14 New Data on Minerals. 2014. Vol. 49

NANOCRYSTALS OF NATIVE , AND TITANIUM WITHIN IMPACT GLASSES OF LUNAR REGOLITH Andrey V. Mokhov, Tatyana A. Gornostaeva, Pavel M. Kartashov, Enver E. Asadulin, Oleg A. Bogatikov Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry (IGEM), Russian Academy of Sciences, Moscow, [email protected]

This paper discusses the results of study of the impact glass fragments from the Mare Fecunditatis and Mare Crisium regolith samples brought on the Earth by the Soviet Automatic stations Luna-16 and Luna-24. Nanoinclusions of native molybdenum, iron and titanium were found in the samples with scanning and trans- mission electron microscopy (SEM, TEM). It is shown that these inclusions are single crystals. A natural high pressure native w titanium was identified for the first time. The composition and structure of glass matrix of the regolith samples indicates its extreme micro and nano heterogeneity. The probable formation mechanisms of the studied nanocrystals are discussed. 3 tables, 10 figures, 26 references. Keywords: native molybdenum, native iron, native w titanium, nanophases, single crystals, impact glasses, lunar regolith, Mare Fecunditatis, Mare Crisium.

The main goal of the investigation of mi- Therefore, the aim of this study is investi- ne rals from lunar regolith (average fine lunar gation of structure and formation mecha- matter) was detetermination of the composi- nisms of metal inclusions in lunar glasses. tion and structure of microphases reflecting specific character of mineral-forming proces- Analytical techniques ses at high temperature and pressure gradient in oxygen-free and anhydrous atmosphere. Glass fragments of the regolith samples The impact events determining chemi cal and from the Mare Fecunditatis and Mare physical properties of lunar regolith made a Crisium brought to the Earth by AS Luna-16 substantial contribution to the formation of and Luna-24 were examined with transmis- these phases. However, large grains of native sion (TEM) and scanning (SEM) analytical metals have not been found on the Moon yet. electron mic roscopy using a JEM-2100 These are fine particles up to 150 µm in size microscope equip ped with an IETEM spec- (Frondel, 1975), that predetermined methods trometer INCA-250 and a JSM-5610LV scan- of our study. ning electron microscope equipped with an Particularly, native molybdenum as thin INCA-450 EDS. films and spherical submicron grains was fre- Supporting of purity and prevention of quently found in the Mare Fecunditatis and con tamination by foreign phases has been Mare Crisium regolith samples studying with regarded in the preparation of fine-dispersed SEM (Bogatikov et al., 2001; Mokhov et al., samples of lunar glasses for the SEM analy- 2007; Kartashov et al., 2010). sis. A conductive double-sided tape in whose Iron is the most abundant metal on the com position only carbon and oxygen were Moon; it occurs as oxidized and native spe - detected (within detection limits of EDS) was cies (Frondel, 1975). Irregular-shaped, rib- stuck on ordinary aluminum tables. A tape- bon-like, spherical, and drop-like particles of free surface of the table was coated with gra - native iron are the most abundant in lunar phite glue to avoid a fluorescence of alumi - regolith (Mokhov et al., 2007). num. Immediately after opening, regolith Nonvalent iron, aluminum, silicon and ti - sample was spread as a thin layer on the tanium were identified with the X-ray photo inner side of the tape with removed protec- electron spectroscopy studying condensate tive film and the table with the prepared sam- glass film coating the lunar regolith samples ple was enclosed in clear Petri dish and was from the Mare Fecunditatis (Yakovlev et al., placed in a special storage till the start of 2009). However, these data only indirectly ve - electron mic roscopic study. Thus, a contami- rify me tallic titanium in lunar glass and do not nation of sample by artifacts is eliminated as provide reliable information on its structure. far as possible. Minerals and metals already Nanocrystals of native molybdenum, iron and titanium within impact glasses of lunar regolith 15

Table 1. Compositions of glasses and pyroxene (wt.%) in samples of studied lunar regolith Analysis 12 3* 45678

Na2O 3.9±0.5 2.3±0.4 –––4.2±0.5 1.4±0.4 – MgO 1.3±0.2 2.3±0.2 6.7±0.3 14.8±0.3 4.9±0.3 2.7±0.3 – 6.21±0.3

Al2O3 7.3±0.3 24.5±0.5 18.0±0.4 – 13.0±0.4 22.8±0.5 25.6±0.6 13.6±0.4

SiO2 53.9±0.5 58.1±0.7 43.2±0.6 51.9±0.7 36.7±0.5 54.0±0.8 61.7±0.8 42.4±0.6

K2O––––0.3±0.2 3.7±0.6 –– CaO 5.8±0.2 5.2±0.3 14.6±0.4 8.2±0.3 17.4±0.4 – 11.3±0.4 14.4±0.4

TiO2 0.9±0.1 –––5.6±0.3 ––4.2±0.2 FeO 26.8±0.5 5.1±0.3 17.1±0.5 25.1±0.4 22.1±0.6 12.6±0.5 – 19.1±0.4 BaO – 2.6±0.4 ––––––

Notes: Total is normalized to 100%. *– Contents of Na2O, K2O, and Cl below 0.2 wt.%. Analysts A.V. Mokhov and T.A. Gornostaeva. analyzed were prepared according to the given in Table 1 (an. 1). Secondary and back - procedure of Lapina and Mokhov (1995) for scatte red electron images (Figs. 1a, 1b) clear- using as refe rence samples. ly show a glass coating that eliminates con- A possible contamination of the samples tamination of sample by man-made molyb- with foreign matter is the most dangerous in denum. How ever, because of glass coating, these studies and put in question these fin - the identified inclusions did not show elec- dings. It refers first of all to micro and na - tron backscattered diffraction (EBSD) pat- noparticles, which could easily contaminate terns. These patterns (Fig. 2) supporting me- a sample. We confidently can state that the tallic state of molybdenum grains (Table 2) phases studied are not impurities only if they were obtained only after ion beam cutting of were coated with glass or shallowly sank into the glass coat. it. Fre quently, these phases are sufficiently Nanocrystals of native molybdenum contrasted to be detected because back-scat- (Fig. 3), which occur as chains to form tri- tered electrons are generated and drift out of choid structures (Fig. 4) in glass or as mas- the sample from the relatively great depth. sive segregations also in glass (Fig. 5) were To demonstrate that the particles are coated identified as a result of the TEM study. In the with glass layer an imaging in secondary first case, the microdiffraction patterns show electrons is used because these electrons low intensive discrete-ring reflections of drift out of the sample from quite shallow native molybdenum, whereas in the second depth and allow obtaining information of the case, the micro diffraction patterns are absent morphological features of the sample regard- because of great thickness of the samples. less its mean atomic weight. The composition of glass is close to that Samples were prepared for TEM according determined with SEM (Table 1, an. 1), how- to suspension method of Gritsaenko (1969). ever, the higher content of silica, much lower This method is the most common be cause it concentration of Fe, and small amount of Ba is very informative and simple. A glass frag- were measured (Tab le 1, an. 2). ment nearly hundred microns or larger in Numerous micro- and nanoinclusions of size was placed into clear test mic rotube. native iron were found in the Mare Fe cun - Then, the test tube with a piece of glass in ditatis glass samples with SEM and TEM. few amount of distil analytically pure water Matrix glass containing these inclusions was placed into sonicator for disintegration. inhomogeneous even in scanning electron A sample crushed by ultrasound in water microscope is moreover inhomogeneous in drop was placed on a special cooper grid with transmission electron microscope with the film of formovar and collodion and then was composition significantly different from that dried at 35°С in drying box. de termined with SEM (Table 1, an. 3). Nu - merous fragments of this glass contain both Results spherical nanoparticles and larger irregular- shaped particles. Point TEM analysis showed As a result of the SEM study massive that these larger irregular-shaped microin- spherules of native molybdenum (Fig. 1) we - clusions are different in composition corre- re identified in glass of the Mare Crisium sponding to the rock-forming silicates (pla- rego lith samples with average composition gioclase, pyroxene, olivine), whereas nanoin- 16 New Data on Minerals. 2014. Vol. 49

1a 1b

1c Fig. 1. Native molybdenum coated with film of glass. (a) Secondary electron image, (b) backscattered electron image, (c) energy-dispersive spectrum.

