Sodalite or hauyne may also be present, but nepheline is typically absent. Rocks of this class occur also in the tuffs of the Phlegraean Fields, near Naples.
In some cases, sodalite or hauyne can be present alongside nepheline in these rocks, although it's more common for them to be absent. These types of rocks are also known to occur in the tuffs of the Phlegraean Fields, near Naples.