Extraterrestrial magnetic minerals

• Published in: Izvestiya. Physics of the solid earth 2012-07, Vol.48 (7-8), p.653-669
• Main Authors: Pechersky, D. M., Markov, G. P., Tsel’movich, V. A., Sharonova, Z. V.
• Format: Article
• Language: English
• Subjects: Dust; Earth and Environmental Science; Earth Sciences; Geophysics; Geophysics/Geodesy; Magnetic properties; Magnetism; Minerals; Natural history; Nickel; Rocks; Sediments; Terrestrial environments
• ISSN: 1069-3513; 1555-6506
• DOI: 10.1134/S1069351312070051

Thermomagnetic and microprobe analyses are carried out and a set of magnetic characteristics are measured for 25 meteorites and 3 tektites from the collections of the Vernadsky Geological Museum of the Russian Academy of Sciences and Museum of Natural History of the North-East Interdisciplinary Science Research Institute, Far Eastern Branch of the Russian Academy of Sciences. It is found that, notwithstanding their type, all the meteorites contain the same magnetic minerals and only differ by concentrations of these minerals. Kamacite with less than 10% nickel is the main magnetic mineral in the studied samples. Pure iron, taenite, and schreibersite are less frequent; nickel, various iron spinels, Fe-Al alloys, etc., are very rare. These minerals are normally absent in the crusts of the Earth and other planets. The studied meteorites are more likely parts of the cores and lower mantles of the meteoritic parent bodies (the planets). Uniformity in the magnetic properties of the meteorites and the types of their thermomagnetic (MT) curves is violated by secondary alterations of the meteorites in the terrestrial environment. The sediments demonstrate the same monotony as the meteorites: kamacite is likely the only extraterrestrial magnetic mineral, which is abundant in sediments and associated with cosmic dust. The compositional similarity of kamacite in iron meteorites and in cosmic dust is due to their common source; the degree of fragmentation of the material of the parent body is the only difference.