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EN
Pallasites and mesosiderites belong to stony-iron meteorites and are representative matter of planetary siliceous and metallic alloys liquation zones. Pallasites origin most probably from frontier zones of parent asteroid between iron-nickel alloy core and mantle constituted of olivine, which was destructed during collisions and impacts. Unlike mesosiderites, pallasites parent body was disrupted probably after solidification of its differentiated interior. Asteroids: 201 Penelope, 250 Bettina and 337 Devosa are considered to be parent bodies of mesosiderites, while asteroids: 246 Asporina, 289 Nenetta and 446 Aeternitas are parent bodies of pallasites. Analysis of chemical composition of mesosiderites and pallasites and their comparison with chemical composition of the Earth’s crust allowed the authors to conclude on wealth of metallic resources on their parent bodies. Both pallasites and mesosiderites and in consequence the liquation zones of siliceous and metallic alloys from which these meteorites origin, have the highest abundances of PGM (Platinum Group of Metals) and Fe, Ni, Co, Cr, Au. Mesosiderites contain from several hundred thousand times to several hundred times more precious metals than the terrestrial crust. The highest enrichment can be observed for: Ru, Os, Pt, Re and Au. Moreover, Ni, Co, Ge and Cr have much higher concentrations in mesosiderites than in the Earth’s crust. Pallasites have the highest enrichment in precious metals as well (Ru, Ir, Os, Pt, Pd and Au). The higher concentration of Re, Ni, Co, Ge and Cr in pallasites than in the terrestrial crust was also observed. The higher abundances of Fe, Ni, Co, Au and Ir in bulk composition of mesosiderites and pallasites than in composition of CI chondrites, HED meteorites and the terrestrial crust give the evidence that crustal material composed of silicates during liquation processes lost most of these elements in favor to metallic alloys. The process of migration of elements and their liquating to metallic alloys was not done completely in the zone, where mesosiderites and pallasites origin, what indicate higher abundances of Fe, Ni and Co in silicates of stony-iron meteorites than in CI chondrites, HED meteorites and terrestrial crust.
PL
Pallasyty i mezosyderyty, należące do meteorytów żelazno-kamiennych, stanowią materię, która reprezentuje planetarne strefy odmieszania stopów krzemianowych i metalicznych. Pallasyty pochodzą najprawdopodobniej ze strefy granicznej między żelazowo-niklowym jądrem, a oliwinowym płaszczem planetoidy macierzystej, rozbitej w wyniku zderzeń i kolizji. W przeciwieństwie do mezosyderytów, planetoida macierzysta pallasytów została rozbita prawdopodobnie już po zastygnięciu jej zdyferencjonowanego wnętrza. Za ciała macierzyste mezosyderytów uważa się planetoidy: 201 Penelope, 250 Bettina i 337 Devosa, zaś pallasytów planetoidy: 246 Asporina, 289 Nenetta czy 446 Aeternitas. Analiza składu chemicznego mezosyderytów i pallasytów oraz jej porównanie ze składem skorupy ziemskiej pozwoliła autorom wyciągnąć wnioski dotyczące zasobności w surowce metaliczne ich ciał macierzystych. Zarówno pallasyty jak i mezosyderyty, a co za tym idzie strefy odmieszania stopów krzemianowych i metalicznych z których pochodzą te meteoryty, są najbardziej zasobne w platynowce oraz Fe, Ni, Co, Cr i Au. Mezosyderyty zawierają od kilkuset tysięcy razy do kilkuset razy więcej metali szlachetnych niż skorupa ziemska. Największe wzbogacenie zaobserwować można dla: Ru, Os, Pt, Re i Au. Także Ni, Co, Ge i Cr występują w mezosyderytach w koncentracjach znacznie większych niż w skorupie ziemskiej. Również pallasyty wykazują największe wzbogacenie w metale szlachetne – Ru, Ir, Os, Pt, Pd i Au. W dalszej kolejności wśród metali występujących w pallasytach w koncentracjach większych niż w skorupie ziemskiej wymienić należy: Re, Ni, Co, Ge i Cr. Większa zawartość Fe, Ni, Co, Au i Ir w uśrednionym składzie mezosyderytów i pallasytów niż w składzie chondrytów CI, meteorytów z klanu HED czy skorupie ziemskiej świadczy o tym, że przypowierzchniowe strefy ciał zdyferencjonowanych zbudowane z krzemianów podczas procesów odmieszania utraciły znaczną część tych pierwiastków na rzecz stopów metalicznych. Proces migracji pierwiastków i ich odmieszania do stopu metalicznego nie zaszedł prawdopodobnie do końca w strefach, z których pochodzą mezosyderyty i pallasyty na co wskazuje większa zawartość Fe, Ni i Co w krzemianach meteorytów żelazno-kamiennych niż w chondrytach CI, meteorytach klanu HED i skorupie ziemskiej. Także większa zawartość litofilnego Cr w stopie FeNi mezosyderytów i pallasytów niż w meteorytach żelaznych stanowi dowód na to, że nie uległ on całkowitemu odmieszaniu do stopu krzemianowego zgodnie ze swoim geochemicznym charakterem.
