Meteoritics & Planetary Science 50, Nr 5, 864–879 (2015) doi: 10.1111/maps.12405
Mineralogy, petrography, geochemistry, and classification of the Kosice meteorite 2 CKOV 2, Pavel UHER1, A Daniel OZDIN1*, Jozef PLAVCAN , Michaela HORN A 3,4 2,5 2 4 , Vladimır PORUBCAN , Pavel VEIS , Jozef RAKOVSKY , Juraj TOTH 5 6 Y , and Jan SVOREN Patrik KONECN 1
Department of Mineralogy and Petrology, Faculty of Natural Sciences, Comenius University, Mlynsk a dolina, 842 15 Bratislava, Slovak Republic 2 Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynska dolina, 842 48 Bratislava, Slovak Republic 3 Astronomical Institute of Slovak Academy of Sciences, D ubravsk a cesta 9, 842 28 Bratislava, Slovak Republic 4 Department of Astronomy, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynska dolina, 842 48 Bratislava, Slovak Republic 5 ur, Mlynsk Department of Special Laboratories, State Geological Institute of Dion yz St a dolina 1, 817 04 Bratislava, Slovak Republic 6 Astronomical Institute of Slovak Academy of Sciences, 059 60 Tatransk a Lomnica, Slovak Republic * Corresponding author. E-mail:
[email protected] (Received 05 November 2013; revision accepted 24 October 2014)
Abstract–The Kosice meteorite was observed to fall on 28 February 2010 at 23:25 UT near the city of Kosice in eastern Slovakia and its mineralogy, petrology, and geochemistry are described. The characteristic features of the meteorite fragments are fan-like, mosaic, lamellar, and granular chondrules, which were up to 1.2 mm in diameter. The fusion crust has a black-gray color with a thickness up to 0.6 mm. The matrix of the meteorite is formed mainly by forsterite (Fo80.6); diopside; enstatite (Fs16.7); albite; troilite; Fe-Ni metals such as iron and taenite; and some augite, chlorapatite, merrillite, chromite, and tetrataenite. Plagioclase-like glass was also identified. Relative uniform chemical composition of basic silicates, partially brecciated textures, as well as skeletal taenite crystals into troilite veinlets suggest monomict breccia formed at conditions of rapid cooling. The Kosice meteorite is classified as ordinary chondrite of the H5 type which has been slightly weathered, and only short veinlets of Fe hydroxides are present. The textural relationships indicate an S3 degree of shock metamorphism and W0 weathering grade. Some fragments of the meteorite Kosice are formed by monomict breccia of the petrological type H5. On the basis of REE content, we suggest the Kosice chondrite is probably from the same parent body as H5 chondrite Mor avka from Czech Republic. Electron-microprobe analysis (EMPA) with focused and defocused electron beam, whole-rock analysis (WRA), inductively coupled plasma mass and optical emission spectroscopy (ICP MS, ICP OES), and calibration-free laser induced breakdown spectroscopy (CF-LIBS) were used to characterize the Kosice fragments. The results provide further evidence that whole-rock analysis gives the most accurate analyses, but this method is completely destructive. Two other proposed methods are partially destructive (EMPA) or nondestructive (CF-LIBS), but only major and minor elements can be evaluated due to the significantly lower sample consumption.
© The Meteoritical Society, 2015.
