?EBY, G.N., WOOLLEY, A.R., DIN, V. and PLATT, G. 1998. Geochemistry and petrogenesis of nepheline syenites: Kasungu-Chipala, Ilomba, and Ulindi nepheline syenite intrusions, North Nyasa Alkaline Province, Malawi. Journal of Petrology, 39: 1405-24.RAY, G.E.?. 1998.