Dzhangylakh

This is a 4 km diameter intrusion which has a zonal structure. Three intrusive phases have been distinguished: (1) malignites, which occupy the outer part of the complex, (2) larvikites, which form an inner ring and (3) a central stock consisting of amphibole syenite porphyry. Small dykes and lenses of nepheline syenite cut the rocks of phases (1) and (2). Minor areas of pseudoleucite porphyry, that could be remnants of extrusive rocks, are found. The nepheline syenites comprise prismatic grains of anorthoclase, anhedral grains of nepheline, biotite, aegirine or aegirine-augite and alkali amphiboles, either arfvedsonite or riebeckite. Accessory minerals include titanite, apatite, titanomagnetite and brown garnet.