Silicon in the Metal Phase of Enstatite Chondrites

Abstract

I HAVE recently measured the lattice parameters of the metal phases from a number of chondrites. In five common varieties the kamacite lattice parameter was within the range 2.8682 ± 0.0005 Å. This corresponds to an average of 5 per cent nickel in solid solution¹. Owen and Burns¹ found that the kamacite lattice parameters from 15 meteoritic irons were within the range 2.8686 ± 0.00015 Å. This is in good agreement with the above result, and indicates the presence of about 6 per cent nickel. I also examined the kamacite from 6 enstatite chondrites. In these, the lattice parameters were found to be abnormally low, and below that of pure iron (Table 1). The metal phases of these chondrites had previously been analysed and found to contain normal amounts of nickel—between 6 and 8 per cent. Since the solid solution of nickel ‘increases’ the lattice parameter of pure iron, it was inferred that appreciable amounts of some other component were also present in solid solution and that this component had caused the lattice parameter to contract.