The island Stokkøya is rich in a large number of nepheline-syenite pegmatites, some of them hosted in basaltic rocks.
References:
- Brøgger, W.C. (1890): Die Mineralien der Syenitpegmatitgänge der südnorwegischen Augit-und Nephelinsyenite. Zeitschrift für Kristallographie und Mineral.16. 663 pp
- Neumann, H. & Bergstøl, S. (1964): Contribution to the Mineralogy of Norway No 25. Pyrophanite in the southern Part of the Oslo Area. Norsk Geologisk Tidsskrift 44: 39-42 [analysis on pyrophanite from Stokkøya]
- Segalstad, T.V. & Larsen, A.O.(1978): Chevkinite and perrierite from the Oslo region, Norway. American Mineralogist 63,499-505