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Mineralogy and geochemistry of the Kosice meteorite
INTRODUCTION On 28 February 2010 at 23:25 UT, a fireball much brighter than the full Moon (P. Seck ar, personal communication) accompanied by a fall of meteorite fragments appeared over Central and Eastern Slovakia. Due to rain and cloudy weather over this area, no optical records from the European Fireball network photographic cameras (Spurn y et al. 2007) or the “Slovak Video Meteor Network” television cameras could be obtained (T oth et al. 2011). However, detailed fireball light curves were detected by radiometers located at seven cameras of the European Fireball Network in the Czech Republic and Austria. The fireball was also accompanied by strong sonic booms recorded by six seismic stations in Slovakia, Hungary, and Poland, and these were observable from a distance of several hundred kilometres. Fortunately, the flight through the atmosphere and fall area near the city of Kosice could be calculated due to two records from surveillance cameras operating in Northern Hungary (Borovicka et al. 2013). The meteoroid flew from west to east over Slovakia and disintegrated in a series of explosions between 57 and 22 km above the Earth’s surface, with meteorite fragments falling northwest of Kosice city. The first fragment weighing 27 g was found near the village of Vysn y Kl atov 20 days after the meteorite fall, and currently 218 fragments with a total weight of 11.3 kg have been recovered from our information (T oth et al. 2015). The two largest recovered pieces are of the weight of 2.38 and 2.17 kg. From a historical viewpoint, the Kosice chondrite is only the sixth meteorite recovered in Slovakia, and it is the first fall observed in 115 yr in the Slovak Republic. The mineralogy, petrography and geochemistry of the Kosice meteorite, based on two fragments, are presented and discussed. The type specimens of this meteorite (fragments no. 20, 58) described and classified in this contribution are located in the mineralogical collection of the Department of Mineralogy and Petrology of the Faculty of Natural Sciences, Comenius University in Bratislava. Other fragments are held at the Department of Astronomy, Physics of the Earth and Meteorology of the Faculty of Mathematics, Physics, and Informatics of the Comenius University, and at the Astronomical Institute of the Slovak Academy of Sciences as well as in the Museum of Natural History of the Slovak National Museum, Bratislava. METHODS The Kosice meteorite was studied by polarized optical microscope, EMPA, ICP MS, ICP OES, Leco combustion analysis, and by the CF-LIBS method.
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There were two fragments that were analyzed, which weighed 22.39 g (No. 20) and 5.64 g (No. 58). The meteorite was first studied using thin sections in polarized and reflected light with the polarized microscope Leica. Electron-microprobe analysis (EMPA) was carried out by the CAMECA SX100 microprobe with wavelength-dispersion spectrometers at the State ur in Bratislava. Geological Institute of Dionyz St Operating conditions were as follows: acceleration voltage of 15 kV, beam current of 20 nA (metallic compounds 20 kV, 20 nA), and beam diameter between 3 and 5 lm. Standards and lines included wollastonite (Si Ka, Ca Ka), TiO2 (Ti Ka), Al2O3 (Al Ka), chromite (Cr Ka), pure Cr (Cr Ka), pure V (V Ka), fayalite (Fe Ka), rhodonite (Mn Ka), MgO (Mg Ka), forsterite (Mg Ka), apatite (P Ka), willemite (Zn Ka), pure Ni (Ni Ka), SrTiO3 (Sr La), barite (Ba La), albite (Na Ka), orthoclase (K Ka), Rb2ZnSi5O12 glass (Rb La), LiF (F Ka), and NaCl (Cl Ka). The following standards were used for elements and sulphidic minerals: CuFeS2 (Cu Ka, Fe Ka, S Ka), PbS (Pb Ma), Ag (Ag La), Cd (Cd La), ZnS (Zn Ka), Bi2Se3 (Bi La), Sb (Sb Lb), HgS (Hg La), InSb (In La), FeAsS (As Kb), and NaCl (Cl Ka). Back-scattered electron images were conducted on the same instrument at an accelerating voltage of 15 or 20 kV with a beam current of 20 nA. Bulk chemical composition of the meteorite was determined at the ACME Analytical Laboratories, Ltd. (Vancouver, Canada). Total abundance of the major oxides was determined by classic whole-rock analysis (Si, Al, Fe, Mg, Ca, Na, K, Ti, P, Mn, Cr) and inductively coupled plasma–emission spectrometry (ICPOES; Sc) following a lithium metaborate/tetraborate fusion and dilute nitric acid digestion. Rare earth (La, Ce, Pr, Nd, Sm, Eu, Gd) and heavy rare earth elements (Tb, Dy, Ho, Er, Tm, Yb, Lu, Y), refractory elements (Mo, Cu, Pb, Zn, Ni, As, Cd, Cb, Bi, Ag, Au, Hg, Tl, Se), and a several other elements (Ba, Be, Co, Cs, Ga, Hf, Nb, Rb, Sn, Sr, Ta, Th, U, V, W, Zr) were determined by ICP mass spectrometry (ICP MS) following lithium metaborate/tetraborate fusion and nitric acid digestion. C and S contents were determined by Leco analysis. The CF-LIBS method is based on focusing of a pulsed laser beam onto the sample, causing ablation of a small part of the sample (tens of ng) and creation of a plasma plume. The resulting ablated material is atomized and ionized into the different excited states. The emission from such plasma gives information about elemental composition of the sample. From the emission of all presented atomic spectral lines, using the procedure described in Ciucci et al.
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(1999), the absolute elemental concentration in the sample can be evaluated. The CF-LIBS approach was studied in detail and focused on the expected accuracy in the work of Tognoni et al. (2007). A critical review of CF-LIBS is provided in the work of Tognoni et al. (2010). Aguilera et al. (2009) applied the CF-LIBS for the radially resolved spectra of copper-based alloys. Acquisition parameters of spectrometer (gate delay and gate width) are crucial for the accurate results. For the elements with high concentration, self-absorption effect often occurs, which causes errors in results. Therefore, the spectral lines affected by this effect must be corrected or rejected from the calculation, see Hor n ackov a et al. (2013). Praher et al. (2010) modified the CF-LIBS approach for the accuracy increasing for the analyses of powder samples. Recently, LIBS and CF-LIBS methods have been applied for the analyses of different geological samples as well as meteorites (e.g., Dell’Aglio et al. 2014). In geosciences, the LIBS method was also used for the two-dimensional multi-elemental mapping of granite samples (Novotn y et al. 2008). The first demonstration of LIBS and CF-LIBS to meteorite analysis and its first comparison with WRA for meteorite samples are reported in well-known papers (Thompson et al. 2006; De Giacomo et al. 2007; Dell’Aglio et al. 2010). For comparison, because CF-LIBS is a potentially new technique for analyzing the meteorites, we analyzed several fragments of the Kosice meteorite by this method. The ablation process was ensured using Q-switched pulsed Nd:YAG laser (Brilliant Eazy, Quantel) operating at the wavelength of 532 nm and with the maximum energy per pulse of 165 mJ. The plasma emission was analyzed by an echelle spectrometer (Mechelle ME 5000, Andor Technology) and recorded using intensified CCD camera (iStar, Andor Technology). Emission spectra were taken as an accumulation of 100 laser pulses from five different spots of the fragments’ surface (total accumulation of 500 laser pulses). To ensure the best experimental conditions, i.e., the best signal-to-noise ratio, the spectrometer was set to start collecting an emission 2.5 ls after the laser pulse and the gate width was set to 0.5 ls. Measurements were carried out at low pressure (6 kPa) in the vacuum chamber evacuated by the vacuum pump in order to minimize spectral line width of observed elements and so to increase the spectral resolution and precision. For comparison with whole-rock and CF-LIBS analyses, we made 24 electron-microprobe analyses UD Bratislava) with extended S, (CAMECA SX100, SG beam at conditions: accelerating voltage of 15 kV, beam current of 40 nA, and diameter of beam 0.05 mm. Besides the above-mentioned standards were used even
Fig. 1. Two types of fusion crust: the central part of the fragment of meteorite is glossy and the external parts are covered by primary fusion crust. Photo Lukas Smula.
following standards and their spectral lines: pure Cr (Cr Ka), pure Co (Co Ka), pure Cu (Cu Ka), barite (S Ka), ZrSiO4 (Zr La), YPO4 (Y La), LaPO4 (La La), CePO4 (Ce La), PrPO4 (Pr Lb), NdPO4 (Nd La), SmPO4 (Sm La), EuPO4 (Eu Lb), GdPO4 (Gd La), YbPO4 (Yb La), ThO2 (Th Ma), and UO2 (U Mb). Twenty-four points were given with automatic step of microprobe across thin section in order to eliminate subjective selection of suitable points for analysis. RESULTS AND DISCUSSION Mineralogy The surface of the Kosice meteorites is black, smooth or rough. Although no regmaglypts are present, no chondrules were macroscopically visible on the surface (Fig 1). The fusion crust is up to 0.6 mm thick. The chondrite contains different types and sizes of chondrules with varied mineral composition. The chondrules have a mosaic, granular, radial, cryptocrystalline, barred, and porphyritic texture (Fig. 2). Maximum chondrule size is up to 1.2 mm, and the most frequent minerals are albite, diopside, enstatite, and forsterite, with chromite and metal-bearing chondrules occasionally observed. Some samples showed brecciated texture in thin section, for example as shown in Fig. 3. Our observations revealed that individual fragments are composed of the same type of chondrite, and
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Fig. 2. Different type of chondrules in the Kosice ordinary chondrite (all BEI). a) Simple albite chondrule with inclusions of chromite; b) a fan-like pyroxene chondrule; c) a mosaic of a slightly differentiated forsterite (gray) and albite (dark gray) chondrule; d) forsterite-diopside lamellar chondrule with interstitial filling of albite.