EN
In this article the authors present a simple method of determining the content of selected metal raw materials (Fe, Ni, Co) on the parent bodies of ordinary chondrites. Thanks to the use of planimeter for measuring, under microscope, polished slices of meteorites, it is possible to estimate quite accurately the proportion of these metals in the parent bodies of meteorites, i.e. on asteroids. When it comes to analysing a large number of polished slices, these results will be most likely comparable to much more expensive results of chemical tests conducted on meteorites. Based on the analysis of 16 thin polished sections and polished slices of 11 ordinary chondrites, the authors found out that the highest content of Fe, Ni and Co ore minerals, reaching 10,06% of the total volume, can be found in ordinary chondrites from group H. For ordinary chondrites from groups L and LL, it makes 3,86% and 3,93% of the volume respectively. Employing the results of chemical analyses available in literature sources, the authors also estimated the size of Fe, Ni and Co resources for several selected asteroids. These bodies contain higher concentrations of iron, nickel and cobalt than terrestrial deposits (those found in the earth’s crust). The total content of Fe on parent bodies of even the most deficient in metals group LL of ordinary chondrites is about twice as high as that in the earth’s crust. Cobalt occurs on parent asteroids of ordinary chondrites in concentrations 15–24 times as high as those in the earth’s crust, and the concentrations of Ni are 100–180 times as high as those in the earth’s crust. The contents of these metals on parent asteroids of ordinary chondrites are also several times as high as those in currently extracted deposits in the earth’s crust. Taking into account the mean annual terrestrial production of these metals, the authors have estimated that a parent asteroid of ordinary chondrites with the size between 433 Eros and 6 Hebe could satisfy our need for Fe, Ni and Co for the nearest several million to dozens of billion years. Considering the fact that asteroid belt contains plenty of such objects, and as many asteroids built chiefly of Fe-Ni alloy, one should regard this section of the Solar System as a practically inexhaustible source of metal raw materials. The prospect of their exploitation is probably much nearer than we can currently imagine.
EN
Based on petrological, mineralogical and geochemical research authors classified new meteorite Northwest Africa 11779 as the ordinary chondrite L6, S1, W1. Chemical composition of olivine crystals (Fa 24.9 mol.%) and of pyroxene crystals (Fs 19.4 mol.%) proved that this meteorite belongs to L chondrites. However, bulk chemical composition of NWA 11779 is not typical for L chondrites. Nevertheless, all analyzed elements (except Mo, Sn and Nb) are in abundances reported for L chondrites, some of elements have concentration closed to average abundances for L chondrites. The content of chosen, characteristic lithophile, siderophile and chalkophile elements in NWA 11779 chondrite is in most cases in accord with its typical abundance in L chondrites. Presence of poorly defined chondrules, secondary feldspar crystals larger than 50 µm in size, absence of glass within chondrules, coarse recrystallized matrix (with olivine crystals of 0.5 mm in diameter and pyroxene crystals of 0.3 mm in diameter) as well as carbon content below 0.2 wt% proved that studied meteorite belongs to the petrologic type 6. The only difference from characteristic features of petrologic type 6 in case of NWA 11779 chondrite is presence of ca. 10% of monoclinic Ca-poor pyroxenes. Undulatory extinction by olivine and absence of other shock features in this chondrite allow to determine the shock level as S1. Weathering grade of NWA 11779 was identified as W1 based on weathering of only FeNi alloy grains. The outer part of metallic grains as well as contact zones of FeNi and FeS are changed due to weathering. Between 10 and 20% of FeNi alloy grains are oxidized to iron oxides and hydroxides. These secondary products of weathering replace outer zone of FeNi grains and fill the small cracks, creating a few thin veins.
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EN
The authors drew attention to the classification in December 2022 of over one ton of lunar meteorites that fell to Earth. They have been found since the early 1960s, but their first classification, as lunar meteorites, was made only in 1982. This was possible thanks to more advanced geochemical research and the possibility of comparing their results with the results of analyzes of samples of rocks and lunar regolith brought by the Soviet missions of the Luna program, and above all by several American missions of the Apollo program. With access to over 1.4 tons of lunar rocks on Earth, we are now able to conduct multidisciplinary studies of the lunar geology. Their results are particularly important in the context of building human settlements or lunar bases for further exploration of the solar system. This applies to both the physical properties of these rocks, as well as their chemical and mineral composition in the context of the presence of deposits of various mineral resources. It should be emphasized that meteoritic material from the Moon has been increasing in terrestrial collections (especially scientific ones) very quickly since 2015. This is the result of extensive exploration work, primarily in Antarctica, Africa, the Arabian Peninsula and Australia. Among the identified rocks reaching the Earth in the form of lunar meteorites, the most numerous are feldspar breccias (impact metamorphic rocks), anorthosites (plutonic igneous rocks building highlands areas of the silver globe) and basalts (extrusive igneous rocks building areas of the lunar maria). In addition, there are other igneous mafic rocks, such as gabbro, norite, troctolite and others. The surface of the crust is covered with regolith composed of fragments of the above-mentioned igneous rocks and breccias subjected to fragmentation by successive collisions with meteorites and micrometeorites and the action of solar wind particles (space weathering). As a result of these processes, the surface of the Moon is covered with a layer of loose sedimentary rock with a thickness of a few to several meters. Locally, a regolith may be a compact clastic sedimentary rock if a significant number of rock fragments are welded together with the glaze produced during collisions with micrometeorites. The authors also briefly presented the genesis and evolution as well as the geological structure of the Moon based on the results of the latest geophysical and geochemical (including isotopic) as well as mineralogical and petrological research. They pointed out that the proposed model of the genesis of the Moon from synestia formed after the collision of the proto-Earth with another hypothetical planetary embryo called Theia, explains well the chemical and isotopic homogeneity of the Earth and the Moon. The authors also pointed out that due to the common genesis, lunar meteorites are classified and named in the same way as terrestrial rocks, which definitely distinguishes them from other meteorites. The exceptions are Martian and HED meteorites, which are classified similarly to terrestrial rocks, although their names often do not have equivalents in the classification of terrestrial rocks (e.g. SNC meteorites). Tracking data on officially classified lunar meteorites, the authors found that in December 2022, the total mass of meteoritic matter considered to coming from the Moon exceeded 1 ton. Lunar meteorites are currently the largest source of information about the geology of the Silver Globe, accounting for almost two-thirds of the mass of lunar material available for study on Earth.
PL
Autorzy zwrócili uwagę na sklasyfikowanie w grudniu 2022 roku już ponad tony meteorytów księżycowych, jakie spadły na Ziemię. Znajdowane były one od początku lat sześćdziesiątych XX wieku, jednak pierwsze ich klasyfikacje jako meteorytów księżycowych wykonane zostały dopiero w 1982 roku. Możliwe to było dzięki bardziej zaawansowanym badaniom geochemicznym i możliwości odniesienia ich wyników do wyników analiz prób skał i regolitu księżycowego przywiezionych przez misje radzieckie programu Łuna, a przede wszystkim przez kilka misji amerykańskich programu Apollo. Dzięki dostępowi na Ziemi do ponad 1,4 tony skał księżycowych możemy obecnie prowadzić multidyscyplinarne badania geologii Księżyca. Ich wyniki są szczególnie ważne w kontekście budowy osiedli ludzkich lub baz na Księżycu w celu dalszej eksploracji Układu Słonecznego. Dotyczy to zarówno właściwości fizycznych tych skał, a także ich składu chemicznego i mineralnego w kontekście występowania złóż różnorodnych surowców mineralnych. Należy podkreślić, że materiału meteorytowego z Księżyca przybywa w ziemskich kolekcjach (zwłaszcza naukowych) bardzo szybko dopiero od roku 2015. Jest to efektem szeroko zakrojonych prac poszukiwawczych przede wszystkim na obszarze Antarktydy, Afryki, Półwyspu Arabskiego i Australii. Wśród zidentyfikowanych skał docierających na Ziemię w postaci meteorytów księżycowych najliczniej reprezentowane są brekcje skaleniowe (impaktowe skały metamorficzne), anortozyty (skały magmowe głębinowe budujące wyżynne obszary Srebrnego Globu) oraz bazalty (skały magmowe wylewne budujące obszary mórz księżycowych). Poza tym spotykane są inne skały magmowe zasadowe, takie jak gabro, noryt, troktolit i inne. Powierzchnię skorupy pokrywa regolit złożony z fragmentów wymienionych skał magmowych i brekcji poddanych rozdrabnianiu kolejnymi zderzeniami z meteorytami i mikrometeorytami oraz działaniu cząstek wiatru słonecznego (wietrzenie kosmiczne). W wyniku tych procesów powierzchnia Księżyca pokryta jest warstwą luźnej skały osadowej okruchowej o miąższości od kilku do kilkunastu metrów. Lokalnie regolit może być skałą osadową okruchową zwięzłą, jeśli znaczna liczba okruchów skalnych ulegnie połączeniu (zespawaniu – ang. welding) szkliwem produkowanym w czasie zderzeń z mikrometeorytami. Autorzy przedstawili także krótko genezę i ewolucję oraz budowę geologiczną Księżyca w oparciu o wyniki najnowszych badań geofizycznych i geochemicznych (w tym izotopowych) oraz mineralogicznych i petrologicznych. Wskazali, że zaproponowany model genezy Księżyca z synestii utworzonej po zderzeniu proto-Ziemi z innym hipotetycznym embrionem planetarnym o nazwie Theia, dobrze tłumaczy jednorodność chemiczną i izotopową Ziemi i Księżyca. Autorzy zwrócili także uwagę, że dzięki wspólnej genezie meteoryty księżycowe klasyfikowane i nazywane są tak samo, jak skały ziemskie, co zdecydowanie odróżnia je od innych meteorytów. Wyjątek stanowią meteoryty marsjańskie oraz HED, które klasyfikowane są podobnie, jak skały ziemskie, aczkolwiek ich nazwy często nie mają odpowiedników w klasyfikacji skał ziemskich (np. meteoryty SNC). Śledząc dane na temat oficjalnie klasyfikowanych meteorytów księżycowych autorzy stwierdzili, że w grudniu 2022 roku łączna masa materii meteorytowej uznanej za pochodzącą z Księżyca przekroczyła 1 tonę. Meteoryty księżycowe są obecnie największym źródłem informacji o geologii Srebrnego Globu, stanowiąc niemal 2/3 masy materii księżycowej dostępnej do badań na Ziemi.
EN
Wlotzka scale (Wlotzka 1993) is commonly used to determine the weathering grade of ordinary chondrites. The scale is descriptive and based mostly on a subjective assessment of researcher. In this paper authors define a new, quantitative method to establish the W0–W4 weathering grade, which is based on planimetry of FeNi grains. Results of planimetry are compared with average content of FeNi metal in unweathered chondrites from the same group. Weathering grade estimated by this method are consistent with, or slightly different from the official one determined in classification, what proves the efficacy of the proposed method. Moreover, the method was applied to define weathering grade of meteoritic samples not classified so far: Pułtusk (W2), Thuathe (W2), Gao-Guenie (W2/W3), NWA 5205 (W3), NWA 4505 (W3), NWA 5296 (W2).
EN
The chemical composition of carbonaceous chondrites was analysed in terms of the content of selected 24 metals, including noble metals and rare-earth metals. Based on the obtained results, the abundance of C-type asteroids in metallic raw materials was estimated and compared to the concentration of terrestrial deposits and the average content in the Earth’s crust. All the analysed elements, except rare earths, showed higher concentrations in carbonaceous chondrites than in the Earth’s crust, but most of them did not match the Earth’s deposit contents. The exception is Fe and Ni, the concentrations of which in carbonaceous chondrites significantly exceed the Earth’s deposit concentrations. The profitability of mining operations on C-type asteroids is also increased by the number of accompanying mineral commodities, mainly metals (Cr, Co, Cu, Au, Pt, Pd, Ag), and water ice. In addition, the parent bodies of carbonaceous chondrites occur relatively close to the moons of Jupiter and Saturn – potential space mission targets.