0

2a 2b 2c

2d Fig. 2. A particle of native molybdenum. (a) After ion beam etching; (b) analyzed point; (c) electron backscattered diffraction patterns; (d) energy-dispersive spectrum (contains glass elements peaks induced by fluorescence).

clusions are enriched only in Fe in compari- ments containing the largest inclusions of son with glass. this type were obtained to determine the Figure 6 shows the glass fragment contai - exact composition of these globules. The pat- ning large irregular-shaped inclusion whose terns obtained verified an absence of oxygen composition given in Table 1 (an. 4) corre- and appreciable contents of other elements

sponds to pigeonite (Mg0.85Fe0.81Ca0.34)2(Si2O6), than iron in glo bules. The microdiffraction In addition, many spherical nanoinclusions pattern registered for such globule contained are shown in Fig. 6. The elemental distribu- weak reflections 110 of cubic native a iron tion patterns within one of the glass frag- with a of 0.28 nm and space group Im 3m. Nanocrystals of native molybdenum, iron and titanium within impact glasses of lunar regolith 17

High resolution imaging revealed a periodi - Table 2. Result of automatic identification of phase city of structure with step of 0.2 nm that cor- according to the EBSD data based on responds to d-spacing characteristic of this Inorganic Database type reflections (Fig. 7). Name Mo The irregular-shaped inclusions of native Symmetry Cubic titanium (Fig. 8a) of a few to a few tens na no- Laue class 11 meters in size were found in a glass fragment Space group Im 3m (229) similar to titanaugite in composition (Table 1, Unit cell an. 5). The microdiffraction patterns con- a 3.15 Å firmed that native titanium is high-pressure b 3.15 Å hexagonal w modification with a 0.462 nm c 3.15 Å and space group P6/mmm. Fig. 8b shows the a 90.00° microdiffraction pattern of this phase in b 90.00° plane (001). The diffraction modeling of the g 90.00° structure of the native titanium w modi fi - cation using the eMap software package sup- samples are remarkably variable in composi- ported the identity of model obtained and tions as it follows from the high resolution microdiffraction pattern. measurements. It is the most pronounced in High resolution imaging has identified TEM with resolution of 5 to 10 nm. Glasses hk0 type planes of native titanium with 2D close in composition to silicate phases are picture with d-spacing 0.23 nm correspon- frequent. For example, the glass fragments ding to 11.0 reflections being recorded in one with the compositions satisfactorily recalcu- case. In the other cases, only 1D structure has lated on formulas of sodium feldspar, olivine been displayed because of inexact match of and pyroxenes were found. Also a few frag- structural planes with transmitting electron ments of Si-rich glasses containing only beam. 2–7 wt.% Al2O3 in addition to SiO2. Hete - It should be noted that glass fragments in rogeneity of glasses was presented even at the Mare Fecunditatis and Mare Crisium nanoscale level.

34Fig. 3. Trans mis - sion elec tron mic ros copy ima - ge of native mo - ly bdenum nano - crystal in glass.

Fig. 4. Trans mis - sion elec tron mic roscopy ima - ge of native mo - lybdenum coa - ted with glass layer.

5 6 Fig. 5. Trans mis - sion electron mic roscopy ima - ge of aggregate of native molyb- denum coated with glass layer.

Fig. 6. Trans mis - sion electron mic roscopy ima - ge of glass of the AS “Luna-16” regolith with inclusions of iron spherules and pyroxene. 18 New Data on Minerals. 2014. Vol. 49

7 8a

8b 8c Fig. 7. Transmission electron microscopy image of single crystal spherules of native iron.

Fig. 8. Single crystal grains of native w Ti in pyrox- ene glass. (a) Transmission electron microscopy image of separate nanocrystal of native w Ti; (b) its microdiffraction pattern; (c) model developed in eMap.

For example the structure of pyroxene Discussion composition glass is heterogeneous in size and distribution of structural clusters. The It should be noted that native molybde- fragment of glass tough and homogeneous in num has been previously found with SEM by the core is characterized by larger disordered Bogatikov et al. (2001) and Kartashov et al. clusters in the rim. The composition of this (2010), but no any structure characteristics external unconsolidated glass film (Table 1, were obtained. Currently, as a result of the an. 6) substantially differs from that of matrix EBSD and TEM study, not only native state of (Table 1, an. 5). molybdenum was confirmed, but its forma- Thin glass layer of 5 to 30 nm thick differ- tion as aggregates of nano-sized single cryst- ent in composition from matrix is frequently sls was established. In other words, the dis- observed on the TEM images. It coats as hard- tinction of lunar molybdenum crystallized in ly distinguishable layer both mineral phases the cubic system from hexamolybdenum of different composition and other glasses. phase discovered in C chondrites (Ma et al., Native molybdenum in such glass is shown in 2009) not only in composition, but in struc- Fig. 4 and a thin glass layer of other ture was confirmed. Native molybdenum was (Table 1, an. 7) coating massive glass (Tab - found on the Earth as an inclusion in carbo - le 1, an. 8) similar to that shown in Fig. 8a is nado (Silaev et al., 2004) although no struc- seen in Fig. 9. tural data were given. Coating glasses are variable in composi- As a result of previous TEM study of lunar tion that differs from that of matrix both glasses, nanoinclusions of iron ranging from quantitative and quailitative. In particular, a few to a few hundreds nm in size were barium traces were measured in glass coating found (James et al., 2002). These iron-bear- native molybdenum and small sodium peaks ing inclusions were interpreted as native were recorded in glass coating native iron iron, but reliable evidences about presence and titanium. of these particles as metallic species were not Of special note are high resolution reported. We did not find any information on images of glass coating native iron, molybde- the crystallinity degree of these grains (Kel - num and titanium demonstrating single crys- ler, McKay, 1993; Thompson, Christof fer sen, tal and nano-sized character of their grains. 2010). How ever, now we have established Nanocrystals of native molybdenum, iron and titanium within impact glasses of lunar regolith 19 monocrystal line character of these nano - 9 grains. Nonvalent titanium has been identified in glasses of the Moon studied with X-ray pho- toelectronic spectroscopy (Dickov et al., 1977; Yakovlev et al., 2009). Native titanium was found on the Earth many times. For the first ti me it was mentioned by Trunilina et al. (1988), who reported the millimeter-size la- mellae of native titanium in crushed leuco - granite samp les from the Bezhy myannyi Pluton in the northeastern Yakutia. Then titanium as micrograins in association with other native metals, carbides and carbons was found in fumarole exhalations of The Great Tolbachik Fissure Eruption occurred Fig. 9. Transmission electron microscopy image of glass coated in 1975 (Glavatskikh and Gorshkov, 1992). In with thin layer of another glass. the last case, its structural parameters were determined with electron microdiffraction. microseconds at impact. Apparently, the This proved an existence of titanium as sample studied was not an nealed after being a species and polycrystalline na tu re of found formed and quenched and it was preserved in aggregate. The resolution of used transmis- initial state in glass to recent time. sion electron microscope was insufficient for In general, the data obtained indicate a determination of size and shape of single significant heterogeneity of low-Si matrix crystals in these aggregates. glasses. Frikh-Khar et al. (1988) were the first Finally, native titanium was approved as who noticed heterogeneity of lunar glasses at mineral species on material from the Luo bu - submicron level studying with scanning elec- sha chromite massif in Tibet (Fang et al., tron microscope. The compositional hetero- 2013), where it is associated with native me- geneity of glasses from regolith samples col- tals, intermetallic compounds, alloys, dia- lected in area of AS Luna-16 landing have monds, and various carbides and silicides. been earlier detected by Dikov et al. (1998, As sociations and direct intergrowths of tita- 2002) using layer by layer analysis performed nium with the high-pressure phases allowed with X-ray photoelectron spectroscopy. As a estimating pressure range of 2.8 to 4 GPa result, variable compositions both between under which it can be formed. Nevertheless, layers and within individual layer in lateral a common low-pressure a titanium with direction were established. The Na-rich na-

