Alkaline rocks occur in an elliptical pluton 3x1.5 km elongated east-west, and a smaller crescent-shaped body to the south. The main intrusion is zoned from a marginal syenite, which may contain minor quartz, to a central natrolite syenite in which the natrolite and cancrinite are after nepheline, only rare remnants of which persist. Zoned microcline phenocrysts lie in a groundmass of albite, aegirine, partly replaced by hastingsite, a zoned yellow garnet and zircon. A tentative identification of eudialyte has been made. Magnetite, pyrrhotine and chalcopyrite are locally abundant.