In this study, we investigated the Almahata Sitta MS-170 section using transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS). Therefore, diamonds formed inside the UPB can potentially hold invaluable information about its size and composition. In terrestrial diamonds, this has allowed to estimate the depth of diamond formation, and to identify the composition and petrology of phases sampled at that depth. Owing to their stability, mechanical strength and melting temperature, diamonds very often encapsulate and trap minerals and melts present in their formation environment, in the form of inclusions. ![]() The formation of such large single-crystal diamond grains along with δ 15N sector zoning observed in diamond segments 7 is impossible during a dynamic event 8, 9 due to its short duration (up to a few seconds 10), and even more so by CVD mechanisms 11, leaving static high-pressure growth as the only possibility for the origin of the single-crystal diamonds. It was thus suggested that individual diamond single crystals as large as 100 μm existed in the sample, which have been later segmented through graphitization 7. Recent observation 7 of a fragment of the Almahata Sitta ureilite (MS-170) revealed clusters of diamond single crystals that have almost identical crystallographic orientation, and separated by graphite bands. There are three mechanisms suggested for diamond formation in ureilites: (i) shock-driven transformation of graphite to diamond during a high-energy impact 4, (ii) growth by chemical vapor deposition (CVD) of a carbon-rich gas in the solar nebula 5, and (iii) growth under static high-pressure inside the UPB 6. ![]() ![]() High concentrations of carbon distinguishes ureilites from all other achondrite meteorites 3, with graphite and diamond expressed between silicate grains. Ureilite fragments are coarse grained rocks mainly consisting of olivine and pyroxene, originating from the mantle of the ureilite parent body (UPB) 3 that has been disrupted following an impact in the first 10 Myr of the solar system 3. This exciting discovery could perhaps encourage some Arab countries to better appreciate these finds as real cultural assets and additions to their heritage, rather than taking advantage of them by selling them, as shown by the presence of about 1700 samples of Moroccan stars in foreign museums, spread around the world.Asteroid 2008 TC 3 fell in 2008 in the Nubian desert in Sudan 1, and the recovered meteorites, called Almahata Sitta, are mostly dominated by ureilites along with various chondrites 2. Several conditions are required for this transformation, including a temperature rising above no less than 2000°, an atmospheric pressure of at least 30 GPa (GigaPascal) and a sufficiently long collision time (a few seconds) to ensure the formation of diamond.Īll the elements were combined and thus changed NWA 12606 into an even rarer and more precious stone. Several very meticulous analyses were made on the rock before discovering these tiny diamonds, encrusted between different components (of millimetric dimensions!) such as olivine (at 90%), pyroxene (at 5%) or graphite (at 5%).īut how do diamonds end up in the universe? The formation of this gemstone comes in fact from the violent impact of the asteroid which crashes on the Earth, splitting the atmosphere: because of the extremely intense heat and pressure, the solid graphite inside the rock changes into diamond. Ureilites take their name from the Russian village Urey, where a similar meteorite landed in 1886. ![]() Its formation is believed to be four billion six hundred million years old, almost the same as the Sun and the planets! Classified in the family of the primitive achondrites, and more particularly in the sub-category of Ureilites, very rare stones which represent 0,6% of all the falls, it has a very particular mineralogical composition. This stone, which was found in 2018 in the Drâa-Tafilalet region, is extremely important for science: indeed, these star fragments are among the only elements that can offer us a glimpse at the History of the Universe. The meteorite had been exhibited in the Agadir Museum for two years, before Moroccan specialists, including Professor Ibhi, and their Italian colleagues decided to carry out a more in-depth analysis. Out of the 120 meteorites of various categories displayed in the museum, this fabulous discovery was made on NWA 12606.
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