Phosphide from metorites: barringerite, a new iron-nickel mineral.
Schreibersite, (Fe,Ni)(3)P, and a higher phosphide, barringerite, occur in the Ollague pallasite. The composition of the higher phosphide, determined by electron probe microanalysis, is (Fe(0.58)Ni(0.42)Co(0.003))(1.95)P. It is hexagonal, with space group P62m and a = 5.87 +/- 0.07 angstroms and c = 3.44 +/- 0.04 angstroms. If we assume a primary origin, the new mineral indicates that troilite and schreibersite crystallized at high temperatures. The occurrence of a higher phosphide in a pallasite indicates local nonequilibria within a group of meteorites that are remarkable for their overall degree of equilibrium crystallization.
Buseck
P R
PR