A new classification of Nyirábrany, an ordinary chondrite from Hungary
Mészáros M., Kereszturi A., Ditrói-Puskás Z.
Vol. 3, Nos. 1–2, 2014, 19–32
Publishers: Wrocław University of Technology, Faculty of Geoengineering, Mining and Geology; Polish Meteorite Society
ordinary chondrite, moreover to complete its classiﬁcation with a shock stage and a weathering grade. Our new results indicate that Nyirábrany could be a transition type between the L and LL chondrites. The main mineral phases of Nyirábrany are olivine, pyroxene and opaque minerals (e.g. Fe-Ni metal, troilite, chromite), minor constituents are plagioclase, Cl-apatite, cristobalite and glass. The Fe-Ni metal content (1.32 vol%) of Nyirábrany is typical of the LL group, the Fa-content of olivines (26.71 mol%) is between the range of the L and LL types, while the Fs-content of the low-Ca pyroxenes (20.51 mol%) is typical of the L-chondrites. Chondrules appear in diﬀerent sizes, mineral compositions and textures. The textural and mineralogical features
(e.g. mostly homogeneous silicate minerals, dominance of clinopyroxenes, recrystallized matrix, well-deﬁned chondrules) indicate petrological type 4-5 for Nyírábrány. The shock stage and the weathering grade of this meteorite were examined for the ﬁrst time. On the basis of the observed optical and textural features of the olivine grains (e. g. sharp optical extinction, irregular and
planar fractures) Nyirábrany has an S2 shock stage. About 30–40% of the opaque phases are aﬀected by oxidation, which shows a W2 weathering grade.