Alkaline Rocks and Carbonatites of the World

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Chiueca (Monte Chiueca)

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Occurrence number: 
005-00-011
Country: 
Angola
Location: 
Longitude: 16.38, Latitude: -11.78

This occurrence forms a hill some 2 km in diameter rising 140 m above the plain. The core of the hill is a coarse syenite which becomes finer grained towards the margins. Andrade (1954) briefly describes a collection of rocks from this locality which vary from aphanitic to porphyritic the latter with phenocrysts of nepheline and sodic pyroxene. One described rock consists of 60% orthoclase, 21% nepheline, 14% aegirine plus aegirine-augite, the latter sometimes zoned, and accessory titanite, magnetite, calcite, cancrinite and apatite. A chemical analysis is given.

References: 
ANDRADE, M. de 1954. Contribution à l'étude des roches alcalines d'Angola (note preliminaire). 19th International Geological Congress, Algiers. Comptes Rendus, 19: 241-52.MACHADO, F.J. de S. 1958. The volcanic belt of Angola and its carbonatites. Publication. Commission for Technical Cooperation in Africa South of the Sahara. Joint Meeting, Leopoldville, 44: 309-17.
Location: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith