The origin of fassaitic augite in the alkali basalt suite of the Hocheifel area,Western Germany

Fassaitic augite (augite 3) occurs in clinopyroxenite fragments with cumulus textures or as anhedral crystals in alkali basalts and nepheline basanites of the Hocheifel Area. Rimming of augite 3 by phenocrystic augite (augite 2) followed by groundmass augite (augite 4) defines the sequence of the clinopyroxene crystallization. Fassaitic augites from other alkali-basalt series reveal clinopyroxene crystallization trends of increasing ferri Tschermak's molecule and concomitant acmite as fractionation proceeds. This trend appears to be much more common than previously assumed.Dedicated to K. Jasmund in honor of his sixtieth birthday.