The CM2 meteorites Grove Mountains (GRV) 021536, Murchison, and Shidian, contain anhydrous lithic clasts that have been interpreted as fragments of a planetesimal linked to CM or CV group carbonaceous chondrites. Here we describe 57 lithic clasts in Cold Bokkeveld (CM2) that are strikingly similar to those in the other three CMs in their petrography, mineralogy, and chemical and isotopic compositions. The Cold Bokkeveld clasts are dominated by equilibrated olivine, with subordinate plagioclase feldspar (andesine), clinopyroxene (diopside), nepheline, a spinel-group oxide (ferrian chromite), pentlandite, pyrrhotite, troilite and merrillite. Their bulk chemical composition is chondritic, and olivine oxygen isotope values span a wide range, from delta 18O 3.6 %o Delta 17O-3.9 %o to delta 18O 20.3 %o Delta 17O 1.1 %o. Two clusters of clasts can potentially be distinguished from the chemical composition of their olivine: Fa38 and Fa41. The Fa38 cluster includes most of Cold Bokkeveld's clasts and is close in chemical composition to those described from GRV 021526 and Murchison. The Fa41 cluster is represented by the largest Cold Bokkeveld clast, and its olivine is compositionally comparable to that in Shidian. Anhydrous lithic clasts that occur in all four of the CM meteorites are likely to have been derived from a large planetesimal with CM and CY affinities that had undergone thermal metamorphism and metasomatism. The CV3 breccias Mokoia and Yamato 86009 contain anhydrous lithic clasts that are close in mineralogy and oxygen isotopic composition to those in the four CMs and so are likely to have been sourced from the same carbonaceous planetesimal or one with a similar geological history. The oxygen isotopic compositions of olivine in clasts from GRV 021536, Murchison, Shidian, Cold Bokkeveld, Mokoia and Yamato 86009 plot on a shared trendline in 3oxygen isotope space that connects the CV-CK-CO, CM, and CY fields thus suggesting genetic or evolutionary links between the five carbonaceous chondrite groups. The occurrence of these distinctive clasts in four CM2 meteorites could indicate that their parent body was the same rubble pile asteroid that had been built from aqueously altered and thermally metamorphosed lithologies.

Combining electron backscatter diffraction (EBSD) with X-ray computed tomography (XCT) offers a comprehensive approach to investigate shock deformation and rock texture in meteorites, yet such integration remains uncommon. In this study, we demonstrate the synergistic potential of XCT and EBSD in revealing deformation metrics, thereby enhancing our understanding of petrofabric strength and shock-induced deformation. Our analysis focuses on the Ozerki (L6, S4/5, W0) meteorite fall, which was instrumentally observed on June 21, 2018, and subsequently recovered by the Ural's branch of the Russian Fireball Network (UrFU) recovery expedition a few days later. The trajectory analysis conducted by the Finnish Fireball Network facilitated the prompt retrieval of the meteorite. We show that Ozerki is deformed, with a moderate strength foliation fabric defined by metal and sulfide grain shapes. Microstructural analysis using EBSD shows that the parent body was likely still thermally active during this impact event. Our data suggest that these microstructures were likely produced during an impact while the Ozerki's parent body was still warm.

A hydrous Ca-Fe-rich silicate identified as hydroandradite was observed in the "Mighei-type" carbonaceous (CM) chondrite falls, Shidian and Kolang. This is the first report of hydroandradite occurring within meteorites. Hydroandradite forms through aqueous calc-silicate alteration under specific fluid conditions. Its presence within Shidian and Kolang has implications for interpreting alteration processes within the C-complex asteroid parent bodies of the CM chondrites. To better understand its occurrence, the meteoritic hydroandradite was studied with scanning electron microscopy, electron probe microanalysis, transmission electron microscopy, and Raman spectroscopy. It occurs in four petrographic contexts: layered, perovskite-associated, sulfide-associated, and spheroidal. Kolang has all four morphologies, while only the sulfide-associated occurs in Shidian. In Kolang, hydroandraditewas likely produced by replacement of kamacite, Ti-bearing clinopyroxene in calcium- and aluminum-rich inclusions, and secondary magnetite in three distinct alteration events. The formation temperature of meteoritic hydroandradite was estimated to be 100-245 degrees C, based on the mineralogy of the lithologies within which it occurs as well as on its degree of hydration relative to synthetic and terrestrial hydroandradites. Because Kolang and Shidian are the only reported meteorites with hydroandradite to date, they may be from the same parent body.

Xenoliths in carbonaceous chondrites include lithologies that are unrepresented in the meteorite record and so are a rich source of information on asteroid diversity. Cold Bokkeveld is a CM2 regolith breccia that contains both hydrous and anhydrous lithic clasts. Here, we describe a hydrous clast with a fine-grained rim. This rim shows that the clast is a xenolith that interacted with dust in the protoplanetary disk between liberation from its protolith and incorporation into Cold Bokkeveld's parent body. Prior to its fragmentation, the xenolith's protolith had undergone brittle deformation, with the fractures produced being cemented by carbonates to make veins. After being incorporated into Cold Bokkeveld's parent body, the veined xenolith experienced a second phase of aqueous alteration leading to hydration of its fine-grained rim, replacement of carbonate by tochilinite-cronstedtite intergrowths, and formation of magnetite within its fine-grained matrix. The veined xenolith's protolith underwent its entire geological evolution (accretion-aqueous alteration-fracturing-fragmentation) before Cold Bokkeveld's parent body had accreted. Such a short lifespan may be explained by explosive breakup of the protolith due to overpressure from gases produced internally during water-rock interaction. Early fragmentation effectively acted as a thermostat to limit runaway heating that may have otherwise resulted from the body's high concentrations of 26Al. Many other hydrous lithic clasts in CM carbonaceous chondrite meteorites could be the remains of such ephemeral early asteroids, but they are hard to identify without evidence that they were accreted as hydrous lithologies and contemporaneously with chondrules.

Northwest Africa (NWA) 13669 is a recently found nakhlite and here, we use 2-D and 3-D mineralogy and texture, quantitative textural analysis of pyroxene, bulk rock and mineral major and trace element compositions, and melt inclusion analyses to assess its formation and emplacement. Using these combined results, we determine that NWA 13669 is derived from a depleted mantle source common to nakhlites and modeled parental melt compositions from olivine- and pyroxene-hosted melt inclusions record similar major element trends to other nakhlites, including an alkali enrichment. Homogeneous pyroxene and olivine and diffusive reequilibration of trace elements in melt inclusions provide evidence for magma storage in a crystal mush within the nakhlite plumbing system and suggest NWA 13669 has undergone extensive reequilibration. Quantitative textural analysis of NWA 13669, including crystal size distribution (CSD) profiles, CSD slope and intercepts, and residence times, are similar to the Yamato nakhlite group, and indicate that NWA 13669 likely experienced similar emplacement conditions. However, differences in bulk rock and mineral compositions suggest NWA 13669 represents a new flow or sill from a previously unsampled portion of the nakhlite igneous complex, further increasing the diversity of the nakhlite suite.

The Mighei-like carbonaceous (CM) chondrites have been altered to various extents by water-rock reactions on their parent asteroid(s). This aqueous processing has destroyed much of the primary mineralogy of these meteorites, and the degree of alteration is highly heterogeneous at both the macroscale and nanoscale. Many CM meteorites are also heavily brecciated juxtaposing clasts with different alteration histories. Here we present results from the fine-grained team consortium study of the Winchcombe meteorite, a recent CM chondrite fall that is a breccia and contains eight discrete lithologies that span a range of petrologic subtypes (CM2.0-2.6) that are suspended in a cataclastic matrix. Coordinated multitechnique, multiscale analyses of this breccia reveal substantial heterogeneity in the extent of alteration, even in highly aqueously processed lithologies. Some lithologies exhibit the full range and can comprise nearly unaltered coarse-grained primary components that are found directly alongside other coarse-grained components that have experienced complete pseudomorphic replacement by secondary minerals. The preservation of the complete alteration sequence and pseudomorph textures showing tochilinite-cronstedtite intergrowths are replacing carbonates suggest that CMs may be initially more carbonate rich than previously thought. This heterogeneity in aqueous alteration extent is likely due to a combination of microscale variability in permeability and water/rock ratio generating local microenvironments as has been established previously. Nevertheless, some of the disequilibrium mineral assemblages observed, such as hydrous minerals juxtaposed with surviving phases that are typically more fluid susceptible, can only be reconciled by multiple generations of alteration, disruption, and reaccretion of the CM parent body at the grain scale.

Lithification of artificial ground comprising by-products of legacy iron and steel workings presents a range of opportunities including atmospheric carbon dioxide (CO2) storage. The natural environmental processes altering these waste sites can also pose challenges such as ecotoxic metal leaching, and so it is important to characterise these largely undocumented anthropogenically-derived rocks. This study documents the lithification mechanisms, as well as mineralogical and geochemical characteristics across a legacy coastal iron and steel slag deposit (in Warton, England). X-Ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) analysis of the slag deposit, as well as thermogravimetric analysis (TGA) of the cream-coloured material covering the deposit, shows lithification both on the top surface and the seaward side above the mean high-water mark (MHWM), which is the result of carbonate mineralisation. This process is driven by water weathering slag minerals (gehlenite, åkermanite, and pseudowollastonite), which release calcium (Ca). Ingassed and hydroxylated atmospheric CO2 reacts with the leached Ca to form calcite that is slightly to strongly depleted in 13C (δ13C values: -6.4 ‰ to -22.7 ‰), following partial dissolved inorganic carbonate (DIC) equilibrium. Calcium-silicate-hydrate (CSH) precipitation was responsible for lithifying the deposit where more frequent and abundant seawater washing prevents subsequent slag mineral dissolution and carbonate precipitation. This work shows that legacy iron and steel slag deposits are prone to lithification, particularly in coastal settings. This lithification can draw down atmospheric CO2 and has the potential to slow the release of toxic metals from CSH precipitation, enhancing the possibility for repurposing legacy industrial waste for CO2 storage and coastal defence applications.

