A COMPARISON OF TEXTURAL AND CHEMICAL FEATURES OF SPINEL WITHIN

Lunar mare basalts contain abundant Ti- and Crrich oxide minerals. The spinels display a variety of textures including composite grains of chromite and ulvospinel that have both optically sharp and gradational contacts. EMP profiles for Cr and Ti across these contacts show that they are both chemically sharp and exhibit a gap in both Cr and Ti. Compositional ranges reported in this study agree well with data presented by El Goresy [1], who reported a compositional gap in lunar basalt 12063 and none in 12018. However, we maintain that a compositional gap does exist in the 12018 spinel.