Melt inclusions trapped in Cr-spinel in mid-ocean ridge picrites (FAMOUS area, Atlantic Ocean) were studied using a heating stage and analyzed with both electron and ion microprobes. This new technique can provide information on the most primitive magma compositions, olivine 'spine melt' compositional relationships, crystallization temperature and geochemical diversity of parental melts. The study of melt inclusions in spinel can be applied to different high-Mg suites to show the effects of shallow level fractionation, mixing and contamination that usually affect the composition of volcanic rocks and glasses.