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NWA 10224

Sahara
Purchased in january 2014 in Tagounite (Morocco)
Iron, IID
Total mass : 317.8 g

Specimen in collection :
9.21g slice

Purchased in two pieces while traveling in southern Morocco, this iron meteorite was already remarkable for its « twisted » shape, plastically deformed by stresses experienced during its fall on Earth. Once cut for the analysis, the first idea was to polish one side and attack it with nitric acid. As several scientists discovered the early 19th century, « Siderolithes » as they were then called, or siderites today revealed in about 9 out of 10 cases the geometric characteristics structures, showing an octahedral mesh, called « Widmanstätten figures » (from the name of one of their discoverers). Those figures are the result of the sequential and gradual crystallization of the metal in the meteorite (about 90% iron and 10% nickel in this case) into two separate alloys, the taenite (depleted in iron, nickel-rich) then the kamacite (depleted in nickel, iron-rich) during the slow cooling of the asteroid from which it originated. Such structures do not naturally occur on Earth … In addition to its classification in the octahedrites, chemical analysis of elements revealed some elements in very small quantities (called « trace elements ») as iridium, osmium, gallium and germanium, and showed that NWA 10224 has affinities of composition with a small group of metallic meteorites composed of only 22 members, known as « IID group ».

Additional information

Provenance

  • Fabien Kuntz