Morphology and Physico-Chemical Characteristics of an Iron Fragment from Chaco Province

Total Page:16

File Type:pdf, Size:1020Kb

Morphology and Physico-Chemical Characteristics of an Iron Fragment from Chaco Province MORPHOLOGY AND PHYSICO-CHEMICAL CHARACTERISTICS OF AN IRON FRAGMENT FROM CHACO PROVINCE I.A. BUCURICA1,2, C. RADULESCU1,3*, A.A. POINESCU4*, I.V. POPESCU1,3,5, I.D. DULAMA1, C.M. NICOLESCU1, S. TEODORESCU1, M. BUMBAC3, G. PEHOIU6*, O. MURARESCU6 1 Valahia University of Targoviste, Institute of Multidisciplinary Research for Science and Technology, 130004 Targoviste, Romania; E-mail: [email protected] 2 University of Bucharest, Faculty of Physics, Doctoral School of Physics, 050107 Bucharest, Romania 3 Valahia University of Targoviste, Faculty of Sciences and Arts, 130004 Targoviste, Romania; E-mail: [email protected] 4 Valahia University of Targoviste, Faculty of Materials Engineering and Mechanics, 130004 Targoviste, Romania; E-mail: [email protected] 5 Academy of Romanian Scientists, 050094 Bucharest, Romania; E-mail: [email protected] 6 Valahia University of Targoviste, Faculty of Humanities, 130105 Targoviste, Romania; E-mail: [email protected] *Corresponding authors: [email protected]; [email protected]; [email protected] Received October 17, 2018 Abstract. This study aims to demonstrate that the investigated sample is nickel- rich, a signature of the meteorites composed of iron, in order to establish if studied sample belongs or not to Campo del Cielo meteorite group. The discrete structure found in meteorites is a fingerprint fully justified by structural analysis using optical microscopy (OM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), as well as by elemental content using energy dispersive spectrometry (EDS) and inductive coupled plasma mass spectrometry (ICP-MS). The presence of crystalline phase’s kamacite and taenite was confirmed, with a good correlation between experimental results and standard diffraction data (i.e. ICDD card numbers of minerals). Vickers hardness tests (HV 0.1 and HV 1.0) were achieved in accordance with STAS 492/1-85 and the average values (247–255.2 N/mm2) include the fragment into iron meteorite hardness category. The isotopic signature of kamacite (δ56/54Fe = 0.15‰ and δ62/60Ni = 0.81‰) determined by ICP-MS, certify the origin of metallic fragment in Campo del Cielo meteoritic group. Key words: iron-nickel meteorite, optical microscopy, SEM-EDS, XRD, Vickers hardness, ICP-MS, isotope ratio. 1. INTRODUCTION Not once, the objects discovered near the meteorites craters, wrongly been considered fragments of meteorites. For that, many scientists from all over the world are contribute to reveal the authenticity of the outer space matter, found on Earth’s surface. As known, the meteorite is the last stage of a meteoroid transformation Romanian Journal of Physics 64, 906 (2019) Article no. 906 I.A. Bucurica et al. 2 on its way to Earth. The meteoroid originates from the decomposition of asteroids / comets, as a result of which fragments of them enter the atmosphere of the Earth and, more often than not, they break down by burning. Passing through the atmosphere of the Earth leads to the appearance of a luminous effect called a meteor / shooting star. The meteoroid falled on Earth is called the meteorite. If meteoroids are large enough, the heating effects affect only the external portion, leaving the interior unaffected [1]. Meteorites can be classified into three main groups: irons (hardness 4–5 Mohs scale), stones (hardness 6 Mohs scale) and mixed meteorites (hardness 6–7 Mohs scale). From the mineralogical point of view, meteorites consist of different amounts of iron-nickel alloys, silicates, sulphides and other phases in small quantities [2]. Considering Wasson and Kallemeyn [3] evaluations, all the irons meteorites that contain graphite and carbides are member of IAB group