EN
Based on petrological, mineralogical and geochemical analyses, the authors classified the new meteorite Northwest Africa 11778 as an ordinary chondrite H5, S2, W1. It is a single stone with mass 767.5 g and with well-preserved black fusion crust with brown shade (Fig. 1). This meteorite was found in Sahara Desert and it was purchased by Wroclaw University of Science and Technology, Faculty of Geoengineering, Mining and Geology from Moroccan dealer in Zagora in June 2013. The most characteristic component of analyzed chondrite are different types of chondrules (barred olivine – BO, porphyritic olivine – PO, granular olivine – GO, radial pyroxene – RP, porphyritic olivine-pyroxene – POP, cryptocrystalline – C) (Fig. 2), which constitute 75% of meteorite. Their size is in range 0.2–1.2 mm, with average chondrule size ca. 0.6 mm. Bigger porphyritic olivine chondrules with diameter up to 1.5 mm rarely occur. The chemical composition of olivine crystals (Fa 18 mol%) and pyroxene crystals (Fs 16.2 mol%) proves this meteorite to be an H chondrite (Tab. 1, Fig. 4–5, App. 1–2). The averaged concentration of major elements in the classified meteorite is comparable to their mean content in H chondrites (Fig. 8). The meteorite NWA 11778 contains only slightly less Mg and Al than average H chondrites (Tab. 2). Among the other analysed elements, values distinctly out of the range of typical concentrations for H chondrites are characteristic of Hg and Eu (lower concentration in the NWA 11778 meteorite) (Tab. 3, Fig. 8–9). The presence of chondrules with predominantly sharp boundaries (Fig. 2), secondary feldspar crystals with sizes of up to 50 mm, chiefly crystalline mesostasis and only secondarily – devitrified glass in chondrules, and transparent crystalline matrix (with olivine crystals up to 0.26 mm and pyroxenes up to 0.30 mm in size), as well as common occurrence of untwinned rhombic pyroxenes prove the classified meteorite to belong to petrological type 5. It is additionally confirmed by mean Ni content in troilite below 0.5 wt% (0.04 wt%) (Tab. 1, App. 4) and carbon content below 0.2 wt% (0.07 wt%) (Tab. 2). Undulatory extinction in some olivine and pyroxene crystals and the presence of irregular fractures in the NWA 11778 chondrite enables specifying its shock level as S2. The weathering grade adopted for the NWA 11778 chondrite was W1, as visible weathering changes cover only the marginal parts of FeNi alloy grains. As a result of the weathering of 10–20% of FeNi grains, iron oxides and hydroxides are formed. These secondary weathering Fe3+ compounds also fill cracks, forming veins running between chondrules within matrix (Fig. 3).
EN
Some of M type asteroids, like 016 Psyche, 022 Kalliope, 055 Pandora, 110 Lydia, 250 Bettina, 347 Pariana, 678 Fredegundis, 771 Libera, 872 Holda, are probably the source of iron meteorites. The population of these asteroids is less than 10% of all minor bodies orbiting the Sun in the asteroid belt. In the paper we analyzed the concentrations of 19 selected metals in 1730 iron meteorites according to the groups. Base on it authors found out that beside Fe and Ni the parent bodies of iron meteorites are the richest in Co, Cu, Ge, Cr, and Ga. They are also rich in As, Pt, Mo, Os, Pd, and Ir. The iron meteorites of IVB group are the richest in metals. Meteorites belonging to this group contain the highest average concentrations of Ir, Co, W, Re, Pt, Os, Pd, Rh, Ru, Mo, and Ni. Meteorites from IAB group are the richest in Ge, As, Sb and Au. The parent bodies of iron meteorites, especially from IVB and IAB groups, can be recognized as very rich polymetallic deposits. The concentrations of most of 19 analyzed metals in iron meteorites are greater than the concentrations in Earth’s crust. Only tungsten and chromium according to their strong litophile character occur in lower concentrations than in Earth’s crust. Few of the M type asteroids, those that are the source of iron meteorites, are probably the most differentiated bodies in the asteroid belt. Their chemical composition considerably differs from the composition of CI carbonaceous chondrites. Among their the most differentiated (enriched in some elements and depleted in others) and differing from CI chondrites are the parent bodies of iron meteorites belonging to IVB group. However even they are far less differentiated than Earth’s crust. This is the proof of relatively long chemical evolution of IVB group parent body comparing to parent bodies of other groups of iron meteorites and CI chondrites, but from the other hand the evolution of this body is also significantly shorter than the chemical evolution of Earth’s crust.
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