Fig. 3. Partially brecciated texture of one fragment of the Kosice meteorite. Photo Lukas Smula.
microscopic research showed that fragments had a variable surface, with a characteristic fusion crust mainly composed of remelted albite-like glass (Fig. 4) and nonmelted Fe-Ni metals (Fig. 5). Mineral composition of the Kosice chondrite comprised forsterite (Mg-olivine), enstatite, diopside, augite, albite, chromite, chlorapatite, merrillite, troilite, iron (kamacite), taenite, and tetrataenite.
Fig. 4. Fusion crust composed of plagioclase-glass to albite and chromite. BEI.
Forsterite (Mg2SiO4), an Mg-dominant member of the olivine group, forms a substantial part (approximately 40–45 vol%) of the Kosice meteorite. It is often involved in the groundmass of the chondrite and also in the chondrules (Figs. 6 and 7). The chemical composition of the olivine from the
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Fig. 5. Fusion crust with remelting silicate matrix and nonremelting metals; via transmitted polarized light.
Fig. 7. Olivine (Ol) in the chondrule and chondrite matrix. The essential substance is formed by pyroxenes (Px), albite (Ab), phosphates (Ap—chlorapatite), metals (iron), and troilite (Tro). BEI.
Mg 10
Košice
90
20
80
30
70
forsterite
40
60
50
50
60
40
70
30
fayalite
80
tephroite
20
90
Fig. 6. Irregular olivine (Ol) chondrule with albite (Ab), chromite (Chr), troilite (Tro), iron, merrillite (Mrl), and clinopyroxenes (Cpx). Olivine fissures are filled with a mixture of albite and chromite. BEI.
chondrite matrix and chondrules is the same, and compositional zoning of the grains was not observed. The average composition of the olivine formula is— (Mg1.60Fe2+0.37Mn0.01)1.98Si1.01O4 (n = 62 analyses); and this corresponds to the following average endmember proportions: forsterite 80.7, fayalite 18.8, and tephroite 0.5 mol% (Fig. 8). The contents of Ti, Al, Ni, Ca, Na, and K were very low or under the detection limit of the electron microprobe (Table 1). Pyroxene group minerals form a main component of the meteorite, together with forsterite. The following three members of the pyroxene group were then
10
Fe
Mn 10
20
30
40
50
60
70
80
90
Fig. 8. Triangular diagram of olivine from the Kosice meteorite.
identified: enstatite Mg2Si2O6, diopside CaMgSi2O6, and augite (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 (Table 2, Fig. 9). Enstatite and diopside occur in the groundmass and in chondrules, while augite was found less frequently and only in the meteorite matrix. Pyroxenes in the chondrules associate mainly with forsterite and rarely with albite. The enstatite is chemically homogenous in both studied fragments. Average enstatite composition shows (Mg1.61Fe0.33Mn0.02Al0.01)1.97Si2.00O6 formula, and the content of the ferrosilite (Fe2Si2O6) compound reaches 16.7 mol% (n = 56). The composition of
Mineralogy and geochemistry of the Kosice meteorite
Table 1. The average electron-microprobe analyses of forsterite, albite, chromite, chlorapatite, and merrillite (in wt%).
Wol 10
Forsterite Albite Chromite Chlorapatite Merrillite n 20 SiO2 39.63 TiO2 0.01 P2O5 Al2O3 0.03 Cr2O3 0.03 Fe2O3* V2O3 MgO 42.22 FeO 17.58 MnO 0.47 ZnO 0.07 NiO 0.01 CoO 0.03 CaO Na2O K2 O SO3 H2O* F Cl O=F O=Cl Total 100.09
26 65.45 0.02 20.92
0.41
2.54 9.28 0.99
99.62
17 0.02 2.17 6.76 56.21 2.80 0.69 3.31 25.37 1.00 0.38 0.01 0.04
98.78
8 0.08
11 0.02
42.07
47.16
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Košice 90
20
80
30 40
70
hedenbergite diopside
50
60 50
60
0.27 0.04
40
augite
70
3.65 0.54 0.02
80
20
pigeonite
90
enstatite
En 53.89 0.44 0.03 0.38 0.28 5.02 0.12 1.13 101.23
46.82 2.78 0.06
30
10
20
30
40
10
ferrosilite 50
60
70
80
Fs 90
Fig. 9. Triangular diagram of pyroxene-group minerals from the Kosice meteorite.
101.04
n = number of analyses. Fe2O3*—calculated from the stoichiometric formula.
diopside is also relatively homogeneous, with average formula corresponding to (Ca0.86Na0.04Mg0.92Fe0.11 Mn0.01Al0.02Cr0.02Ti0.01)1.99Si2.00O6 or En48Wo46Fs06 (n = 21; Table 2; Fig. 9). In contrast, augite reveals distinct compositional variations, especially in the Al, Fe, Mg, and Ca contents (Table 2; Fig. 9). However, the average atomic Mg/(Mg+Fe) ratio of all the pyroxene members is similar, measuring 0.83, 0.89, and 0.81 for enstatite, diopside, and augite, respectively. Albite (NaAlSi3O8), a mineral of the feldspar group, is relatively abundant in the Kosice meteorite, and it is mainly associated with chromite, and much less frequently with forsterite, chlorapatite, and merrillite. It occurs in radial chondrules and intergranular spaces. Rarely, albite forms a sheet-like texture with fine-grained inclusions of chromite in the chondrite matrix (Fig. 10) or an impact-melt around the chondrite fragments. Albite is homogenous, with characteristic composition of enriched Ca, up to 2.8 wt% of CaO, and also K, up to 1.2 wt% of K2O) (see Table 1). The average crystallochemical formula of this albite is (Na0.80Ca0.12K0.06Fe0.02)1.00Al1.09Si2.90O8 (n = 24), and it
Fig. 10. Rare albite (dark gray)-chromite (light gray) sheets in silicate-rich chondrite matrix (gray)—evidence of metamorphism in the chondrite. BEI.
is 81.9 mol% albite, 12.4 mol% anorthite, and 5.7 mol% orthoclase (Table 1; Fig. 11). Chromite (Fe2+Cr2O4) forms rare and small subhedral grains up to 0.3 mm. It is usually scattered in intergranular spaces, chondrules, or in grains. Irregular individual granular chromite + albite chondrules, up to 0.35 mm in diameter, were occasionally observed (Fig. 12). The chemical zoning of the chromite grains is very weak, and it is enriched with Mg, Mn, and V (Table 1; Fig. 9). Fe and Cr completely dominate Mg, Al, and other elements in the chromite; atomic
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Table 2. Representative electron-microprobe analyses of pyroxene group minerals (in wt%). Analyses 1–6: diopside (1–3: fan-shaped chondrule, 4–6: chondrite matrix), 7–9: augite, 10–16: enstatite (10–12: fan-shaped chondrule, 13–15: chondrite matrix, 16: enstatite from fusion crust). 5
6
7
SiO2 TiO2 Al2O3 Cr2O3 FeO MnO NiO CoO ZnO MgO CaO Na2O K2 O Total
1 54.48 0.46 0.53 0.77 3.56 0.20 0.00 0.02 0.09 16.85 21.97 0.50 0.00 99.43
54.38 0.46 0.58 0.80 3.57 0.27 0.00 0.02 0.07 16.76 21.55 0.56 0.00 99.04
54.69 0.44 0.57 0.83 4.13 0.24 0.01 0.00 0.11 16.83 21.33 0.55 0.00 99.74
53.85 0.45 0.49 0.80 4.82 0.21 0.07 0.01 0.04 16.64 21.57 0.56 0.01 99.52
54.38 0.48 0.56 0.88 4.06 0.22 0.00 0.00 0.05 16.84 21.40 0.53 0.00 99.41
54.54 0.48 0.54 0.72 3.50 0.25 0.00 0.02 0.06 16.82 22.42 0.51 0.01 99.85