P63/mmc space group was found there (Fang no-size coarse-cluster layer of glass could be et al., 2013). explained by vapor condensation out of im - We identified natural high-pressure w ti - pact cloud. The fragments of more refractory ta nium polymorph with P6/mmс space group high-Si glass consolidating before low-Si for the first time. According to Jamieson glass are emplaced into liquid low-Si matrix (1963), a titanium transits to w species at 6 GPa. Table 3. Minimum value (min), median (Me), arith- metical mean (m), maximum value (max) of How do we explain the presence a tita - component contents in glasses nium the high-pressure mantle assemblage in Tibet? The answer is found in the same Components, wt.% min Мe m max n* paper by Jamieson (1963). Annealing of SiO2 30.71 54.39 63.84 97.67 78 w titanium at 110°С for 17 h causes transition TiO2 0.05 0.68 0.84 5.86 34 of w to a mo dification. Obviously, initially Al O 0.96 4.50 8.88 34.08 77 high pressure w titanium transited to a mo - 2 3 FeO 0.06 13.37 12.81 35.35 55 dification as a result of retrograde metamor- phism of host chromitite in the upper crust. MgO 0.05 5.39 6.63 32.40 61 At the same ti me, lunar w titanium resulted CaO 0.15 6.45 7.14 25.83 73 from high-energy impact event (possibly Na2O 0.09 1.62 3.78 25.41 55 during the formation of diaplectic glass after K2O 0.13 0.49 1.53 8.27 42 titanaugite crystal) was quickly quenched Notes: * – 78 observations in total, n – denotes number of owing to rapidity of an impact process. In- observations with the component content higher above detec- deed, colossal PT values exists only during tion limit. 20 New Data on Minerals. 2014. Vol. 49

10 Fig. 10. His - tograms of

SiO2 and FeO contents ob - tained study - ing lunar re - go lith glasses with high re - solution. flequency flequency

wt.% wt.% as so lids. Microfragments of diaplectic glass- terial. Histograms de monstrate this vividly. es are also emplaced in it. In addition, For example, Fig. 10 shows histograms of nanoparticles of some mineral (crystalline) SiO2 and FeO contents which exceed 60% of phases were em placed into studied low-Si in the chemical composition of the glasses glass. Thus, a few versions regard to the ori - examined. Multimodal distribution of these gin of native iron in clusions in glass are sug- constituents indicates quite obviously hete - gested. Two mechanisms are believed to be rogeneity of the material stu died. major. Of special note is the isolating role of According to the first, the drops of native glass or more likely condensate film coating iron resulted from impact and immediately nearly all mineral microparticles with nano- crystallized were emplaced into liquid glass. size layer in the studied regolith samples and This mechanism is supported by the pres- preven ting native phases from oxidation and ence of large pyroxene single crystal proba- interaction with other phases. bly raised up from the surface as a result of explosion and trapped by the glass. Appa - Conclusions rently, this mechanism explains the presence of molybdenum nanocrystalls and other min- 1. Aforementioned native metals are eral phases in glass (Mokhov et al., 2007; nanocrystals or aggregates of nanocrystals Kartashov et al., 2010; Mokhov et al., 2011; implying short period of crystallization. This Gornostaeva et al., 2012). corresponds conditions of impact events on According to the second mechanism that the Moon. is very popular among researchers, Fe0 is re - 2. The presence of glasses dramatically sulted from impact melting and reduction of different in composition, physical properties silicate Fe2+ as affected hydrogen implanted (particularly in melt temperature and fugaci- by solar wind (Housley et al., 1973; Wang et ty of constituents), and structure of their ag- al., 2012). gregates in the same regolith particle allows Massive (exceeding a few unit cells in to assume significant difference in the energy volume) particles of native iron are thought range of impact events, which caused their to be unlikely resulted from disproportionate formation. In other words, regolith samples reaction in impact cloud (Yakovlev et al., studied are a product of multiple impacts 2009). with different energy, i.e. with different mas - The data of high-resolution elemental ses and velocities of impactors. ana lysis obtained with SEM and TEM were 3. Both native metals and many other mi - pro cessed to estimate a degree of homogene- neral phases in the samples studied are usu- ity of glass. Only values higher than detec- ally coated with thin sometimes nano-thick tion limits were taken into account; there- condensate films of glass. It supports an fore, numbers of element measurements are authenticity of these inclusions and explains different. Re sults are given in Table 3 as fol- the inoxidability of lunar native iron (proba- lows: minimum value, median, arithmetical bly also other minerals) in the Earth environ- mean (AM), maximum value, and number of ment conditions that is alternative to expla- observations. Dispersion between minimum nation of inoxidability caused by long bom- and maximum con centration along with dif- bardment by protons of solar wind (Vi - ferences in median values and arithmetical nogradov et al., 1972; Vinogradov et al., means indicate heterogeneity of the ma - 1979). Nanocrystals of native molybdenum, iron and titanium within impact glasses of lunar regolith 21

