Alkaline Rocks and Carbonatites of the World

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Xiluvo, Cura And Nharuchonga (Siluvo)


Occurrence number: 
Longitude: 34.07, Latitude: -19.25

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.

A large quarry has been in operation on the carbonatite for many years producing aggregate and limestone for cement (Vail, 1962; Cilek, 1989).
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.
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith