Nepheline gneiss is indicated on the 1:1,000,000 geological map as occurring along the border with Malawi.
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The distribution of many of the occurrences of alkaline rocks and carbonatites in Mozambique, and adjacent areas of Malawi and Zimbabwe, are illustrated and listed by Vail (1964, Fig. 1 and Table 1) and for central Mozambique by Woolley and Garson (1970, Fig. 2). A useful account of the economic deposits of rocks and minerals, which contains much information not easily obtained elsewhere, is that of Cilek (1989). Most of the occurrences in northern Mozambique have been taken from the 1:1,000,000 (Carta Geologica, 1987) geological map of the country, which was made under contract; it did not prove possible to consult the accompanying reports.
Nepheline gneiss is indicated on the 1:1,000,000 geological map to occur along the border with Malawi.
The syenite ring complex of Salambidwe rises to a hill through which the international boundary between Mozambique and Malawi passes, with the complex distributed approximately equally between the two countries. The description will be found under Malawi (No. 103-00-042).
Cone Negose is located immediately north of the fault system that defines the northern margin of the mid-Zambezi trough (rift). It forms a hill and is intruded into Precambrian metasedimentary rocks which are cut by numerous Karoo dolerite dykes.
A soil sample collected from the Lualadzi River just upstream from the village of Inhavunduea, which is approximately 20 km north of Zumbo, contained 3700 ppm Nb and this fact, combined with the presence of at least three circular structures apparent on Landsat photographs, suggests that carbona
Mount Chandava is a small hill 1.2 km long a geological map of which is given by Dias (1961) but with no geological or petrographic descriptions.
This intrusion forms a hill west of Chandava (No. 114-00-017). No geological description has been traced but petrographic notes by Pinto Coelho (1961) indicate the principal rock types to be syenite, trachyte and gabbro; a fine-grained carbonatite is also described.
Chuara is a sill which forms a hill some 300 m high and 3 km in length. The sill is probably 150-190 m in maximum thickness and rests on Karoo shales which are metamorphosed, as are dolerites cutting the shales.
Muambe is a circular carbonatite plug which with its aureole of feldspathic rocks is 5 km in diameter. The feldspathic rocks form a circular ridge, rising to some 400 m above the surrounding plain, that envelopes an inner crater-like depression within which are craggy hills of carbonatite.
A syncline plunging to the southeast, which is traversed by the Zambezi River, contains a thick succession of upper Karoo (Stormberg) basalts and rhyolites which are overlain unconformably by alkaline lavas - the Lupata volcanics.