The Nature of the Enstatite Rim in Refractory Forsterite-Rich Inclusions: An EBSD Study

Kseniya A. Dugushkina, Stepan V. Berzin, Dmitry A. Zamyatin

Minerals: Structure, Properties, Methods of Investigation. pp 59-63, Conference paper


“Refractory forsterite-rich inclusions are a common component for different classes of chondrites. They belong to one of the first mineral formations of the solar system. Forsterite is characterized by low ferruginosity (Fa 0.2–2.0), enrichment with refractory lithophilic elements (RLE), in particular CaO 0.5–1.0%, Al2O3 up to 0.3%, and at the same time a sharp deficit of MnO. In some refractory forsterite-rich inclusions, a rim is observed consisting of enstatite with a thickness of 5–200 µm. The composition of the enstatite is SiO2 (58.545 wt%), TiO2 (0.24 wt%), Al2O3 (1.04 wt%), Cr2O3 (0.55 wt%), FeO (1.06 wt%), MgO (37.95 wt%), and CaO (0.5 wt%). The article presents the first results of studying enstatite rims of the refractory forsterite-rich inclusions from the Northwest Africa 11781 carbonaceous chondrite using electron backscatter diffraction (EBSD). As a result of the mapping, it has been established that each of the two grains of refractory forsterite is overgrown with a whole individual enstatite grain. The curvature of enstatite individuals and their disorientation up to 40º is observed along the rim.”