Xiluvo is oval in outline, 5x4 km, and forms a ring of low hills. It cuts granitic gneisses and migmatites of the Mozambique Belt and comprises a central carbonatite which is surrounded by volcanic breccias and these in turn by metamorphosed rocks. Little is known of the petrography but the carbonatite is a fine-grained calcite rock containing apatite and pyrochlore. Analyses in Cilek (1989) indicate the carbonatite to be silica-rich (10.5-28.4% SiO2). The breccias enclose variably sized, angular fragments of basement gneiss, volcanic rocks and some carbonatite, set in a calcareous matrix. Calcite and fluorite-lined cavities are common. Carbonate dykes from a few centimetres to several metres wide cut the breccias.Cura is a smaller, 2 km diameter carbonatite centre located 11 km east northeast from Xiluvo, with which it is comparable, and consists of a carbonatite core and breccia rim. Nharuchonga, lying 3.5 km east of Xiluvo, is a small carbonatite plug. A further three small satellite plugs are located 7 km south southeast of Xiluvo.