stripes
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.
CILEK, V.G. 1989. Industrial minerals of Mozambique. Geological Survey, Prague. 326 pp.GITTINS, J. 1966. Summaries and bibliographies of carbonatite complexes. In O.F. Tuttle and J. Gittins (eds), Carbonatites, 417-570. John Wiley, New York.VAIL, J.R. 1962. Mount Xiluvo vent, Mozambique. Annual Report, Research Institute of African Geology, University of Leeds, 6: 16-7.