Nakhlites (clinopyroxene-rich cumulates) and chassignites (dunites) are two types of meteorites that were emplaced onto - and subsequently ejected from - the surface of Mars together, but their petrogenetic history has been difficult to discern. We studied the primary magmatic history preserved in zoning patterns of cumulus phases from a suite of nakhlites and chassignites. Samples studied include nakhlites Northwest Africa (NWA) 11013, NWA 10645, Governador Valadares, Caleta el Cobre 022, Nakhla, Miller Range 090032, and NWA 817, as well as chassignites NWA 2737 and Chassigny. In nakhlite and chassignite olivine, phosphorous (P) preserves primary magmatic signatures, and P2O5 ranges from similar to <0.01 - 0.21 wt %; in nakhlite pyroxene, chromium (Cr) zoning corresponds to Cr2O3 abundances between similar to 0.03 and 0.36 wt %. We find that nakhlite pyroxene cores uniformly formed rapidly for a time at high crustal pressures, and then slowly at near-equilibrium under lower crustal pressures. Pyroxene in the nakhlites were then stored through multiple injections of magma prior to remobilization, eruption, and final crystallization. Nakhlite olivine cores are morphologically heterogenous throughout the suite, but all record rapid initial crystallization prior to equilibrium formation, followed by resorption in changing magma compositions. Both olivine and pyroxene in the nakhlites are antecrysts, as they initially formed in a different magma than that in which they erupted. Chassignites underwent very rapid initial undercooling, and record later changes in magma conditions, resulting in thin elemental oscillatory zoning patterns in olivine grains. Together, the cumulus phases of the nakhlite and chassignite suite, combined with petrological evidence from martian shergottite meteorites, suggest that significant magmatic undercooling is the rule rather than the exception for martian magmatic systems. This may relate to the stalling of magmas within the thicker crust of Mars, fostering crystal storage with significant temperature differences between injected magmas and crystal mushes.

The alignment of non-spherical "flattened" chondrules into a petrofabric is a common feature of hydrated carbonaceous chondrite meteorites. This texture can form as a result of impacts at peak shock pressures exceeding 10 GPa. However, many carbonaceous chondrites with petrofabrics are unshocked. While several processes have been proposed to explain this incongruency, including erasure of shock effects by alteration (both aqueous and thermal), none have yet been confirmed. Kolang is a brecciated Mighei-like carbonaceous chondrite wherein analysis of chondrule shape and orientation shows that it has a pronounced petrofabric defined by elongate chondrules that is shared between clasts with differing aqueous and thermal alteration histories. Its petrofabric, therefore, must have developed after the altered clasts had been juxtaposed; any sign of shock associated with impact-driven deformation cannot have been erased. We have investigated the shock experienced by Kolang with a combination of traditional optical methods and electron backscatter diffraction. We find that the peak shock pressure experienced by Kolang was likely similar to 4-5 GPa, too low to generate an impact-induced petrofabric. Kolang has not experienced sufficient shock, whether by a single or multiple impacts, to deform its chondrules from spheres into elongate chondrules. The most likely explanation, therefore, is that Kolang accreted elongate chondrules that were aligned under relatively low pressure.

Many of the CM carbonaceous chondrites are regolith breccias and so should have abundant evidence for collisional processing. The constituent clasts of these fragmental rocks frequently display compactional petrofabrics; yet, olivine microstructures show that most CMs are unshocked. To better understand the reasons for this contradiction, we have sought other evidence for hypervelocity impact processing of CM chondrites using the Cold Bokkeveld meteorite. We find that this regolith breccia contains rare particles of vesicular shock melt that are close in chemical composition to bulk CM chondrite. Transmission electron microscopy of a melt bead shows that it is composed of silicate glass with inclusions of pentlandite, pyrrhotite, and w & uuml;stite. Characterization of shards of another bead by atom probe tomography reveals nanoscale clusters of sulfur that represent sulfide inclusions arrested at an early stage of growth. These glass particles are mineralogically comparable to micrometeoroid impact melt described from the Cb-type asteroid Ryugu and melt that has been experimentally produced by pulsed laser irradiation of CM targets. The glass could have formed by in situ shock-melting, but petrographic evidence is more consistent with an origin as ballistic ejecta from a distal impact. The scarcity of melt in this meteorite, and CM chondrites more broadly, is consistent with the explosive fragmentation of hydrous asteroids following energetic collisions. Cold Bokkeveld's parent body is likely to be a second-generation asteroid that was constructed from the debris of one or more earlier bodies, and only a small proportion of the reaccreted material had been highly shocked and melted.

