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"Iron meteorites"
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Iron from Tutankhamun's tomb
\"\"A century after Howard Carter and Lord Carnarvon's sensational discovery in 1922 of the virtually intact tomb of Tutankhamun in the Valley of the Kings, the boy-king and his treasures continue to fascinate people all over the world. Although nearly 5,400 objects accompanied the young pharaoh on his journey to the afterlife, many of them have not been investigated in detail. Iron from Tutankhamun's Tomb analyzes nineteen iron artifacts from the tomb in depth for the first time. This group consists of sixteen small iron chisels set into wooden handles, an Eye of Horus amulet, a miniature headrest, and the blade of a richly decorated golden dagger. The most important of these were placed in close proximity to the king's mummy, emphasizing the high value attributed to this rare material in late Bronze Age Egypt-a time when iron smelting was not yet known in the land of the Nile. Written by a research team of archaeologists, scientists, and conservators, this comprehensive study explores in fascinating detail the context and meaning of these artifacts, while establishing for the first time that Tutankhamun's iron came from meteorites. They complete their examination with the results of chemical analyses, offering in the process a rich overall understanding of iron and its significance in ancient Egypt.\"\"-- Provided by publisher.
Book
Mesosiderite formation on asteroid 4 Vesta by a hit-and-run collision
Collision and disruption processes of protoplanetary bodies in the early Solar System are key to understanding the genesis of diverse types of main-belt asteroids. Mesosiderites are stony-iron meteorites that formed by the mixing of howardite–eucrite–diogenite-like crust and molten core materials and provide unique insights into the catastrophic break-up of differentiated asteroids. However, the enigmatic formation process and the poorly constrained timing of metal–silicate mixing complicate the assignment to potential parent bodies. Here we report the high-precision uranium–lead dating of mesosiderite zircons by isotope dilution thermal ionization mass spectrometry to reveal an initial crust formation 4,558.5 ± 2.1 million years ago and metal–silicate mixing at 4,525.39 ± 0.85 million years ago. The two distinct ages coincide with the timing of the crust formation and a large-scale reheating event on the eucrite parent body, probably the asteroid Vesta. This chronological coincidence corroborates that Vesta is the parent body of mesosiderite silicates. Mesosiderite formation on Vesta can be explained by a hit-and-run collision 4,525.4 million years ago that caused the thick crust observed by NASA’s Dawn mission and explains the missing olivine in mesosiderites, howardite–eucrite–diogenite meteorites and vestoids.Mesosiderite meteorites may originate from a hit-and-run impact on the parent asteroid of eucrite meteorites (probably Vesta), as mesosiderite zircon U–Pb ages are found to coincide with those for eucrites.
Journal Article
Edscottite, Fe5C2, a new iron carbide mineral from the Ni-rich Wedderburn IAB iron meteorite
Edscottite (IMA 2018-086a), Fe5C2, is a new iron carbide mineral that occurs with low-Ni iron (kamacite), taenite, nickelphosphide (Ni-dominant schreibersite), and minor cohenite in the Wedder-burn iron meteorite, a Ni-rich member of the group IAB complex. The mean chemical composition of edscottite determined by electron probe microanalysis, is (wt%) Fe 87.01, Ni 4.37, Co 0.82, C 7.90, total 100.10, yielding an empirical formula of (Fe4.73Ni0.23Co0.04)C2.00. The end-member formula is Fe5C2. Electron backscatter diffraction shows that edscottite has the C2/c Pd5B2-type structure of the synthetic phase called Hägg-carbide, χ-Fe5C2, which has a = 11.57 Å, b = 4.57 Å, c = 5.06 Å, β = 97.7 °, V = 265.1 Å3, and Z = 4. The calculated density using the measured composition is 7.62 g/cm3. Like the other two carbides found in iron meteorites, cohenite (Fe3C) and haxonite (Fe23C6), edscottite forms in kamacite, but unlike these two carbides, it forms laths, possibly due to very rapid growth after supersaturation of carbon. Haxonite (which typically forms in carbide-bearing, Ni-rich members of the IAB complex) has not been observed in Wedderburn. Formation of edscottite rather than haxonite may have resulted from a lower C concentration in Wedderburn and hence a lower growth temperature. The new mineral is named in honor of Edward (Ed) R.D. Scott, a pioneering cosmochemist at the University of Hawai'i at Manoa, for his seminal contributions to research on meteorites.
