Old Woman Meteorite: microstructures, analyses, and stories
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F. Hogue
Frauke Hogue graduated from Lette Verein in 1965. In 1967 she moved to Los Angeles to work for a fastener manufacturer. While teaching at ASM International Frauke developed “Practical Interpretation of Microstructures” consisting of over 300 mounts. Frauke mentored for Materials Camp in Cleveland and France.
Abstract
The Old Woman Meteorite (OWM), the second largest found in the USA, was located by prospectors in a steep canyon in the Mojave Desert about 20 km south of Highway 66 in March of 1976. Because of its weight of nearly 3 metric tons it had to be airlifted out of the mountains by a US Marine helicopter.
A small triangular metallographic sample, on loan from the University of California Los Angeles, UCLA, was examined by light microscopy and energy dispersive X-ray spectroscopy (EDS) analysis to identify the structures and phases present.
Rhabdites and schreibersite are visible in the as-polished condition. Nital etchant reveals grain boundaries and Neumann bands. Etching with Klemm I colors kamacite grains(ferrite) and Neumann bands in shades of blue and brown according to the crystal orientation. Prism shaped rhabdites stay white. Many rhabdites show cracks at the intersection with Neumann bands.
Three areas with unusual structures were found. EDS dot maps identified one as schreibersite, another area contains troilite, schreibersite, brezinaite and possibly taenite, the third location contains Fe, Ni, P and S.
Kurzfassung
Der zweitgrößte in den USA gefundene Meteorit, der Old Woman-Meteorit (OWM), wurde im März 1976 von Goldsuchern in einer steilen Schlucht in der Mojave-Wüste etwa 20 km südlich des Highway 66 entdeckt. Aufgrund seines Gewichts von nahezu 3 Tonnen musste er mit einem Hubschrauber der US-Marine aus den Bergen geborgen werden.
Zur Bestimmung seiner Gefüge und Phasen wurde eine kleine dreieckige metallographische Probe, eine Leihgabe der Universität von Kalifornien in Los Angeles (UCLA), mittels Lichtmikroskopie und EDX(energiedispersive Röntgenspektroskopie)-Analyse untersucht.
Im polierten Zustand sind Rhabdite und Schreibersit erkennbar. Nital-Ätzmittel bringt Korngrenzen und Neumann-Linien zum Vorschein. Ätzen mit Klemm I färbt Kamacitkörner (Ferrit) und Neumann-Linien je nach Kristallorientierung in Blau- und Brauntönen. Prismenförmige Rhabdite bleiben weiß. Viele Rhabdite weisen an der Schnittstelle mit Neumann-Linien Risse auf.
Gefunden wurden drei Bereiche mit ungewöhnlichen Strukturen. Mittels EDX-Elementverteilungskarten wird ein Bereich als Schreibersit identifiziert, ein anderer enthält Troilit, Schreibersit, Brezinait und möglicherweise Taenit, und der dritte Bereich enthält Fe, Ni, P und S.
About the author
Frauke Hogue graduated from Lette Verein in 1965. In 1967 she moved to Los Angeles to work for a fastener manufacturer. While teaching at ASM International Frauke developed “Practical Interpretation of Microstructures” consisting of over 300 mounts. Frauke mentored for Materials Camp in Cleveland and France.
References / Literatur
[1] Vagn F. Buchwald: Handbook of Iron MeteoritesSuche in Google Scholar
[2] National Geographic Magazine: Invaders From Space. September 1986Suche in Google Scholar
[3] Plotkin, H.; Clark, R. et al.: The Old Woman, California, IIAB iron meteorite. Meteoritics & Planetary Science 47, Nr. 510.1111/j.1945-5100.2012.01348.xSuche in Google Scholar
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Artikel in diesem Heft
- Inhalt
- Editorial
- Editorial
- Metallography of tailings from the Mansfeld copper mining area
- Enhancing precision and safety in metallographic sample preparation: Reduce the stochasticity and workload with robotization
- Electropolishing study of metastable austenitic steel AISI 347 for EBSD analyses
- Examinations on small bronze items from the Hallstatt period burial ground at Mitterkirchen in Upper Austria
- In situ stereomicroscopy chemical and color etching
- Quantification of forming-induced damage in case-hardening steel AISI 5115 by advanced SEM methods
- Microstructures of iron meteorites
- Old Woman Meteorite: microstructures, analyses, and stories
- Titanium alloys with a high β stabilizer content – sample preparation strategies and micrographs
- Microstructural changes in the welding of titanium-stabilized steels
- Development of a preparation method for Bronze Age flanged axes
- Challenges and possibilities of the manual metallographic serial sectioning process using the example of a quantitative microstructural analysis of graphite in cast iron
- Effects of heat treatment on the microstructure and corrosion behavior of manganese aluminum bronzes
- Utilizing nano-computed tomography to characterize the structural nature of industrial minerals
- Use of mobile metallography to assess the extent of damage to high temperature components in power plants
- Picture of the Month
- Picture of the Month
- News
- News
- Meeting Diary
- Meeting Diary