complex, these irons commonly contain silicates, like those in group IIE, and were not formed by fractional crystallization in metalic cores of asteroids, but in localized metallic pools by processes that are still poorly understood [4, 5]. Depending on the percentage of nickel in iron, these subdivisions are classified into: hexahedrites (< 6% Ni), octaedrites (6%–17% Ni) and ataxites (> 17% Ni). Octaedrites are the most common type of iron meteorite showing unique structure, called the Widmanstatten structure. This unique structure is the result of the combination of kamacite and taenite present in approximately equal amounts [6]. Obviously, the recognizing of meteorite is not easy at all, many of them being quite often confused with terrestrial rocks. As a distinctive sign for most of the meteorites is the melting crust. It usually has a dark or dark gray color, differing from the shading surfaces, colored lighter (usually gray), also, in the structure of the crust can be observed mainly the traces of the action of atmospheric currents. But there are meteorites where crust is transparent or rusty. In this study a metallic object, supposed to be a meteorite fragment from New Campo del Cielo group (Argentina), was investigated from the physico-chemical point of view. By deduction, this fragment was marked as possible part of the iron- based meteor group, discovered in the provinces of Chaco and Santiago del Estero since 1576. The Campo del Cielo meteorites are considered to be a silicate-bearing iron type which has been classified as belonging to the IAB Main Group [3]. Most of the Campo del Cielo samples are dominantly FeNi metal (bulk composition 6.68% Ni), and approximately 10% are silicate-rich [7]. These silicate-rich samples are mainly characterized by silicate clasts contained within metal, and a small proportion is dominated by silicate material with networks of metal veins. The silicate material in these samples is C- and S-enriched [7]. In the meteorological catalog of the Natural History Museum in London (UK), these discovered fragments are classified as belonging to coarse octaedrites category [3, 8, 9]. In this respect, several complementary techniques have been used and the obtained results were compared with the scientific literature [10–16], but also with the catalogs of the International Society for Meteorics and Planetary Science [9]. 3 Iron fragment from Chaco Province Article no. 906 2. MATERIALS AND METHODS 2.1. MATERIALS AND SAMPLE PREPARATION The dark-grey solid fragment presented in Figure 1 have a weight of 7.3 g and a melted non-uniform structure and is supposed to be some kind of out of space object. This item has no authenticity certificate and was received from an anonymous collector. From the owner testimonial it is know the fact that originates from South America, more precisely, near Chaco province in Argentina. Fig. 1 – Metallic object suppose to be a meteorit fragment from New Campo del Cielo group (Argentina). All chemical reagents were of analytical grade. Distilled deionized water (Milli-Q Water System Millipore), hydrochloric acid (37%, Merck) and nitric acid (high purity, Merck) were used for digestion process, as well for blank preparation. For hardness tests, Optical Microscopy (OM) and Scanning Electron Microscopy coupled with Energy Dispersive Spectrometry (SEM-EDS), the sample was polished with sand paper (different granulometry) and diamond paste, and etched with 2% Nital solution (2% nitric acid in methanol). In the end, the sample was cleaned with distilled ionized water and dry with high pressure nitrogen flux (2 atm). For the XRD analysis, a piece weighing 2.06 g, overall dimensions of 14 × 11 × 3 mm, and having two distinct sides was provided. Visual examination showed a metallic appearance, without sandy or stony insertions. One side had a specific cut and treatment of an optical