amorphous mineral layers. This paradigm has been known to be inadequate in describing the weathering processes on many other airless bodies and many open questions are waiting to be answered. For example, the greater flux of micrometeorite impacts or higher surface temperature on Mercury may produce larger npFe0 particles; the gardening effects on space weathering remain largely unknown; on asteroids such as Vesta, random regolith mixing and contamination by exogenic material from impacts are believed to be the dominant space weathering processes. To understand these and other questions in non-lunar style space weathering, we conducted pulsed laser irradiations on low-iron olivine grains in powders and pellets at various energy levels. By performing transmission electron microscope and reflectance spectroscopic measurements, we found that progressive irradiation caused continuous darkening. Meanwhile, the VNIR spectral slope changed from reddening to bluing after reaching a “saturation point”, and the absorption band depth transitioned from weakening to stabilization. At the same time, repeated irradiations led to limited growth of npFe0 particles in low-iron olivine. In all simulated irradiations, significant spectral alterations occurred in early stages, implying that fresh surfaces are more sensitive to space weathering. The rates of spectral modification of powder samples were found to be remarkably lower than those of the pellet samples. We also observed that exogenous metal contaminants could evaporate and condense into an opaque layer during simulated bombardments, obscuring the original spectral features of regolith.

¹Torii Douglas-Song, ¹Tsutomu Ota, ¹Masahiro Yamanaka, ¹Hiroshi Kitagawa, ¹Ryoji Tanaka, ¹Christian Potiszil, ¹Tak Kunihiro
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.05.038]
¹The Pheasant Memorial Laboratory Institute for Planetary Materials, Okayama University Yamada 827, Misasa, Tottori 682-0193, Japan
Copyright Elsevier

Here we report the in situ ion-microprobe analyses of the Li- and O-isotope compositions of enstatite, FeO-rich pyroxene, olivine, glass, and cristobalite grains from six chondrule-related objects from the Sahara 97103 EH3 chondrite. The O-isotope composition of the enstatite grains scattered around the intersection between the terrestrial fractionation and primitive chondrule minerals lines. Whereas, that of olivine varied along the primitive chondrule minerals line. Based on the mineralogy, we found cristobalite formed as a result of Si saturation, instead of the reduction of FeO-rich silicates, consistent with Si-enrichment of whole rock enstatite chondrites. Based on the mineralogy and O-isotope compositions, we infer that olivines in some chondrules are relict grains. In chondrules that contained olivine, no abundant niningerite [(Mg,Fe,Mn)S] was observed. Thus, enstatite formation can be explained by the interaction of an olivine precursor with additional SiO2 (Mg2SiO4 + SiO2 → Mg2Si2O6), instead of sulfidation (Mg2SiO4 + S → 1/2 Mg2Si2O6 + MgS + ½O2). Using the equation Mg2SiO4 + SiO2 → Mg2Si2O6 and the O-isotope compositions of enstatite and olivine, the O-isotope composition of the additional SiO2 was estimated. Based on the O-isotope composition, we infer that there could be a Si-rich gas with an elevated Δ17O value similar to, or greater than the second trend line (Δ17O = 0.9 ‰) suggested by Weisberg et al. (2021), during chondrule formation. The variation in the Li-isotope compositions of enstatite and olivine grains from EH3 chondrules is smaller than that for the same phases from CV3 chondrules. The variation in the Li-isotope compositions of the enstatite and olivine grains from EH3 chondrules is also smaller than that of their O-isotope compositions. During the recycling of enstatite-chondrite chondrules, both Li- and O-isotope compositions were homogenized. Although enstatite is the major carrier of Li in EH3 chondrules, the Li-isotope composition (δ7Li) of enstatite is lower than that of whole rock EH3 chondrites, suggesting the existence of a phase with higher δ7Li. Meanwhile, the Li-isotope composition and concentration (δ7Li, [Li]) of enstatite is higher than that of olivine. The Li-isotope composition of the Si-rich gas was estimated to be δ7Li = 1 ‰, using a similar mass-balance calculation as applied for the O-isotope composition. The Li-isotope composition of the Si-rich gas from the enstatite-chondrite-chondrule forming-region, is consistent with that of whole rock EH3 chondrites, and differs significantly from that of the Si-rich gas from the carbonaceous-chondrite-chondrule-forming region (δ7Li = −11 ‰) determined by a previous study. We speculate that the Si-rich gas in the carbonaceous-chondrite-chondrule-forming region maintained the Li-isotope heterogeneity inherited from light lithium synthesized by galactic cosmic-ray spallation in the interstellar medium.

¹Samuel Ebert, ³Kazuhide Nagashima, ²Alexander N. Krot, ¹Addi Bischoff
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.05.029]
¹Institut für Planetologie, University of Münster, Münster, Germany
²Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
Copyright Elsevier

Refractory inclusions [Ca,Al-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs)] in unmetamorphosed chondrites (petrologic type ≤ 3.0) have typically uniform 16O-rich solar-like compositions. The origin of oxygen-isotope heterogeneity within individual refractory inclusions from weakly metamorphosed (petrologic type > 3.0) chondrites remains controversial. It may reflect (i) condensation from a nebular gas having variable O-isotope composition, (ii) gas–solid or gas–melt O-isotope exchange with this gas, and/or (iii) O-isotope exchange with an 16O-depleted aqueous fluid in the host chondrite parent bodies. Here, we present the mineralogy, petrology and O-isotope compositions of refractory inclusions (12 CAIs and 2 AOAs) from the Rumuruti-type (R) chondrites of petrologic type 3 – Northwest Africa (NWA) 753, NWA 1471, and Dhofar 1123. The CAIs and AOAs are extensively altered: melilite is completely replaced by secondary minerals; perovskite is largely replaced by ilmenite; spinel and olivine are enriched in FeO. The polymineralic refractory inclusions have heterogeneous O-isotope compositions: Δ17O ranges from ∼−25 ‰ to ∼5 ‰ (2σ = ±∼2‰). The only exception is a spinel-hibonite inclusion having uniform 16O-depleted composition (Δ17O ∼ −14 ‰). Hibonite, most ferroan spinel, and some olivine and Al,(Ti)-diopside grains in Rumuruti-type chondrite (RC) fragments of low petrologic type (3.15 − 3.2) retained their initial Δ 17O values, which, however, range from −25 ‰ to ∼ −14 ‰, suggesting variations in O-isotope composition of nebular gas in the CAI-forming region. Most Al,Ti-diopside and some olivine and spinel grains in RC refractory inclusions are 16O-depleted compared to minerals most resistant to O-isotope exchange (hibonite and spinel) that retained their original compositions. The most 16O-depleted compositions of Al,Ti-diopside and ferroan olivine have Δ17O of ∼ +5‰ that is similar to Δ17O of the aqueously formed grossular and ferroan olivine. We infer that the 16O-depleted Al,Ti-diopside, olivine, and spinel in isotopically heterogeneous refractory inclusions experienced post-formation O-isotope exchange with aqueous fluids in the RC parent asteroid(s).