THORIUM AS AN ENERGY SOURCE - Opportunities for Norway ...

1. Alkaline complexes and their pegmatites
2. Granitic pegmatites
3. Carbonatites
4. Heavy mineral sand
3.1.1 Thorium in Alkaline Complexes and their Pegmatites
Thorium Resources in Norway
Most of the global resources of thorium are found in alkaline rocks and associated pegmatites. In
Norway the major alkaline rock is situated in the Permian Oslo Province. The thorium level is
enhanced in the whole Province and mostly in the southern part. The geochemistry of the rocks,
soil and stream sediments in the Province is well-known. During the last few years, the area has
been investigated by means of airborne radiometric surveys confirming previous findings [12].
In the Langesundsfjord area, including Stokkøy and Arøy, several Th-containing minerals have
been identified. The bedrocks, both intrusive and extrusive rocks, are markedly enriched in
thorium. The concentrations of thorium from the pegmatites are often high, but the volumes
available are not known. Sæteråsen, an extrusive volcanic rock, has been studied, drilled and
mapped, due to the high concentrations of zirconium (Zr), niobium (Nb), yttrium (Y) and REE.
The rock also contains high levels of thorium (500 ppm). Mineral separation performed in 1980
showed, however, that the rock (trachyte) was difficult to exploit with respect to these metals as it
is very fine-grained. A preliminary estimate of the thorium volumes amounts to 8 million tonnes.
Høgtuva in Nordland County has been identified as a potential resource for beryllium (Be), Zr,
REE, U and Th. The beryllium resource has been drilled, and contains 0.5 million tonnes rocks
with thorium (500 ppm). A wide zone of wall rock contains also similar grades of thorium. Thus,
Høgtuva represents a low-grade thorium resource.
3.1.2 Thorium in Granitic Pegmatites
Granites are generally enriched in uranium and thorium, and especially pegmatites are usually
the most enriched phase. The great advantage in exploiting pegmatites is that they are coarsegrained
rocks. However, the grade of thorium in coarse-grained granitic pegmatites is difficult to
estimate.
In the County of Østfold and along the coast of southern Norway from Bamble in Telemark
County to Rogaland, granitic pegmatites containing Th-minerals have been identified. Pegmatites
with Th-minerals were also identified in other granitic terrains, e.g. Nordland County, but these
have not been studied in detail. In the old Ødegården Mine in Bamble, a flat-lying sill containing
0.1 wt% thorium at 100m depth has been reported. Already in 1906, 500 tonnes of the sill were
taken out and thorium enrichment was carried out with some success. However, the information
on this resource is scarce [12].
3.1.3 Thorium in Carbonatites
Carbonatites are exotic magmatic carbonate rocks, and these rocks are often exploited for
phosphorus (P) and REEs. The carbonatites with high thorium levels are those enriched in iron
(Fe) and/or often in magnesium (Mg) as observed in e.g. parts of the Fen complex in Telemark
County. In addition to the Fen complex, known carbonatites in Norway include carbonatites on
the coast of Finnmark (the islands Stjernøy and Seiland). The carbonatites from Stjernøy have
been thoroughly investigated and contain low levels of Th, while the carbonatites at Seiland have
not been examined in detail. On Inderøy, in the inner part of the Trondheimsfjord area, carbonate
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