Exposures of nepheline syenite covering 700x100 m occurring along the Chiumbe River, and intruding basement gneisses, are described by Correia (1966). The rock is leucocratic and consists of 50% albite (Ab96), 45% nepheline, which is partly altered to cancrinite, rare microcline and accessory magnetite, titanite, biotite, calcite, apatite, perovskite and zircon. An analysis includes 11.84% Na2O and 2.59% K2O.
CORREIA, E.A. 1966. Uma variedade curiosa de sienito nefelínico da Lunda (Angola). Boletim. Serviços de Geologia e Minas Angola. Luanda. 14: 91-6.