The Takarindoha volcanic field covers about 25x5 km with smaller outliers to the north and south and another close to the coast to the east, immediately west of the town of Vatomandry (Besairie, 1969a). The rocks are essentially olivine nephelinites and melilitites, referred to by Lacroix (1923) as ankaratrites. Olivine phenocrysts are ubiquitous and abundant with those of titanaugite less so; the matrix comprises microlites of the same pyroxene, titanomagnetite, abundant nepheline and a little biotite and perovskite. Rocks containing euhedral melilite, together with nepheline, are widespread throughout the field, but the outlier near Vatomandry is made of a melilitite free of nepheline (Lacroix, 1923). Amongst the available analyses of these rocks (Lacroix, 1923) one has K2O>Na2O which later led Lacroix (1938) to conclude that an altered mineral in this rock was more probably leucite than hauyne.