Tundulu is formed of several hills in a ring around a central vent called Nathace Hill where the majority of the historic surface sampling and drilling was undertaken. The predominate geology at Nathace Hill is REE apatite, REE carbonatites and feldspathic breccia, and comprises a large inner agglomerate vent. Mineral rich carbonatite also occurs at Tundulu Hill east of Nathace and Makhanga Hill west of Nathace and is previously unexplored and prospective for REEs.