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We present here an investigation of Ryugu particles recovered by the Hayabusa2 space mission and their extracted carbonaceous acid residues using Raman spectroscopy. Raman parameters of Ryugu intact grains and their acid residues are characterized by broad D (defect induced) and G (graphite) band widths, indicating the presence of polyaromatic carbonaceous matter with low thermal maturity. Raman spectra of Ryugu particles and CI (type 1) chondrites exhibit stronger laser‐induced fluorescence backgrounds compared to Type 2 and Type 3 carbonaceous chondrites. The high fluorescence signatures and wide bandwidths of the D and G bands of Ryugu intact grains are similar to the Raman spectra observed in CI chondrites, reflecting the low structural order of their aromatic carbonaceous matter, and strengthening the link between Ryugu particles and CI chondrites. The high fluorescence background intensity of the Ryugu particles is due to multiple causes, but it is likely that the relative abundance of geometry‐bearing macromolecular organic matter in total organic carbon contents makes a large contribution to the fluorescence intensities. Locally observed high fluorescence in the acid‐extracted residues of Ryugu is due to nitrogen‐bearing outlier phase. The high fluorescence signature is one consequence of the low degree of thermal maturity of the organic matter and supports evidence that the Ryugu particles have escaped significant parent body thermal metamorphism. [ABSTRACT FROM AUTHOR]

The infrared spectral characteristics of organic‐rich acid residues prepared from Ryugu samples returned by the JAXA Hayabusa2 mission generally match those from unheated carbonaceous chondrite meteorites, but the residues from Ryugu are richer in methyl and methylene functional groups and have higher CH2/CH3 ratios. Moreover, two distinct outlier carbonaceous phases are found; one with spectral characteristics of N‐H functional groups, likely amides, and a second phase containing less nitrogen. Such infrared characteristics of Ryugu organic matter might indicate the pristine nature of the freshly collected samples and reflect the near‐surface chemistry in the parent asteroid. [ABSTRACT FROM AUTHOR]

Context. The current period is conducive to exploring our Solar System's origins with recent and future space sample return missions, which provide invaluable information from known Solar System asteroids and comets The Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) recently brought back samples from the surface of the Ryugu carbonaceous asteroid. Aims. We aim to identify the different forms of chemical composition of organic matter and minerals that constitute these Solar System primitive objects, to shed light on the Solar System's origins. Methods. In this work, we recorded infrared (IR) hyper-spectral maps of whole-rock Ryugu asteroid samples at the highest achievable spatial resolution with a synchrotron in the mid-IR (MIR). Additional global far-IR (FIR) spectra of each sample were also acquired. Results. The hyper-spectral maps reveal the variability of the functional groups at small scales and the intimate association of phyl-losilicates with the aliphatic components of the organic matter present in Ryugu. The relative proportion of column densities of the identified IR functional groups (aliphatics, hydroxyl + interlayer and/or physisorbed water, carbonyl, carbonates, and silicates) giving access to the composition of the Ryugu samples is estimated from these IR hyper-spectral maps. Phyllosilicate spectra reveal the presence of mixtures of serpentine and saponite. We do not detect anhydrous silicates in the samples analysed, at the scales probed. The carbonates are dominated by dolomite. Aliphatics organics are distributed over the whole samples at the micron scale probed with the synchrotron, and intimately mixed with the phyllosilicates. The aromatic C=C contribution could not be safely deconvolved from OH in most spectra, due to the ubiquitous presence of hydrated minerals. The peak intensity ratios of the organics methylene to methyl (CH2/CH3) of the Ryugu samples vary between about 1.5 and 2.5, and are compared to the ratios in chondrites from types 1 to 3. Overall, the mineralogical and organic characteristics of the Ryugu samples show similarities with those of CI chondrites, although with a noticeably higher CH2/CH3 in Ryugu than generally measured in C1 chondrites collected on Earth, and possibly a higher carbonate content. [ABSTRACT FROM AUTHOR]

