Glasses in the system AlF3-[MgF2-CaF2-SrF2-BaF2]-YF3 (i.e., AMCSBY) have been optimised to reduce devitrification on quenching the melt. Cast specimens are in large part crystal-free. Nevertheless, microcrystallites tend to be present in a characteristic distribution within the glass bulk. The morphology and identity of these crystals are discussed especially in relation to the crystallisation which occurs on reheating the glass.