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An extraterrestrial origin for a carbonaceous, diamond-bearing and silicate-free stone named "Hypatia", found in 1996 in southwest Egypt, was determined in 2013 and confirmed in 2015 on the basis of argon, helium, neon, xenon and nitrogen isotope characteristics. Petrography and Raman spectroscopy has indicated that the parent body was primitive, i. e. not thermally processed in the solar nebula. Here we report the results of in situ chemical analyses of this object using proton induced X-ray emission (PIXE) spectroscopy. The stone has a bimodal matrix. Type 1 is essentially devoid of elements heavier than oxygen, whereas matrix 2 shows a unique, consistent element abundance pattern from aluminum to zinc, up to a sum of 4.5 wt%. Fe is dominant and Si markedly depleted, with a CI-chondrite normalized Si/Fe ratio of c. 0.1. Element abundance ratios to Fe show several correlations, with one group (Al, Si, K, Ca, Ti and Cu) being negatively correlated to another one (P, S and Ni). Since the parent body was primitive, magmatic differentiation cannot be invoked to account for any part of this dataset. Considering published Raman spectroscopic data and interstellar dust models, we hypothesize that Hypatia's parent body consisted of interstellar dust. However, Hypatia's matrix 2 chemistry does not fit predictions for the average interstellar dust composition based on absorption spectroscopic studies of element depletions in gas along stellar lines of sight. Instead, it shows similarities to the nucleosynthesis yields of specific supernova Ia models, whereby the element abundance correlations and the strong depletion of Si may be understood as resulting from nuclear photodisintegration. It has been known for decades that the chemistry of interstellar space is made up of many components, each bearing the signature of the nucleosynthesis processes giving rise to them. Now it appears from the case of Hypatia that an individual component was preserved in dust, and delivered to a region of the solar nebula where mixing did not obliterate it prior to the coagulation of larger bodies. • The parent body of the carbonaceous, extraterrestrial stone "Hypatia" was primitive. • We report proton microprobe analyses of elements Al to Zn in the object. • A consistent element abundance pattern includes Si/Fe and Mn/Fe 0.1 × the solar value. • Relative even-Z element abundances are similar to some modeled supernova Ia yields. • The results imply that matter forming the solar nebula included heterogeneous dust. [ABSTRACT FROM AUTHOR]

Abstract: We have studied a small, very unusual stone, here named “Hypatia”, found in the area of southwest Egypt where an extreme surface heating event produced the Libyan Desert Glass 28.5 million years ago. It is angular, black, shiny, extremely hard and intensely fractured. We report on exploratory work including X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy with EDS analysis, deuteron nuclear reaction analysis, C-isotope and noble gas analyses. Carbon is the dominant element in Hypatia, with heterogeneous O/C and N/C ratios ranging from 0.3 to 0.5 and from 0.007 to 0.02, respectively. The major cations of silicates add up to less than 5%. The stone consists chiefly of apparently amorphous, but very hard carbonaceous matter, in which patches of sub- diamonds occur. values (ca. 0‰) exclude an origin from shocked terrestrial coal or any variety of terrestrial diamond. They are also higher than the values for carbonaceous chondrites but fall within the wide range for interplanetary dust particles and comet 81P/Wild2 dust. In step heating, 40Ar/36Ar ratios vary from 40 to the air value (298), interpreted as a variable mixture of extraterrestrial and atmospheric Ar. Isotope data of Ne, Kr and Xe reveal the exotic noble gas components G and P3 that are normally hosted in presolar SiC and nanodiamonds, while the most common trapped noble gas component of chondritic meteorites, Q, appears to be absent. An origin remote from the asteroid belt can account for these features. We propose that the Hypatia stone is a remnant of a cometary nucleus fragment that impacted after incorporating gases from the atmosphere. Its co-occurrence with Libyan Desert Glass suggests that this fragment could have been part of a bolide that broke up and exploded in the airburst that formed the Glass. Its extraordinary preservation would be due to its shock-transformation into a weathering-resistant assemblage. [Copyright &y& Elsevier]

This is a follow-up study of a work by Kramers et al. (2013) on a very unusual diamond-rich rock fragment found in the area of south west Egypt in the south-western side of the Libyan Desert Glass strewn field. This pebble, called Hypatia, is composed of almost pure carbon. Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD) results reveal that Hypatia is mainly made of defect-rich diamond containing lonsdaleite and multiple deformation bands. These characteristics are compatible with an impact origin on Earth and/or in space. We also analyzed concentrations and isotopic compositions of all five noble gases and nitrogen in several ∼mg sized Hypatia samples. These data confirm the conclusion by Kramers et al. (2013) that Hypatia is extra-terrestrial. The sample is relatively rich in trapped noble gases with an isotopic composition being close to the Q component found in many types of meteorites. 40 Ar/ 36 Ar ratios in individual steps are as low as 0.4 ± 0.3 . Cosmic-ray produced “cosmogenic” 21 Ne is present in concentrations corresponding to a nominal cosmic-ray exposure (CRE) age of roughly 0.1 Myr if produced in a typical meter-sized meteoroid. Such an atypically low nominal CRE age suggests high shielding in a considerably larger body. In addition to the Xe–Q composition, an excess of radiogenic 129 Xe (from the decay of short-lived radioactive 129 I) is observed ( Xe 129 / Xe 132 = 1.18 + / − 0.03 ). Two isotopically distinct N components are present, an isotopically heavy component ( δ N 15 ∼ + 20 ‰ ) released at low temperatures and a major isotopically light component ( δ N 15 ∼ − 110 ‰ ) at higher temperatures. This disequilibrium in N suggests that the diamonds in Hypatia were formed in space rather than upon impact on Earth ( δ N atm 15 = 0 ‰ ). All our data are broadly consistent with concentrations and isotopic compositions of noble gases in at least three different types of carbon-rich meteoritic materials: carbon-rich veins in ureilites, graphite in acapulcoites/lodranites and graphite nodules in iron meteorites. However, Hypatia does not seem to be directly related to any of these materials, but may have sampled a similar cosmochemical reservoir. Our study does not confirm the presence of exotic noble gases (e.g. G component) that led Kramers et al. (2013) to propose that Hypatia is a remnant of a comet nucleus that impacted the Earth. [ABSTRACT FROM AUTHOR]