Acknowledgements Fourth Lunar Sci. Conf. Suppl. No 4. Geo- chim. et Cosmochm. Acta. 1973. Vol. 3. This study was supported by the Russian P. 2737–2749. Foundation for Basic Research (project no. James C., Letsinger S., Basu A., Wentworth S.J., 12-05-00624a). McKay D.S. Size distribution of Fe0 globules in lunar agglutinitic glass // 33nd Lunar and References Planetary Sci. Conf. Houston, Texas. 2002. Bogatikov O.A., Gorshkov A.I., Mokhov A.V., (abstract #1827). CD ROM. Ashikhmina N.A., Magazina L.O. The first Jamieson J.C. Crystal structures of titanium, finding of native molybdenum, silver sul- zirconium and hafnium at high pressures phide and iron-tin in the lunar regolith // Science. 1963. Vol. 140. No. 3562. // Geochem. Int. 2001. Vol. 39. No. 6. P. 72–73. P. 604–608. Kartashov P.M., Mokhov A.V., Gornostaeva T.A., Dikov Yu.P., Nemoshkalenko V.V. Aleshin V.G. Bogatikov O.A., Ashikhmina N.A. Mineral Bogatikov O.A., Ivanov A.V. Reduce titani- phases on the of a glass particle um in lunar regolith // Dokl. Acad. Nauk and in the fines of a Luna 24 regolith sample SSSR. 1977. Vol. 234. No. 1. P. 176–179 (in // Petrology. 2010. Vol. 18. No. 2. Russian). P. 107–125. Dikov Yu.P., Ivanov A.V., Wlotzka F., Gali mov E.M., Keller L.P., McKay D.S. Discovery of vapor de - Wanke G. High enrichment of carbon and posits in the lunar regolith // Science. 1993. volatile elements in the surface layers of Vol. 261. P. 1305–1307. Lunar 16 soil sample 1635: results of comet or Lapina M.I., Mokhov A.V. Technique of refe - meteorite impact? // Earth Planet. Sci. Lett. rence samples preparation for transmission, 1998. Vol. 155. P. 197–204. scanning electron microscopy and micro- Dikov Yu.P., Ivanov A.V., Wlotzka F., Ga - probe analysis // Bull. Russian Acad. Sci., limov E.M., Wanke G. The nature of vo - Ser. Physics. 1995. Vol. 59. No. 2. P. 38–41 latiles in the lunar regolith // Solar System (in Russian). Research. January 2002. Vol. 36. Issue 1. Ma C., Beckett J.R., Rossman G.R. and P. 1–11. hexamolybdenum: two new ultra refractory Fang Q., Bai W., Yang J., Rong H., Shi N., Li G., minerals in Allende and two missing links // Xiong M., Ma Z. Titanium, Ti, a new mi - 40th Lunar and Planetary Sci. Conf. Houston, neral spe cies from Luobusha, Tibet, China Texas. 2009. P. 1402–1403. // Acta Geol. Sinica. 2013. Vol. 87. No. 5. Mokhov A.V., Kartashov P.M., Bogatikov O.A. P. 1275–1280. New data on mineralogy of the Moon (the Frikh Khar D.I., Boyarskaya R.V., Volkova V.M., Mo on under microscope) // Ed. Bortni - Kostin K.B., Mokhov A.V. Inhomogeneity in kov N.S. Moscow: Nauka. 