Equilibration temperature of the Kobe meteorite.

Petrography and mineralogy of one of the polished sections of the Kobe meteorite (CK4) are described as a part of the Kobe meteorite consortium. Porphyritic olivine chondrules are dominant and one barred olivine chondrule was observed. Olivine grains both in chondrules and matrix are homogeneous and have compositions of Fo69. Pyroxenes are also abundant in chondrules and matrix. Orthopyroxene and augite grains except for augite grains in chondrules are also homogeneous and have the average compositions of about En73Fs26Wo1 and En44Fs10Wo46, respectively. The homogeneity of these two pyroxene grains is due to parent body metamorphism. The equilibration temperature of the chondrite was estimated to be around 800°C based on pyroxene geothermometers and an olivine-spinel geothermometer. Plagioclase shows compositional variations. Albite-rich (about An40) and anorthite-rich (∼An60) grains were observed in regions of the studied section. The inhomogeneity may be attributed to the miscibility gap close to the inferred metamorphic temperature.