Ultrabasic lunar samples.

FOUR rock fragments from the Apollo 14 samples have ultra-basic affinities. The principal distinguishing features are olivine and pyroxene with an Fe/(Mg+Fe) atomic ratio below 0.2 by contrast with Fe-rich minerals of recognized lunar rock types including norite, mare basalt, gabbroic anorthosite and anorthosite (see Fig. 1). The presence in some breccias and soils of individual grains of high-Mg olivine and pyroxene suggests that ultrabasic components may be common even though large holocrystalline specimens have not been found: this in turn has important implications regarding differentiation on the Moon.