Mössbauer Spectroscopy of Chondrules and Matrix from a Stony Meteorite (ALHA 77278)

Mössbauer investigations of the unequilibrated chondrite ALHA 77278 are reported. The chondrules studied are found to contain the silicates olivine and pyroxene, and one of the chondrules furthermore contains kamacite (b.c.c. iron-nickel alloy). The investigations of a powder mixture of chondrules and matrix show that the meteorite, besides the silicates and the kamacite, contains troilite and taenite (f.c.c. iron-nickel alloy). The taenite is found as a ferromagnetic, totally disordered alloy containing more than 40% nickel. The results are discussed within the framework of the theories about the condensation sequence of minerals in the early solar system.