Alkaline Rocks and Carbonatites of the World

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Quiculungo And Quilungo

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Occurrence number: 
005-00-004
Country: 
Angola
Location: 
Longitude: 14.28, Latitude: -9.27

10.7 km northeast of Zenza do Itombe the quarry of Quiculungo is sited on a small elevation and contains nepheline syenite and hornblende melteigite (Neiva, 1959). The nepheline syenite comprises perthitic alkali feldspar (72%) in sub-parallel tabular crystals, nepheline (15%) and aegirine-augite, which is rimmed by amphibole, with accessory oligoclase, titanite, biotite, muscovite, ilmenite and apatite. The rock described as a hornblende melteigite comprises 30% nepheline, 20% aegirine-augite and 38% hornblende, with accessory biotite, apatite, titanite and ilmenite. Whole rock analyses are given. Barros (1965) has described phonolites from Quilungo (Zenza do Itombe), which are in a Museum collection, but no field relationships are given. It seems likely that Quiculungo and Quilungo are either the same locality or the former is a quarry within a broader locality going under the latter name. I have not been able to resolve this problem. The phonolites, according to Barros (1965), are divided into four types based on their microscopic features, particularly the nature of the phenocrysts. All the rocks contain nepheline, often as phenocrysts, which may be partly altered to cancrinite, natrolite and calcite, sanidine and 'sodic orthoclase', aegirine and/or aegirine-augite and titanite. Rock analyses of the four types are given.

References: 
BARROS, L.A. 1965. Sobre as rochas feldspatoidicas da região de Zenza do Itombe (Angola). Garcia de Orta. Revista da Junta de Investigações do Ultramar, 13: 427-34.NEIVA, J.M.C. 1959. Rochas com feldspatóides da Pedreira do Quiculungo (Golongo Alto - Angola). Memórias e Notícias. Publicações do Museu e Labóratorio Mineralógico e Geológico da Universidade de Coimbra e do Centro de Estudos Geológicos, 47: 1-10.
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