investigation that was previously performed, to search for corresponding characteristics such as Widmanstätten pattern etc. The second side had no treatment. This untreated side was considered to belong to the outer side of the parent meteorite body, when this was reaching the atmosphere and broke into pieces. For ICP-MS analysis, the sample (i.e. 50 mg) was digested with 3 mL HNO3 and 9 mL HCl on a hot plate by using a TOPwave Microwave-assisted pressure system (Analytik Jena). After digestion process, the PTFE-TFM vessel with sample was cooled for one hour, and then the solution was transferred with distilled water to 100 mL volumetric flasks. Finally, the clear solution sample was analyzed by Article no. 906 I.A. Bucurica et al. 4 ICP-MS. For this stage, ultra-pure argon (99.999% pure) was used as cooling, auxiliary, and nebulizer gas. 2.2. CALIBRATION STANDARDS Solutions for quantitative measurements were prepared using Certipur® Certified Reference Material ICP multi-element standard IV (~1000 mg/L in 6.5% HNO3, Merck) in 5% HNO3 without further purification. The standard multielement solution contain: Ag (1011 mg/L), Al (999 mg/L), B (990 mg/L), Ba (1009 mg/L), Bi (1000 mg/L), Ca (995 mg/L), Cd (999 mg/L), Co (998 mg/L), Cr (999 mg/L), Cu (998 mg/L), Fe (999 mg/L), Ga (997 mg/L), In (998 mg/L), K (1003 mg/L), Li (999 mg/L), Mg (1001 mg/L), Mn (1001 mg/L), Na (1003 mg/L), Ni (999 mg/L), Pb (1001 mg/L), Sr (998 mg/L), Tl (1002 mg/L), and Zn (999 mg/L). 2.3. ANALYTICAL TECHNIQUES Optical Microscopy Stemi 2000-C and Axio Imager M2m microscopes by Zeiss’s were used for optical investigations due to different approach of the study. On first stage, the stereo microscope Stemi 2000-C, designated for high volume samples that require variable working distance was used at 40x magnification range. Also, this microscope, through its attached Axiocam 105 digital video camera (5 megapixel HD), allowed real-time image acquisition. After preliminary information were obtained, Axio Imager M2m and its capabilities was considered to be more suited for reaching even closer to the surface, so, by using AxioCam ICc5 and 50x EC Epiplan-NEOFLUAR objective, were performed new series of optical analysis for more accurate surface images.
Recommended publications
  • Handbook of Iron Meteorites, Volume 3
    Sierra Blanca - Sierra Gorda 1119 ing that created an incipient recrystallization and a few COLLECTIONS other anomalous features in Sierra Blanca. Washington (17 .3 kg), Ferry Building, San Francisco (about 7 kg), Chicago (550 g), New York (315 g), Ann Arbor (165 g). The original mass evidently weighed at least Sierra Gorda, Antofagasta, Chile 26 kg. 22°54's, 69°21 'w Hexahedrite, H. Single crystal larger than 14 em. Decorated Neu­ DESCRIPTION mann bands. HV 205± 15. According to Roy S. Clarke (personal communication) Group IIA . 5.48% Ni, 0.5 3% Co, 0.23% P, 61 ppm Ga, 170 ppm Ge, the main mass now weighs 16.3 kg and measures 22 x 15 x 43 ppm Ir. 13 em. A large end piece of 7 kg and several slices have been removed, leaving a cut surface of 17 x 10 em. The mass has HISTORY a relatively smooth domed surface (22 x 15 em) overlying a A mass was found at the coordinates given above, on concave surface with irregular depressions, from a few em the railway between Calama and Antofagasta, close to to 8 em in length. There is a series of what appears to be Sierra Gorda, the location of a silver mine (E.P. Henderson chisel marks around the center of the domed surface over 1939; as quoted by Hey 1966: 448). Henderson (1941a) an area of 6 x 7 em. Other small areas on the edges of the gave slightly different coordinates and an analysis; but since specimen could also be the result of hammering; but the he assumed Sierra Gorda to be just another of the North damage is only superficial, and artificial reheating has not Chilean hexahedrites, no further description was given.