2007. 128 p. (in natural glasses // Int. Geol. Rev. 1988. Russian). Vol. 30. No. 4. Р. 422–429. Mokhov A.V., Kartashov P.M., Gornostaeva T.A., Frondel J.W. Lunar Mineralogy. New York: Bogatikov O.A. Native ytterbium of AS Luna- Wiley Interscience. 1975. 332 p. 24 regolith // Dokl. Earth. Sci. 2011. Vol. 441. Glavatskih S.F., Gorshkov A.I. Natural analog of No. 2. P. 1692–1694. a titanium in exhalations of The Great Silaev V.I., Petrovsky V.A., Sukharev A.E., Mar - Tolbachik Fissure Eruption (Kamchatka) // tins M. Carbonado: a brief review of exami- Dokl. Acad. Nauk. 1992. Vol. 327. No. 1. nation // Bull. Inst. Geol. Komi Sci. Center, P. 126–130 (in Russian). Urall Branch, Russian Academy of Sciences. Gornostaeva T.A., Kartashov P.M., Mokhov A.V., 2004. No. 11. P. 7–13 (in Russian). Bogatikov O.A. Native rhodium-bearing fer- Thompson M., Christoffersen R. The smallest lu - roplatinum in a lunar regolith sample from nar grains: analytical tem characterization of the Mare Fecunditatis // Dokl. Earth Sci. the sub micron size fraction of a mare soil // 2012. Vol. 444. No. 2. P. 770–772. 41st Lunar and Planetary Sci. Conf. Ho uston, Gritsaenko G.S., Zvyagin B.B., Boyarskaya R.V., Texas. 2010. P. 2191. Gorshkov A.I, Samotoin N.D., Frolova K.E. Trunilina V.A., Roev S.P., Makhotko V.F., Zaya - Methods of electron microscopy of mine- kina N.B. Native titanium in granitiods of the rals. Moscow: Nauka. 1969. 311 p. (in Bezymyany Pluton, East Yakutia // Dokl. Russian). Acad. Nauk SSSR. 1988. Vol. 303. No. 4. Housley R.M., Grant R.W., Paton N.E. Origin and P. 948–951 (in Russian). characteristics of excess Fe metal in lunar Vinogradov A.P., Barsukov V.L., Urusov V.S., glass welded aggregates // Proc. of the Bo gatikov O.A. Unoxidability feature of 22 New Data on Minerals. 2014. Vol. 49

ultradisperse species of elements existing Wang K., Moynier F., Podosek F.A., Foriel J. An on the surface of space bodies // Find cer- iron isotope perspective on the origin of the tificate No 279 registered in National find nanophase metallic iron in lunar regolith // registry of the USSR November, 15. 1979 (in Earth Planetary Sci. Lett. 2012. Vol. 337–338. Russian). P. 17–24. Vinogradov A.P., Nefedov V.I., Urusov V.S., Yakovlev O.I., Dikov Yu.P., Gerasimov M.B. Zha voronkov N.M. X-ray photoelectron stu- Effect of the disproportionation reaction of dy of metallic iron in lunar regolith // Dokl. ferrous iron in impact-evaporation proces - Acad. Nauk SSSR. 1972. Vol. 207. No. 4. ses // Geochem. Int. 2009. Vol. 47. No. 2. P. 433–436 (in Russian). P. 134–142.