The locality consists of several nepheline syenite pegmatites, usually 10-30 cm thick, often rather irregularly cross-cutting. Nearly 60 different mineral species have been found in the dikes. Because of its complex and scientifically interesting mineralogy, the locality has been protected by law since 1984.
Refs.:
- Engvoldsen, T., Andersen, F., Berge, S.A. & Burvald, I. (1991): Pegmatittmineraler fra Larvik ringkompleks. STEIN 18(1),15-71
-Larsen, A. O., Raade, G. & Sæbø, P. C. (1992): Lorenzenite from the Bratthagen nepheline syenite pegmatites, Lågendalen, Oslo Region, Norway. Norsk Geologisk Tidsskrift, 72, 381-384.
-Raade, G.& Mladeck, Michel H.(1977): Parakeldyshite from Norway. Canadian Mineralogist 15,102-107
- Sæbø, P.(1966).Contribution to the mineralogy of Norway no.35. The first occurences of the rare mineral barylite, Be2BaSi2O7, in Norway. Norsk Geologisk Tidsskrift 46, 335-348
- http://home.c2i.net/aolarsen/Pegmatites.htm