Dmitrywanovite (Ca[Al.sub.2][O.sub.4]) is a newly described, calcium aluminum oxide from the Northwest Africa 470 (NWA470) CH3 chondrite (Ivanova et al. 2002). NWA470 contains abundant small Ca,Al-rich inclusions (CAIs), and dmitryivanovite, whose composition is close to stoichiometric Ca[Al.sub.2][O.sub.4] [[Ca.sub.1.000][([Al.sub.1.993][Si.sub.0.003][Ti.sub.0.002]).sub.1.998] [O.sub.4]], was found in one of these CAIs. It occurs as ~10 [micro]m subhedral grains intergrown with grossite (Ca[Al.sub.4][O.sub.7]), perovskite, and melilite. Electron backscatter diffraction (EBSD) analysis revealed that dmitryivanovite is a high-pressure polymorph of Ca[Al.sub.2][O.sub.4] (a = 7.95, b = 8.62, c = 10.25 [Angstrom], [beta] 93.1 [degrees], space group [P2.sub.1]/c, and Z = 12). Dmitryivanovite is the third phase to be described from nature in the binary system of CaO-[Al.sub.2][O.sub.3], the other two being hibonite (Ca[Al.sub.12][O.sub.19])and grossite (Ca[Al.sub.4][O.sub.7])--all are found in CAIs. The presence of (Ca[Al.sub.2][O.sub.4]) in NWA470 suggests a local elevated dust/gas ratio in the solar nebula. The phase diagram of (Ca[Al.sub.2][O.sub.4]) shows that ~2 GPa is required to stabilize the high-pressure (Ca[Al.sub.2][O.sub.4]) polymorph at 1327[degrees]C, above which (Ca[Al.sub.2][O.sub.4]) condenses from the solar nebula. Because it is unlikely that the solar nebula ever had such a high total gas pressure, it appears more probable that condensation of the low-pressure polymorph occurred in the solar nebula with an enhanced dust-to-gas ratio and that subsequently the high-pressure polymorph was produced by shock metamorphism, most likely after the (Ca[Al.sub.2][O.sub.4])-bearing CAI was incorporated into the NWA470 parent asteroid. Keywords: Dmitryivanovite, CAI, electron backscatter diffraction, new minerals, CH chondrite

Meteoritical Bulletin 110 contains the 2802 meteorites approved by the Nomenclature Committee of the Meteoritical Society in 2021. It includes 10 falls (Arpu Kuilpu, Djadjarm, Glendale, Kindberg, Madura Cave, Motopi Pan, Orconuma, Punggur, Tihigrin, Winchcombe), with 2014 ordinary chondrites (including 1 ungrouped ordinary chondrite), 220 carbonaceous chondrites (including 11 ungrouped), 212 HED achondrites, 69 lunar meteorites, 62 ureilites, 43 iron meteorites, 35 Martian meteorites, 31 Rumuruti chondrites, 27 primitive achondrites, 24 mesosiderites, 19 relict meteorites (all iron meteorites), 15 pallasites, 13 enstatite chondrites, 11 ungrouped achondrites, 7 enstatite achondrites. Of the meteorites classified in 2021, 1270 are from Antarctica, 1049 from Africa, 329 from South America, 123 from Asia, 20 from North America, 6 from Europe, 3 from Oceania, and 2 from unknown locations. [ABSTRACT FROM AUTHOR]

We explore impact shock processing of the regolith of parent asteroids of carbonaceous chondrites, which has not been considered a major process for hydrous carbonaceous chondrites. We describe shock‐produced minerals and features found in brecciated CI, CM, and CV chondrites, including agglutinates, a glassy melt pod, a shock melt vein, and melted sulfides. We also reexamine cognate clasts present in the Vigarano CV3 chondrites which appear to derive from asteroid ponds and exhibit cross‐bedded dish structures. [ABSTRACT FROM AUTHOR]

Our goal was to devise a bridge between shock determinations of asteroid regolith grains by standard light optical petrography, synchrotron X‐ray diffraction (SXRD), and electron backscattered diffraction (EBSD). We determined the optimal conditions under which to measure the shock stage of olivine crystals in astromaterial grains by EBSD. We applied this EBSD procedure to the shock stage determination of four regolith grains from asteroid Itokawa, returned to earth by the Hayabusa spacecraft. Interpretation of these data required a parallel examination of three ordinary chondrite standards that exhibited shock histories ranging from stage 2 to stage 4, using all three techniques. Standard light optical petrography indicated shock stage of S2/3 for the 24 Itokawa grains analyzed. SXRD results for seven Itokawa grains indicate a shock stage of S2. EBSD maps of four Itokawa grains indicate shock stage S3. Thus, the different techniques indicate slightly different shock stages, probably due to small sampling populations for EBSD and SXRD. We therefore recommend that significantly more than seven regolith grains should be separately analyzed by any shock determination technique, probably between 10 and 20. In any case, Itokawa regolith grains have been shocked to stage S2/3, or approximately 5–10 GPa. Finally, we investigated the crystallinity of one Itokawa olivine by SXRD, determining that the 5–10 GPa shock it had experienced did not appreciably alter the size of the unit cell, contrary to some previous suggestions. [ABSTRACT FROM AUTHOR]