Journal Article
Hidden mineral treasures in rust samples of the Muonionalusta iron (IVA) meteorite
Exceptionally well-developed crystals of akaganeite, (Fe3+,Ni2+)8(OH,O)16Cl1.25·nH2O, were observed during the investigation of rust samples from the Muonionalusta iron meteorite, constituting ideal candidates for the first single-crystal X-ray diffraction investigation carried out on this mineral. Other techniques here employed to study akaganeite include SEM-EDS and Raman spectroscopy. The structure refinement (R1 = 2.23%) confirmed akaganeite to be monoclinic in symmetry (space group I2/m), with a = 10.560(4) Å, b = 3.0268(12) Å, c = 10.512(4) Å, β = 90.050(15)° and V = 336.0(2) Å3. The mineral is also confirmed to be isostructural with monoclinic members of the hollandite supergroup, with 2 × 2 tunnels parallel to the b axis constituted by edge-linked Fe-octahedral chains. Chemical analyses resulted in a Cl range of 2.8-5.6 wt.% and an average mole Fe/Cl ratio of 7.6, with trace amounts of Si, Al and S (< 0.1 wt.%), and no detectable Ni or Co. The combination of structural and chemical data yielded the stoichiometric formula Fe8O7(OH)9Cl. The Raman spectrum of the Muonionalusta akaganeite is comparable with Raman spectra from synthetic akaganeite, showing several peaks between 138 and 1390 cm-1 and the O-H stretching band at 3510 cm-1; no peaks are observed in the H2O bending-mode area of the spectrum, in keeping with the structural data. Taking into account all the collected data, we propose two possible new formulae for akaganeite (Z = 8): FeO1-x(OH)1+xClx (0.01 < x < 0.20) or, taking Ni into account, (Fe1-xNix)O1-x-y(OH)1+x+yCly (0 < x < 0.19 and 0.01 < y < 0.20). In the Muonionalusta corrosion rust, in addition to akaganeite, nickel-bearing humboldtine [Fe(C2O4)·2H2O] was also identified through Raman spectroscopy, powder X-ray diffraction and chemical analyses. It possibly represents the first occurrence of an oxalate mineral as a product of terrestrial weathering of a meteorite.
Journal Article
Grokhovskyite, CuCrS2, a New Chromium Disulfide in Uakit Iron Meteorite (IIAB), Buryatia, Russia
Grokhovskyite, CuCrS2, was observed in small sulfide inclusions (up to 50–80 µm) in Ni-rich iron (kamacite) of the Uakit iron meteorite (IIAB) in the Republic of Buryatia, Russia. The grain sizes of this mineral are usually less than 5 μm, and the biggest detected crystals are 10 × 5 μm in size. It is commonly associated with daubréelite, troilite, schreibersite, and, sometimes, with carlsbergite and uakitite. Within inclusions, the mineral forms elongated splintered crystals, or, rarely, needle-shaped grains in daubréelite. The grokhovskyite-containing associations in the Uakit meteorite seem to form due to high-temperature (>1000 °C) separation of Fe-Cr sulfide liquid, which is locally enriched in Cu, from Fe-Ni metal melt. Physical and optical properties of grokhovskyite are quite similar to those of synthetic CuCrS2: yellow–brown and non-transparent phase with metallic luster; Mohs hardness ≈ 4; gray to light gray color with yellow tint in reflected light; weak to medium bireflectance, anisotropy, and pleochroism; density (calc.) = 4.559 g/cm3. Grokhovskyite is structurally related to the Cr-containing disulfide minerals with general formula Me+CrS2 (where Me+ = Na, Cu, Ag), including caswellsilverite, NaCrS2; schöllhornite, Na0.3CrS2·H2O; and cronusite, Ca0.2CrS2·2H2O. Structural data were obtained for one grokhovskyite crystal using the EBSD technique. Fitting of the EBSD patterns for a synthetic α-CuCrS2 model (trigonal R3m; a = 3.4794(8) Å; c = 18.702(4) Å; V = 196.08(10) Å3; Z = 3) resulted in the parameter MAD = 0.57–1.16° (good fit). Analytical data for grokhovskyite (n = 36, in wt.%) are as follows: Cu—32.97; Cr—27.65; Fe—3.69; Ni—0.16; S—35.71; Na, Zn, V, Mn, and Co—below detection limit (<0.005 wt.%). The empirical formula is (Cu0.930Cr0.952Fe0.118Ni0.005)2.005S1.995; however, different concentrations of Fe are indicated in two individual grains of grokhovskyite (0.09–0.17 apfu). Such variations may be explained by Fe incorporation in the grokhovskyite structure according to the scheme IVCu+ + VICr3+ → IVFe2+ + VIFe2+. The three main bands (near 110, 250, and 310 cm−1), which are common of synthetic CuCrS2, were observed in the Raman spectra of grokhovskyite.
Journal Article
XAFS and XRD study on Fe, Ni, and Ge in iron meteorite NWA 859
Iron meteorites record the evolutionary and cosmochemical processes of their parent bodies. Fe–Ni phases in iron meteorites show complex textures from various thermal histories of parent bodies as well as the phase relationships and crystal chemistry of Fe–Ni metal. Synchrotron radiation-based X-ray absorption fine structure spectra and X-ray diffraction were applied herein to the study of iron meteorite NWA 859 Fe, Ni, and Ge contents at the K-edge, since they are effective techniques in identifying crystal structures in iron meteorites. The bond distances of Fe and Ni in tetrataenite and kamacite were detected. Field-emission scanning electron microscopy and energy-dispersive spectroscopy were used to observe the petrological and chemical characteristics of the main minerals, kamacite and tetrataenite, and the trace mineral schreibersite. The tetrataenite phase and body-centered cubic kamacite formed a Widmanstätten pattern and cloudy zone. The extended X-ray absorption fine structure (EXAFS) analyses of NWA 859 and a single-crystal diffraction of tetrataenite show that it has a near-face-centered cubic (FCC) tetragonal structure with 12 nearest-neighboring Ni, Fe, and Ge atoms at distances of r
Ni-(Ni, Fe)
= 2.5170(13) Å, r
Fe-(Ni, Fe)
= 2.534(3) Å, and r
Ge-(Ni, Fe)
= 2.524(5) Å, respectively. Moreover, the X-ray absorption near-edge structure (XANES) spectra suggest that the Ge in tetrataenite exhibits a specific local structure with coordination number 12, suggesting that a new local structure of Ge-(Ni, Fe) was first discovered in extraterrestrial material, forming a stable tetragonal structure at approximately 688–618 K. X-ray absorption fine structure (XAFS) is an efficient technique that could provide us further information about local atomic structures and forming conditions in extraterrestrial materials without damage.
Journal Article
Minerochemical and Microtextural Study of the Ungrouped Iron Meteorite Oglat Sidi Ali, Eastern Highlands, Morocco, and Geomorphological Characterization of Its Strewnfield
Fragments of a new iron meteorite were found in and collected from Oglat Sidi Ali, Maatarka region, Morocco, during a series of expeditions in the years 2013–2017. The physical characteristics of recovered fragments feature typical attributes of individual samples of a unique meteorite strewnfield that originated from an iron meteorite shower via the fragmentation of a single body that broke up in the lower atmosphere. The total recovered mass of the Oglat Sidi Ali meteorite fragments was estimated to amount to more than 800 kg spread across a NE–SW oriented, 20 km-long and 5 km-wide strewnfield. Geochemical and mineralogical data achieved on Oglat Sidi Ali fragments, as well as the analysis of its microstructures obtained using electron backscattered diffraction (EBSD), suggested it should be classified as an ungrouped iron meteorite. A comparison of this meteorite with other ungrouped iron meteorites, such as NWA 859 and NWA 11010, purchased between 2001 and 2016 in various cities of Northeast Morocco show apparently similar mineralogy, geochemistry and textural features, suggesting a common origin from a single extraterrestrial body.
Journal Article
Joegoldsteinite; a new sulfide mineral (MnCr2S4) from the Social Circle IVA iron meteorite
Joegoldsteinite, a new sulfide mineral of end-member formula MnCr2S4, was discovered in the Social Circle IVA iron meteorite. It is a thiospinel, the Mn analog of daubreelite (Fe2+Cr2S4), and a new member of the linnaeite group. Tiny grains of joegoldsteinite were also identified in the Indarch EH4 enstatite chondrite. The chemical composition of the Social Circle sample determined by electron microprobe is (wt%) S 44.3, Cr 36.2, Mn 15.8, Fe 4.5, Ni 0.09, Cu 0.08, total 101.0, giving rise to an empirical formula of (Mn0.82Fe0.23)Cr1.99S3.95 The crystal structure, determined by electron backscattered diffraction, is a Fd3m spinel-type structure with a = 10.11 A, V = 1033.4 A3, and Z = 8.
Journal Article
Fe-Ni-P-S Melt Pockets in Elga IIE Iron Meteorite: Evidence for the Origin at High-Pressures Up to 20 GPa
Here we report new data on high-pressure microstructures in Elga group IIE iron meteorites, made of solidified Fe-Ni-P-S melt pockets and microcrystalline aggregates, which could be formed only at high pressures and temperatures according to the experimental data. The bulk composition of the melt pockets and crystals correspond to the Fe3P-Fe3S solid solution with the closure of an immiscibility gap at pressures near 20 GPa in static experiments. Some other melt pockets fit with the Fe2S-Fe2P compositions, which could also correspond to high pressures and temperatures. The results suggest a late shock episode during the formation of the IIE iron parent body, which may be prior or due to the final disruption that caused the meteorite arrival to Earth. It also has an important implication to the shock features in other meteorites, such as ureilite.
Journal Article
Evolution of the Dislocation Structure of Iron Meteorite
The state of the dislocation substructure of meteorite in which the history of phenomena accompanying the meteorite during its passage through the Earth’s atmosphere is recorded remains unused. The main goal of the presented work is a comprehensive analysis of the dislocation structure of the iron meteorite from the Morasko reserve (Poland, Wielkopolska Voivodeship) by TEM methods to determine the conditions and mechanism of its formation. The work is cognitive in the field of phenomena related to the destruction and deformation of the material in extreme conditions: space and terrestrial space. It can also be useful in the research on the creation of the material with specific mechanical properties, as well as a unique reference material for earth experiments with low-temperature deformation, high-speed deformation, recrystallization processes with short thermal pulses and structure relaxation in conditions of very long time periods.
Journal Article