To better understand volcanism on planetary bodies other than the Earth, the quantification of physical processes is needed. Here, the petrogenesis of the achondrite Martian Yamato (Y) nakhlites (Y 000593, Y 000749, and Y 000802) is reinvestigated via quantitative analysis of augite (high‐Ca clinopyroxene) phenocrysts: crystal size distribution (CSD), spatial distribution patterns (SDP), and electron backscatter diffraction (EBSD). Results from CSD and EBSD quantitative data sets show augite to have continuous uninterrupted growth resulting in calculated minimum magma chamber residence times of either 88–117 ± 6 yr or 9–12 yr. All samples exhibit low‐intensity S‐LS type crystallographic preferred orientation. Directional strain is observed across all samples with intracrystalline misorientation patterns indicative of (100)[001]:(001)[100] (Y 000593 and Y 000802) and {110}<001>or {110} 1 / 2 <110> (Y 000749) slip systems. SDP results indicate phenocryst‐bearing crystal‐clustered rock signatures. Combined findings from this work show that the Yamato nakhlites formed on Mars as individual low‐viscosity lava flows or sills. This study shows that through combining these different quantitative techniques over multiple samples, one can more effectively compare and interpret resulting data to gain a more robust, geologically contextualized petrogenetic understanding of the rock suite being studied. The techniques used in this study should be equally applicable to igneous achondrites from other parent bodies.

LaPaz Icefield (LAP) 02239 is a mildly aqueously altered CM2 carbonaceous chondrite that hosts a xenolith from a primitive chondritic parent body. The xenolith contains chondrules and calcium- and aluminum-rich inclusions (CAIs) in a very fine-grained matrix. The chondrules are comparable in mineralogy and oxygen isotopic composition with those in the CMs, and its CAIs are also mineralogically similar to the CM population apart for being unusually small and abundant. The presence of serpentine demonstrates that the xenolith has been aqueously altered, and its phyllosilicate-rich matrix has a comparable oxygen isotopic composition to the matrices of CM meteorites. The xenolith's chondrules lack fine-grained rims, whereas the xenolith itself has a fine-grained rim that is petrographically and chemically comparable with the rims on coarse grained objects in LAP 02239 and other CM meteorites. These properties show that the xenolith's parent body was formed from similar materials to the CM parent body(ies). Following its lithification by aqueous alteration, a piece of the xenolith's parent body was impact-ejected, acquired a fine-grained rim while free-floating in the protoplanetary disc, then was accreted along with rimmed chondrules and other materials to make the LAP 02239 parent body. Subsequent aqueous processing of the LAP 02239 parent body altered the fine-grained rims on the xenolith, chondrules, and CAIs. The xenolith shows that the timespan of geological evolution of carbonaceous chondrite parent bodies was sufficiently long for some of them to have been aqueously altered before others had formed.

CO2 mineralization in slag has gained significant attention since it occurs with minimal human intervention and energy input. While the amount of theoretical CO2 that can be captured within slag has been quantified based on slag composition in several studies, the microstructural and mineralogical effects of slag on its ability to capture CO2 have not been fully addressed. In this work, the CO2 uptake within legacy slag samples is analyzed through microstructural characterization. Slag samples were collected from the former Ravenscraig steelmaking site in Lanarkshire, Scotland. The collected samples were studied using X-ray Computed Tomography (XCT) to understand the distribution and geometry of pore space, as well as with scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) to visualize the distribution of elements within the studied samples. Electron backscatter diffraction (EBSD) was used to study the minerals distribution. The samples were also characterized through X-ray diffraction (XRD) and X-ray fluorescence (XRF), and the amount of captured CO2 was quantified using thermogravimetric analysis (TGA). Our results demonstrate that CO2 uptake occurs to the extent of-9-30 g CO2/ kg slag. The studied samples are porous in nature, with pore space occupying up to-30% of their volumes, and they are dominated by akermanite-gehlenite minerals which interact with the atmospheric CO2 slowly at ambient conditions. EDS and EBSD results illustrate that the precipitated carbonate in slag is calcite, and that the precipitation of calcite is accompanied by the formation of a Si-O-rich layer. The provided analysis concludes that the porous microstructure as well as the minerals distribution in slag should be considered in forecasting and designing large-scale solutions for passive CO2 mineralization in slag.