54.34 0.36 0.42 0.47 9.53 0.35 0.09 0.03 0.04 21.34 13.13 0.34 0.01 99.44
51.74 0.44 0.48 0.71 9.21 0.29 0.18 0.00 0.05 17.80 17.26 0.41 0.01 98.61
Fs mol%
10.61
10.67
12.09
13.97
11.90
10.46
20.04
22.49
Fe mol Mg mol Ca mol
4.96 41.81 39.17
4.97 41.60 38.43
5.74 41.77 38.03
6.71 41.29 38.46
5.65 41.79 38.16
4.87 41.72 39.97
13.27 52.96 23.41
12.82 44.17 30.79
10
11
12
13
14
15
16
9
2
3
4
8
SiO2 TiO2 Al2O3 Cr2O3 FeO MnO NiO CoO ZnO MgO CaO Na2O K2 O Total
49.54 0.24 1.67 0.33 9.59 0.31 0.08 0.00 0.10 24.95 11.35 0.72 0.06 98.92
57.21 0.13 0.17 0.14 10.62 0.49 0.00 0.02 0.07 30.71 0.60 0.01 0.00 100.16
56.91 0.11 0.13 0.16 10.58 0.48 0.00 0.02 0.09 30.63 0.76 0.02 0.00 99.90
57.26 0.14 0.14 0.15 10.72 0.42 0.03 0.05 0.11 30.57 0.54 0.00 0.00 100.12
54.60 0.14 0.18 0.10 13.55 0.50 0.40 0.02 0.06 29.82 0.43 0.03 0.01 99.85
56.26 0.17 0.20 0.12 11.39 0.50 0.07 0.01 0.04 30.40 0.51 0.00 0.01 99.69
56.64 0.09 0.09 0.12 11.04 0.47 0.02 0.03 0.08 30.68 0.68 0.02 0.01 99.98
56.87 0.15 0.16 0.11 10.90 0.46 0.01 0.05 0.01 30.97 0.60 0.03 0.00 100.36
Fs mol%
17.73
16.25
16.24
16.44
20.31
17.36
16.80
16.49
Fe mol Mg mol Ca mol
13.34 61.90 20.24
14.79 76.18 1.07
14.73 75.99 1.35
14.92 75.84 0.96
18.86 73.99 0.77
15.85 75.43 0.91
15.37 76.12 1.22
15.17 76.83 1.07
Cr/(Cr+Al) = 0.83–0.86 (0.85 on average), and Fe2+/ (Fe2++Mg) = 0.77–0.85 (0.83 on average) (Table 4, Fig. 13). Small amounts of Ti (0.04–0.07 apfu, 1.5– 2.6 wt% TiO2), V (approximately 0.02 apfu, 0.6–0.8 wt% V2O3) and Zn (approximately 0.01 apfu, 0.3–0.4 wt% ZnO) were detected in the chromite, while Si, Ni, Co, and Ca concentrations are negligible or under the detection limit of the electron microprobe (see Table 4). The calculated Fe3+ content was usually zero, but in some places it was up to 0.03 apfu (0.95 wt% Fe2O3). Meanwhile, the average chromite composition (n = 20)
provides (Fe2+0.84Mg0.17Mn0.03Zn0.01)1.05 (Cr3+1.59Ti0.06 Al0.28V0.02)1.95O4 empirical formula. The temperature of the chromite crystallization was approximately 780 °C, measured by the spinel-olivine geothermometer (Roeder et al. 1979). Chlorapatite (Ca5[PO4]3Cl) is a relatively scarce mineral in the Kosice meteorite, and occurs only in the chondrite matrix. It usually forms individual anhedral grains there, in assemblage with forsterite, pyroxene group minerals, albite, chromite, metals, and troilite. Less frequently, it forms short veinlets, with merrillite/tuite in
Mineralogy and geochemistry of the Kosice meteorite
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FeCr2O4
MgCr2O4
Ab
1.0 10
90
20
0.8
80 70
40
Cr/(Cr+Al)
30
60
50
50
60
Spinel
Hercynite
0.4
0.2
30
80
Chromite
0.6
40
70
Magnesiochromite
20
0.0 90
0.0
10
An
Or 10
20
30
40
50
60
70
80
90
Fig. 11. Chemical composition of albite in triangular feldspar diagram.
