Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences



Occurrence number: 
Congo (Kinshasa)
Longitude: 29.08, Latitude: -1.22

2.5 km northwest of Bishusha on the eastern side of the Bigogo River, Denaeyer (1958) noted the occurrence of nepheline syenite. Details of the extent and field relationships are not available. The rock comprises microcline perthite, nepheline, which may have inclusions of sodalite with a dactylotypic texture, green biotite, locally muscovite replacing nepheline, melanite, titanite and accessory apatite. Another variety of the rock contains more sodalite and a sodic amphibole described as 'osannite' (now riebeckite). Biotite syenites and granites outcrop three kilometres west of Bishusha the former being exceptionally sodic (8.01% Na2O; 0.71% K2O), but they are not peralkaline. Rock analyses are given.

DENAEYER, M.-E. 1958. Les syénites feldspathoïdiques du Kivu et leur rôle dans la genèse des laves des Virunga. Bulletin de la Société Belge de Géologie de Paléontologie et d'Hydrologie (Bruxelles), 67: 459-87.
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith