Category：Mineral

Year：Undated

Size:Width:39 x Height28.5 (cm)

Weight:1.99kg

Introduction：Meteorites are space materials falling onto the Earth’s surface. They are compositionally classified into three categories, including iron meteorite with metal content > 90%, stony iron meteorite with metal content > 50%, and stony meteorites that contain two subgroups; chondrites having ~10% metals and achondrites containing ~1% metals. While meteorites of these three categories can be readily distinguished by the proportions of metal luster areas, the iron meteorites resemble slags from steel-making processes and achondrites are similar to terrestrial basaltic rocks, imposing difficulties on meteorite identification.

Iron meteorites are iron and nickel alloys. At temperatures higher than 850 oC, taenite is the stable phase. Upon slow cooling, the low-nickel kamacite precipitates along the crystal faces of taenite, resulting in two or three sets of parallel lamellae that forms the so-called “Widmanstatten pattern”. Such as pattern can only be produced by slow cooling that does not occur during steel-making process. Therefore, the “Widmanstatten pattern” is an important feature for identifying meteorites.

Accession Number:0003740