    [Show full text]
  • Nanomagnetic Properties of the Meteorite Cloudy Zone
    Nanomagnetic properties of the meteorite cloudy zone Joshua F. Einslea,b,1, Alexander S. Eggemanc, Ben H. Martineaub, Zineb Saghid, Sean M. Collinsb, Roberts Blukisa, Paul A. J. Bagote, Paul A. Midgleyb, and Richard J. Harrisona aDepartment of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, United Kingdom; bDepartment of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, United Kingdom; cSchool of Materials, University of Manchester, Manchester, M13 9PL, United Kingdom; dCommissariat a` l’Energie Atomique et aux Energies Alternatives, Laboratoire d’electronique´ des Technologies de l’Information, MINATEC Campus, Grenoble, F-38054, France; and eDepartment of Materials, University of Oxford, Oxford, OX1 3PH, United Kingdom Edited by Lisa Tauxe, University of California, San Diego, La Jolla, CA, and approved October 3, 2018 (received for review June 1, 2018) Meteorites contain a record of their thermal and magnetic history, field, it has been proposed that the cloudy zone preserves a written in the intergrowths of iron-rich and nickel-rich phases record of the field’s intensity and polarity (5, 6). The ability that formed during slow cooling. Of intense interest from a mag- to extract this paleomagnetic information only recently became netic perspective is the “cloudy zone,” a nanoscale intergrowth possible with the advent of high-resolution X-ray magnetic imag- containing tetrataenite—a naturally occurring hard ferromagnetic ing methods, which are capable of quantifying the magnetic state mineral that
    [Show full text]
  • Meteorites: Rocks from Space
    Learning more... Meteorites: rocks from space Meteorites: Rocks from space It has been estimated that 100,000 rocks from space tonnes of extraterrestrial material Every year the Earth is showered by reach the Earth’s surface every year. It extraterrestrial material falling from can be anything from fine dust to space. The Museum’s mineralogy and metallic masses weighing many tonnes. petrology collections include a small Extraterrestrial material that falls towards the holding of meteorites, and a display of Earth is classified by size. The majority of this some of this material is on show in the material is in the form of tiny particles called rocks and minerals aisle of the main micrometeorites. They fall continuously, and court, along with a large touchable arrive unnoticed. specimen that fell in Nantan in China. Meteors or ‘shooting stars’ are often seen in a clear night sky. They are larger dust particles and small rocky fragments, many no more than a gram in weight, which are burnt up by friction as they fall through the Earth’s atmosphere. Meteorites are larger pieces of rock that reach the Earth’s surface without getting burnt up in the atmosphere. A meteorite whose arrival has been witnessed is called a fall. Meteorites discovered without a known time of fall are The Nantan meteorite called finds. All meteorites, falls and finds, are This meteorite comes from either Lihu or Yaozhai town in named after the place where they were picked Nantan County, Guangxi, China, where it fell in 1516. It is an iron meteorite weighing over 155 pounds (71kg), and is up.
    [Show full text]
  • Handbook of Iron Meteorites, Volume 3 (Willow Creek – Wood's Mountian)
    Willamette - Willow Creek 1321 Stage four would be the penetration of the atmos­ Williamstown. See Kenton County phere. However, no remnants of the associated sculpturing (Williamstown) are to be seen today. The fusion crust and heat-affected o:2 zones are all removed by weathering. Immediately after its landing, the external shape of Willamette may have re­ Willow Creek, Wyoming, U.S.A. sembled that of Morito rather closely. Stage five is the final long-term exposure in the humid 43°26'N, 106° 46'W; about 1,800 m Oregon valley forest during which the deep cavities, partially penetrating and generally perpendicular to the Coarse octahedrite, Og. Bandwidth 1.40±0.25 mm. Partly recrystal­ topside of the mass, were formed. While no large-scale lized . HV 152±6. texture, such as silicate inclusions, can be considered Group IIIE. 8.76% Ni, about 0.35% P, 16.9 ppm Ga, 36.4 ppm Ge, responsible for the curious corrosion progress, it is possible 0 .05 ppm lr. that the very distinct troilite filaments have aided in the weathering. These lanes of fine-grained troilite, kamacite HISTORY and taenite would probably provide easy diffusion paths A mass of 112.5 pounds (51 kg) was found by John studded with electrochemical cells and with dilute sulfuric Forbes of Arminto, Wyoming, near Willow Creek, Natrona acid from decomposed troilite, where the kamacite phase County, about 1914. For a long time it was in the would provide the anodic areas and dissolve first. The final possession of the Forbes family, but in 1934 the meteorite product, the deeply carved Willamette mass, must, however, be seen to be believed.
    [Show full text]
  • TRACE ELEMENT COMPOSITION and CLASSIFICATION of Ni-RICH ATAXITE ONELLO
    81st Annual Meeting of The Meteoritical Society 2018 (LPI Contrib. No. 2067) 6176.pdf TRACE ELEMENT COMPOSITION AND CLASSIFICATION OF Ni-RICH ATAXITE ONELLO. K. D. Litasov1,2, A. Ishikawa3, A. G. Kopylova4, N. M. Podgornykh1, 1Sobolev Institute of Geology and Mineralogy, SB RAS, 3 Koptyuga Ave, Novosibirsk, 630090, Russia ([email protected]); 2Novosibirsk State University, 2 Pirogova st, Novosibirsk 630090, Russia; 3Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152- 8550, Japan; 4Institute of Diamond and Precious Metal Geology, 39 Lenina Ave, Yakutsk, 677980, Russia Introduction: Significant amount of iron meteorites remains poorly described and ungrouped. Some of them re- veal anomalous composition, which do not allow classification to the specific known groups [1]. Here we provide new data on the unique Ni- and P-rich iron meteorite Onello, which contains rare high-pressure phosphide allabogdanite [2]. Onello was found in Yakutia (Russia) in 1997. Preliminary study did not allow its clear classification [3]. Methods: Several 0.5-2 cm fragments of meteorite were cut and polished for investigation by scanning electron microscope (Tescan MYRA 3 LMU) with energy-dispersive system X-Max-80 (Oxford Instr.). Trace elements com- position was obtained by LA-ICP-MS (Thermo Scientific Element XR) method at University of Tokyo (Japan). We used homogenous piece of Campo del Cielo iron and synthetic FeNi-metal [4] as standards. Results and discussion: Onello is fine-grained ataxite with matrix consisting of taenite with 23.0-25.4 wt% Ni. Taenite matrix contains numerous tiny inclusions of schreibersite (22-26 wt% Ni), nickelphosphide (44-52 wt% Ni) and allabogdanite (20.6-21.8 wt% Ni).
    [Show full text]
  • Elastic Properties of Iron Meteorites. Nikolay Dyaur1, Robert R. Stewart1, and Martin Cassidy1, 1University of Houston, Science
    51st Lunar and Planetary Science Conference (2020) 3063.pdf Elastic properties of iron meteorites. Nikolay Dyaur1, Robert R. Stewart1, and Martin Cassidy1, 1University of Houston, Science and Research Building 1, 3507 Cullen Boulevard, room 312, Houston, TX 77204, [email protected] Introduction: We investigate the elastic properties of a ture, in the iron meteorites indicates directionality in variety of iron meteorites using ultrasonic (0.5 MHz to 5 physical properties. So, we explored the possibility of MHz) laboratory measurements. Our meteorite samples elastic anisotropy. First, we estimated Vp- and Vs- include Campo de Cielo, Canyon Diablo, Gibeon, and anisotropy from the measured maximum and minimum Nantan. The densities of the meteorites range from 7.15 velocity for each sample. g/cc to 7.85 g/cc. P-wave velocities are from 5.58 km/s to 7.85 km/s, and S-wave velocities are from 2.61 km/s to 3.37 km/s. There is a direct relationship between P-wave velocity and density (approximately quadratic). We find evidence of anisotropy and S-wave splitting in the Gibe- on sample. These measurements may help inform studies related to planetary core properties, asteroid mining, and Earth protection. Iron meteorites are composed of Fe-Ni mixes with Fe content around 90%. The principal minerals are kamacite and taenite with some inclusions mainly repre- sented by troilite, graphite, diamond, gold, quartz, and some others. Iron meteorites are divided into groups based on their structure linked to Ni content: Hexahe- drites (4-6% of Ni), Octahedrites (6-14% of Ni) and Nickel-rich ataxites (>12% of Ni) [1].
    [Show full text]
  • Fersman Mineralogical Museum of the Russian Academy of Sciences (FMM)
    Table 1. The list of meteorites in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences (FMM). Leninskiy prospect 18 korpus 2, Moscow, Russia, 119071. Pieces Year Mass in Indication Meteorite Country Type in found FMM in MB FMM Seymchan Russia 1967 Pallasite, PMG 500 kg 9 43 Kunya-Urgench Turkmenistan 1998 H5 402 g 2 83 Sikhote-Alin Russia 1947 Iron, IIAB 1370 g 2 Sayh Al Uhaymir 067 Oman 2000 L5-6 S1-2,W2 63 g 1 85 Ozernoe Russia 1983 L6 75 g 1 66 Gujba Nigeria 1984 Cba 2..8 g 1 85 Dar al Gani 400 Libya 1998 Lunar (anorth) 0.37 g 1 82 Dhofar 935 Oman 2002 H5S3W3 96 g 1 88 Dhofar 007 Oman 1999 Eucrite-cm 31.5 g 1 84 Muonionalusta Sweden 1906 Iron, IVA 561 g 3 Omolon Russia 1967 Pallasite, PMG 1,2 g 1 72 Peekskill USA 1992 H6 1,1 g 1 75 Gibeon Namibia 1836 Iron, IVA 120 g 2 36 Potter USA 1941 L6 103.8g 1 Jiddat Al Harrasis 020 Oman 2000 L6 598 gr 2 85 Canyon Diablo USA 1891 Iron, IAB-MG 329 gr 1 33 Gold Basin USA 1995 LA 101 g 1 82 Campo del Cielo Argentina 1576 Iron, IAB-MG 2550 g 4 36 Dronino Russia 2000 Iron, ungrouped 22 g 1 88 Morasko Poland 1914 Iron, IAB-MG 164 g 1 Jiddat al Harasis 055 Oman 2004 L4-5 132 g 1 88 Tamdakht Morocco 2008 H5 18 gr 1 Holbrook USA 1912 L/LL5 2,9g 1 El Hammami Mauritani 1997 H5 19,8g 1 82 Gao-Guenie Burkina Faso 1960 H5 18.7 g 1 83 Sulagiri India 2008 LL6 2.9g 1 96 Gebel Kamil Egypt 2009 Iron ungrouped 95 g 2 98 Uruacu Brazil 1992 Iron, IAB-MG 330g 1 86 NWA 859 (Taza) NWA 2001 Iron ungrouped 18,9g 1 86 Dhofar 224 Oman 2001 H4 33g 1 86 Kharabali Russia 2001 H5 85g 2 102 Chelyabinsk
    [Show full text]
  • SEM Studies of a Campo Del Cielo Meteorite Fall
    632 Microsc Microanal 9(Suppl 2), 2003 DOI: 10.1017/S143192760344316X Copyright 2003 Microscopy Society of America SEM Studies of a Campo del Cielo Meteorite Fall E. D. Cabanillas*, T. A. Palacios** * CONICET and Departamento de Combustibles Nucleares, Comisión Nacional de Energía Atómica, Avenida del Libertador 8250, 1429 Buenos Aires, Argentina, email: [email protected] ** Departamento. de Materiales Comisión Nacional de Energía Atómica. We have studied a piece belonging to the Campo del Cielo meteorite fall by mean of SEM, EDS, chemical analysis, xrd and optical metallography. The analyses showed that it is an iron hexahedrite meteorite with small inclusions of schreibersite and rhabdite iron-nickel phosphides in a kamacite matrix of approximately 95 wt.% Fe, 5 wt.% Ni and 373 ppm of C. We have found Neumann bands differentiated from taenite streaks. Meteorites are bodies with full of interest. Meteorites alloy are not found naturally on Earth and its phases can not be man made, the processes they are related with involve long time; for example the Widmanstätten pattern is only possible to grow during million of years of cooling, [1][2][3]. This meteorite, of approximately 2 kg is one of the smaller pieces of the fall, which took place 5000 years ago, in the Chaco Province in Argentine, and it is considered as one of the biggest. Many pieces are at present in situ and others distributed in very important museums around the world. A slide was cut, polished and etched with Nital 4, then it was xrd analyzed with Cu k" radiation. The surface of this meteorite is smooth without regmaglypts, dark brown and removable.
    [Show full text]
  • Metallographic Techniques for Iron Meteorites
    A Note on Metallographic I Meteorites George F. Vander Metal Physics Research, Carpenter Technology Corporation, Reading, PA 19612 Meteorites are particularly fascinating subjects for metallographic examination, not merely because of their extraterrestial origin, but also because of the rich variety of microstructural constituents encountered. While their structure can be assessed use of the familiar nital and picral etchants used extensively for steels, application of selective etchants, including those that produce selective coloration, greatly increases the amount of infor­ mation obtained by light microscopy. The article describes efforts to preferentially darken or color microstructural constituents in iron meteorites: kamacite (ferrite), Neumann bands (mechanical twins), taenite (austenite), cohenite (Fe-Ni carbide similar to ce­ mentite), martensite and schreibersite/rhabdite (Fe-Ni phosphides). The influence of con­ centration gradients, deformation, and reheating on the structure can be clearly observed by the use of tint etchants. INTRODUCTION iron portion of meteorites, as in the iron meteorites, is opaque to and Meteorites have fascinated engineers and requires reflected-light studies. scientists for many years. Research on me­ The classification of iron meteorites is a teorites began with mineralogists and ge­ complex Classification is based on ologists and the major phases and constit­ macrostructural and microstructural char­ uents in iron meteorites were identified acteristics or chemical ,-,,..,.,.,,.. -e-,,..,.,,i.-ir'n and named prior to Henry Clifton Sorby's Ga, Ge, Ir contents). The two "UQYIPn,,, first observation in 1863 of the microstruc­ tunately. are consistent. In terms, ture of polished and etched manmade met­ there are three categories of iron meteo- als. Iron meteorites are but one of several rites-hexahedrites, and general categories of meteorites.
    [Show full text]
  • New Insights Into the Mineralogy and Weathering of the Meridiani Planum Meteorite, Mars
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Stirling Online Research Repository Meteoritics & Planetary Science 46, Nr 1, 21–34 (2011) doi: 10.1111/j.1945-5100.2010.01141.x New insights into the mineralogy and weathering of the Meridiani Planum meteorite, Mars Iris FLEISCHER1*, Christian SCHRO¨ DER2,Go¨ star KLINGELHO¨ FER1, Jutta ZIPFEL3, Richard V. MORRIS4, James W. ASHLEY5, Ralf GELLERT6, Simon WEHRHEIM1, and Sandro EBERT1 1Institut fu¨ r Anorganische und Analytische Chemie, Johannes-Gutenberg-Universita¨ t Mainz, Staudinger Weg 9, 55128 Mainz, Germany 2Universita¨ t Bayreuth und Eberhard Karls Universita¨ tTu¨ bingen, Sigwartstr. 10, 72076 Tu¨ bingen, Germany 3Senckenberg Forschungsinstitut und Naturmuseum Frankfurt, Sektion Meteoritenforschung, Senckenberganlage 25, 60325 Frankfurt, Germany 4ARES Code KR, NASA Johnson Space Center, 2101 NASA Parkway, Houston, Texas 77058, USA 5Mars Space Flight Facility, School of Earth and Space Exploration, Arizona State University P.O. Box 876305, Tempe, Arizona 85287–6305, USA 6Department of Physics, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada *Corresponding author. E-mail: fl[email protected] (Received 18 November 2009; revision accepted 15 October 2010) Abstract–Meridiani Planum is the first officially recognized meteorite find on the surface of Mars. It was discovered at and named after the landing site of the Mars Exploration Rover Opportunity. Based on its composition, it was classified as a IAB complex iron meteorite. Mo¨ ssbauer spectra obtained by Opportunity are dominated by kamacite (a-Fe-Ni) and exhibit a small contribution of ferric oxide. Several small features in the spectra have been neglected to date.
    [Show full text]
  • Part 1. Fe-Ni Taenite Cooling Experiments
    Meteoritics & Planetary Science 38, Nr 11, 1669–1678 (2003) Abstract available online at http://meteoritics.org Ordinary chondrite metallography: Part 1. Fe-Ni taenite cooling experiments R. J. REISENER and J. I. GOLDSTEIN* Department of Mechanical and Industrial Engineering and Department of Geosciences University of Massachusetts, Amherst, Massachusetts 01003, USA *Corresponding author. E-mail: [email protected] (Received 16 January 2003; revision accepted 1 December 2003) Abstract–Cooling rate experiments were performed on P-free Fe-Ni alloys that are compositionally similar to ordinary chondrite metal to study the taenite → taenite + kamacite reaction. The role of taenite grain boundaries and the effect of adding Co and S to Fe-Ni alloys were investigated. In P-free alloys, kamacite nucleates at taenite/taenite grain boundaries, taenite triple junctions, and taenite grain corners. Grain boundary diffusion enables growth of kamacite grain boundary precipitates into one of the parent taenite grains. Likely, grain boundary nucleation and grain boundary diffusion are the applicable mechanisms for the development of the microstructure of much of the metal in ordinary chondrites. No intragranular (matrix) kamacite precipitates are observed in P-free Fe-Ni alloys. The absence of intragranular kamacite indicates that P-free, monocrystalline taenite particles will transform to martensite upon cooling. This transformation process could explain the metallography of zoneless plessite particles observed in H and L chondrites. In P-bearing Fe-Ni alloys and iron meteorites, kamacite precipitates can nucleate both on taenite grain boundaries and intragranularly as Widmanstätten kamacite plates. Therefore, P-free chondritic metal and P-bearing iron meteorite/ pallasite metal are controlled by different chemical systems and different types of taenite transformation processes.
    [Show full text]
  • Schreibersite Growth and Its Influence on the Metallography of Coarse-Structured Iron Meteorites
    SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES • NUMBER 21 Schreibersite Growth and Its Influence on the Metallography of Coarse-Structured Iron Meteorites Roy S. Clarke, Jr. and Joseph I. Goldstein SMITHSONIAN INSTITUTION PRESS City of Washington 1978 ABSTRACT Clarke, Roy S., Jr., and Joseph I. Goldstein. Schreibersite Growth and Its Influence on the Metallography of Coarse-Structured Iron Meteorites. Smithson- ian Contributions to the Earth Sciences, number 21, 80 pages, 28 figures, 20 tables, 1978. —The role that schreibersite growth played in the structural development process in coarse-structured iron meteorites has been examined. The availability of many large meteorite surfaces and an extensive collection of metallographic sections made it possible to undertake a comprehensive survey of schreibersite petrography. This study was the basis for the selection of samples for detailed electron microprobe analysis. Samples containing representative structures from eight chemical Groups I and IIAB meteorites were selected. Electron microprobe traverses were made across structures representative of the observed range of schreibersite associations. Particular emphasis was placed on schreibersite-kamacite interface compositions. An analysis of these data has led to a comprehensive description of the structural development process. Massive schreibersite, one of the four major types of schreibersite encoun- tered, may be accounted for by equilibrium considerations. Subsolidus nuclea- tion and growth with slow cooling from temperatures at least as high as 850° C, and probably much higher, explain the phase relationships that one sees in meteorite specimens. The retention of taenite in the octahedrites establishes that bulk equilibrium did not extend as low as 550° C. Schreibersite undoubtedly continued in equilibrium with its enclosing kamacite to lower temperatures.
    [Show full text]