Meteoritical Bulletin 109 contains the 2790 meteorites approved by the Nomenclature Committee of the Meteoritical Society in 2020. It includes 17 falls (Al Farciya, Auckland, Cavezzo, Flensburg, Gatuto, Kolang, Mahadeva, Matarka, Narashino, Novo Mesto, Oslo, Saint‐Ouen‐en‐Champagne, Santa Filomena, Tarda, Tiros, Wad Lahteyba, Zhob), with 2336 ordinary chondrites, 131 carbonaceous chondrites (including 8 ungrouped ones), 123 HED achondrites, 41 Martian meteorites, 35 lunar meteorites, 23 iron meteorites, 21 ureilites, 17 primitive achondrites, 13 ungrouped achondrites, 12 mesosiderites, 12 Rumuruti chondrites, 9 enstatite chondrites, 8 pallasites, 4 unclassified meteorites (identified at the surface of Mars), 3 enstatite achondrites, 1 angrite, and 1 ungrouped chondrite. One thousand five hundred and forty‐one are from Antarctica, 763 from Africa, 297 from South America, 127 from Asia, 31 from North America, 11 from Europe, 10 from Oceania, 9 from Mars, and 1 from an unknown location. [ABSTRACT FROM AUTHOR]

MnO/FeO ratios in olivine from amoeboid olivine aggregates ( AOAs) reflect conditions of nebular condensation and can be used in concert with matrix textures to compare metamorphic conditions in carbonaceous chondrites. LIME (low-iron, Mn-enriched) olivine was identified in AOAs from Y-81020 ( CO3.05), Kaba ( CV~3.1), and in Y-86009 ( CV3), Y-86751 ( CV3), NWA 1152 ( CR/ CV3), but was not identified in AOAs from Efremovka ( CV3.1-3.4) or Allende ( CV>3.6). According to thermodynamic models of nebular condensation, LIME olivine is stable at lower temperatures than Mn-poor olivine and at low oxygen fugacities (dust enrichment <10× solar). Although this set of samples does not represent a single metamorphic sequence, the higher subtypes tend to have AOA olivine with lower Mn/Fe, suggesting that Mn/Fe decreases during parent body metamorphism. Y-81020 has the lowest subtype and most forsteritic AOA olivine (Fo>95) in our study, whereas Efremovka AOAs are slightly Fe-rich (Fo>92). AOA olivines from Kaba are mostly forsteritic, but rare Fe-rich olivine precipitated from an aqueous fluid. A combination of precipitation of Fe-rich olivine and diffusion of Fe into primary olivine grains resulted in iron-rich compositions (Fo97-59) in Allende AOAs. Variations from fine-grained, nonporous matrix toward higher porosity and coarser lath-like matrix olivine can be divided into six stages represented by (1) Y-81020, Efremovka, NWA 1152; (2) Y-86751 lithology B; (3) Y-86009; (4) Kaba; (5) Y-86751 lithology A; (6) Allende. These stages are inferred to represent general degree of metamorphism, although the specific roles of thermally driven grain growth and diffusion versus aqueous dissolution and precipitation remain uncertain. [ABSTRACT FROM AUTHOR]

Based upon our characterization of three separate stones by electron and X-ray beam analyses, computed X-ray microtomography, Raman microspectrometry, and visible- IR spectrometry, Sutter's Mill is a unique regolith breccia consisting mainly of various CM lithologies. Most samples resemble existing available CM2 chondrites, consisting of chondrules and calcium-aluminum-rich inclusion (CAI) set within phyllosilicate-dominated matrix (mainly serpentine), pyrrhotite, pentlandite, tochilinite, and variable amounts of Ca-Mg-Fe carbonates. Some lithologies have witnessed sufficient thermal metamorphism to transform phyllosilicates into fine-grained olivine, tochilinite into troilite, and destroy carbonates. One finely comminuted lithology contains xenolithic materials (enstatite, Fe-Cr phosphides) suggesting impact of a reduced asteroid (E or M class) onto the main Sutter's Mill parent asteroid, which was probably a C class asteroid. One can use Sutter's Mill to help predict what will be found on the surfaces of C class asteroids such as Ceres and the target asteroids of the OSIRIS- REx and Hayabusa 2 sample return missions (which will visit predominantly primitive asteroids). C class asteroid regolith may well contain a mixture of hydrated and thermally dehydrated indigenous materials as well as a significant admixture of exogenous material would be essential to the successful interpretation of mineralogical and bulk compositional data. [ABSTRACT FROM AUTHOR]

Samples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by the Hayabusa2 spacecraft. We investigated the macromolecular organic matter in Ryugu samples and found that it contains aromatic and aliphatic carbon, ketone, and carboxyl functional groups. The spectroscopic features of the organic matter are consistent with those in chemically primitive carbonaceous chondrite meteorites that experienced parent-body aqueous alteration (reactions with liquid water). The morphology of the organic carbon includes nanoglobules and diffuse carbon associated with phyllosilicate and carbonate minerals. Deuterium and/or nitrogen-15 enrichments indicate that the organic matter formed in a cold molecular cloud or the presolar nebula. The diversity of the organic matter indicates variable levels of aqueous alteration on Ryugu's parent body.