Fig. 12. Irregular chromite (light gray) + albite (dark gray) chondrule with iron (white) in chondrite silicate matrix (gray). BEI.
some places in the silicate matrix. Analysis of chlorapatite shows distinct Cl dominancy over (OH) and F, and slightly elevated Na and Fe concentrations (Table 1). (Ca4.85Na0.07Fe2+0.02)4.94 ([P0.99Si0.01]O4)3(Cl0.71,[OH]0.21, F0.08) is the average empirical formula for chlorapatite. Merrillite (Ca9NaMg[PO4]7) is a regular accessory mineral in the Kosice chondrite. It forms 0.08 mm large, anhedral grains irregularly scattered in the meteorite matrix, and also occurs more rarely as small grains in the chondrules. In some places, it occurs in association with chlorapatite. Our analysis indicates elevated Mg and Na contents, corresponding to the
MgAl2O4
0.2
0.4
0.6
Fe2+/(Fe2++Mg)
0.8
1.0
FeAl2O4
Fig. 13. Plot of chemical composition of minerals from the spinel group.
merrillite formula (2.9 to 3.6 wt% MgO and 2.5 to 2.8 wt% Na2O) (Table 1). Troilite (FeS) is an abundant mineral in the Kosice chondrite, but it is less frequent than metals (Fig. 14a). Rarely, troilite occurs as short veinlets with taenite skeletal crystals (Fig. 14b). These textures indicate rapid cooling of the minerals. Crystallo-chemical formulae of troilite vary from Fe1.00S1.00 to Fe1.01S0.99. Other elements play a very minor role in the crystal chemistry of troilite in the Kosice chondrite; an average chemical composition of troilite in wt% is: Fe 63.64, Co 0.11, Ni 0.02, Ge 0.06, Cu 0.02, Si 0.02, Ga 0.01, Cr 0.01, S 36.14, Cl 0.01, and Σ = 100.04. Iron (kamacite) (Fe), taenite c-(Fe,Ni), and tetrataenite (FeNi) are also frequent compounds in the meteorite. Iron is most common, taenite is less frequent, and the tetrataenite is quite unique. Metals are genetically younger than troilite, and often flow around sulfide grains (Figs. 14a, 14b, and 15). Disintegration of solid solution into two phases was observed in one fragment of this meteorite: these phases were sulphidic (troilite) and metallic (iron/taenite) in fragment No. 58 (Fig. 14b). Skeletal crystals of taenite into troilite are evidence of collision of two fragments of meteorite, melting to form of veinlets and rapid cooling during which the minerals formed. The chemical composition of metals in Table 3 is characterized by the strong substitution of Fe↔Ni. A miscibility gap most likely occurs between the taenite and two other metal phases, as shown in Fig. 16a, and NiFe-1 and CuCo-1 substitutions are characteristic for these metals (Figs. 16a and 16b). Fe + Co ↔ Ni + Cu, with an increasing amount of Ni in iron (kamacite), the
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homogeneous composition of forsterite (olivine) and enstatite (low-Ca pyroxene), the presence of secondary albite as crystalline aggregates, and the overall texture which is composed of readily delineated chondrules. Planar fractures in the olivine, together with undulatory extinction of forsterite and albite opaque shock veins and the occasional melt pockets, indicate the S3 stage of shock metamorphism. The weathering grade is W0, due to the negligible oxidation crust and the very short period of 20 days between the meteorite’s fall and the sampling of its fragments. Different analytical methods for determination of chemical composition of fundamental elements were applied (EMPA, WRA, CF-LIBS, EMPA with defocused beam). A reasonable agreement has been obtained with all these methods. The CF-LIBS method can provide fast and almost nondestructive analyses of various fragments of meteorites without a total destruction of analyzed sample because only a small amount (approximately tens of ng) of fragment is consumed during the ablation process. This article provides some of the first analytical data of this method from the meteorites. The brecciated texture as well as S3 stage of shock metamorphism of the Kosice meteorite indicates a series of previous violent collisions in space. The probable origin of the Kosice meteorite orbit is located in the central region of the belt as was dynamically shown in Borovicka et al. (2013). This could explain why the Kosice meteoroid fragmented already at the height of 57 km under the dynamical pressure of only 0.09 MPa. The majority of the mass was released at the height of 39 km under the pressure of about 1 MPa following in a series of later fragmentations (Borovicka et al. 2013). Its dynamical fragmentation behavior resembles other large meteoroids like Tagish Lake—carbonaceous chondrite (Brown et al. 2002) or Almahata Sitta— heterogeneous meteoroid (Borovicka and Charv at 2009; Jenniskens et al. 2009). The Kosice meteorite—ordinary chondrite is homogenous in physical parameters like magnetic susceptibility, bulk, and grain density (Kohout et al. 2014). However, it shares similar weak internal structure as other two meteoroids having similar behavior in the atmosphere and was easily fragmented. The weak structure of the Kosice chondrite is in contrast to some carbonaceous chondrites or brecciated polymict lithologies. On the other hand, some ordinary chondrites like Carancas (Borovicka and Spurn y 2008) have very high strength of about 20–40 MPa, which prevents them from fragmenting in the atmosphere. Acknowledgments—This research was supported by the Slovak Research and Development Agency under
contracts No. APVV-0516-10 and VVCE-0033-07; by VEGA grant No. 1/1157/11 from The Ministry of Education, Science, Research and Sport of the Slovak Republic; and also by Comenius University grants No. UK/428/2013 and UK/537/2013. The authors are grateful to Ł. Smuła, Z. Krisandova, J. Koza, M. Bodnarova, and E. Schunova, finders of the meteorite fragments, which were used in this study and for information to colleague P. Seckar who observed the Kosice fireball live during a business trip home. Editorial Handling—Dr. Pavel Povinec REFERENCES Aguilera J. A., Arag on C., Cristoforetti G., and Tognoni E. 2009. Application of calibration-free laser induced breakdown spectroscopy to radially resolved spectra from a copper-based alloy laser-induced plasma. Spectrochimica Acta B64:685–689. Borovicka J., and Charv at Z. 2009. Meteosat observation of the atmospheric entry of 2008 TC3 over Sudan and the associated dust cloud. Astronomy & Astrophysics 507:1015– 1022. Borovicka J. and Spurn y P. 2008. The Carancas meteorite impact—Encounter with a monolithic meteoroid. Astronomy & Astrophysics 485:L1–L4. Borovicka J., Weber H. W., Jopek T., Jakes P., Brown P. G., ReVelle D. O., Kalenda P., Schultz L., Kucera J., Haloda J., T ycov a P., Fr yda J., and Brandst€ atter F. 2003. The Mor avka meteorite fall. 3. Meteoriod initial size, history, structure, and composition. Meteoritics 38:1005–1021. Borovicka J., T oth J., Igaz A., Spurn y P., Kalenda P., Haloda J., Svore n J., Kornos L., Silber E., Brown P., and Hus arik M. 2013. The Kosice meteorite fall: Atmospheric trajectory, fragmentation, and orbit. Meteoritics & Planetary Science 48:1757–1779. Brearley A. J. and Jones R. H. 1998. Chondritic meteorites. In Planetary materials, edited by Papike J. J. Reviews in Mineralogy and Geochemistry, vol. 36. Washington, D.C.: Mineralogical Society of America. pp. 35–38. Brown P. G., ReVelle D. O., Tagliaferri E., and Hildebrand A. R. 2002. An entry model for the Tagish Lake fireball using seismic, satellite and infrasound records. Meteoritics & Planetary Science 37:661–675. Ciucci A., Corsi M., Palleschi V., Rastelli S., Salvetti A., and Tognoni E. 1999. New procedure for quantitative elemental analysis by laser-induced plasma spectroscopy. Applied Spectroscopy 53:960–964. De Giacomo A., Dell’Aglio M., De Pascale O., Longo S., and Capitelli M. 2007. Laser induced breakdown spectroscopy on meteorites. Spectrochimica Acta B62:1606–1611. Dell’Aglio M., De Giacomo A., Gaudiuso R., De Pascale O., Senesi G. S., and Longo S. 2010. Laser Induced Breakdown Spectroscopy applications to meteorites: Chemical analysis and composition profiles. Geochimica et Cosmochimica Acta 74:7329–7339. Dell’Aglio M., De Giacomo A., Gaudiuso R., De Pascale O., and Longo S. 2014. Laser Induced Breakdown Spectroscopy of meteorites as a probe of the early solar system. Spectrochimica Acta Part B 101:68–75.
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Table 4. Whole-rock composition of the Kosice H5 chondrite. Element
Conc.
Standard. dev.
Unit
Conc/HCa
C Na Mg Al Si P S K Ca Ti Cr Mn Fe Sc V Co Ni Cu Zn Ga As Se Rb Sr Y Zr Nb Mo Ag Cd Sn Cs Ba La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta Au Hg Tl Bi Th U
0.05 0.6 13.8 1.07 16.51 0.12 1.79 0.09 1.14 0.06 0.35 0.23 28.85 8 66 868 >10000 94.4 19 6.3 5.7 6.4 3.2 12.9 1.7 14.7 0.60 1.50
