Alf Olav Larsen (ed), Svein Arne Berge, Frode Andersen, Sven Dahlgren, Knut Edvard Larsen and Ingulv Burvald: The Langesundsfjord - History, Geology, Pegmatites, Minerals

 

Brøgger’s 1890 monograph on the minerals of the syenitic pegmatites of what we today call the Larvik plutonic complex was a monumental work and a great achievement. It occupies a single, large volume of Zeitschrift für Krystallographie. The individual minerals are meticulously described in 663 pages. In addition, Brøgger included a 235 pages long summary of the geology of the whole Oslo Region, a Permian rift system. Brøgger (1851-1940) was 39 years of age at the time of publication, had worked as a professor of mineralogy at Stockholms Högskola since 1881, and became professor at the University of Oslo in 1890, the same year his monograph appeared. No doubt there was a connection between the chair he was offered in Oslo and the publication of the monograph.
The mineralogical investigation of the syenitic pegmatites of the famous Langesundsfjord area, in the south-eastern part of the Larvik plutonic complex, commenced long before Brøgger’s time. Starting with pyrochlore in 1826, eleven new mineral species that are still valid today were described from the area until 1877 by people like Wöhler, Esmark, Berzelius, Erdmann, Scheerer, Weibye and Paijkull. These persons are portrayed in the present book. Brøgger was able to describe eight new species in his publications from 1884 to 1890. Since then, five new species have been described from the area, and the editor of the present book has been involved with all of them: gadolinite-(Ce) (1978), chiavennite (1983), tvedalite (1992), grenmarite (2004) and eirikite (approved 2007), and was recently honoured by the new species alflarsenite (2009). This leads to a total of 26 mineral species for which  the various sites in the Larvik plutonic complex are type localities.
In this book, A.O. Larsen describes in detail about 185 minerals from these occurrences. The information on individual localities and mineral associations is a valuable supplement. Such a plethora of minerals is typical of areas of syenitic pegmatites elsewhere, and the Larvik pegmatites are in the same league as the renowned occurrences in the Kola Peninsula (Russia), Mont Saint-Hilaire, Quebec (Canada) and Ilímaussaq (Greenland).
The publication of this up-to-date account by A.O. Larsen and his co-authors 120 years after Brøgger is a milestone in Norwegian mineralogy. We must remember that it is the work of amateurs and mineral collectors that has contributed most to the knowledge of Norwegian mineralogy in recent years. It must be noted with embarrassment that Norway is today a country without an academic chair in mineralogy. Typically, it was not possible to publish the present book in Norway.
Mr Larsen is not, as you might think, a professionally educated mineralogist. Born in 1952, his background is in engineering and electronics. He was 1974 to 1980 employed as a technician at the Department of Geology, University of Oslo, and has been working since then at the Research Centre of Norsk Hydro (now StatoilHydro) in Porsgrunn. As a self-taught mineralogist, his scientific achievements, including involvement in the description of six new mineral species, are remarkable.
There is still a lot of research to be done in the Larvik plutonic complex, including the mineralogy of the associated syenitic pegmatites. The structure, petrology and geochemistry of the gneissic syenite in the Langesundsfjord area (Brøgger’s ditroite) should be studied by modern methods. Fluid inclusion studies, mineral chemistry, mineral stability relations and isotope geochemistry of rocks and minerals should prove to be fertile fields of investigation.

 

Gunnar Raade
(Senior Curator of Minerals Emeritus)