An estimation of the uranium potential of Finnish bedrock

Only about 3% of the bedrock in Finland (337,000 km2) is exposed; the rest is covered by transported glacial or glaciofluvial drift. About 10% of the drift is covered by lakes and 30% by peat land. The thickness of the drift averages 7 m. The bedrock is composed of Archean and Proterozoic formations, almost all of which were metamorphosed in the Precambrian era. Uranium occurs commonly in refractory minerals but also as uraninite and its secondary minerals in a wide variety of host rocks. The known uranium deposits are associated with quartzites and conglomerates, carbonatites, pegmatites, albitites and shear zones in different rock types. The first stage of uranium exploration consists of reconnaissance survey by airborne radiometrics and/or lake sediment geochemistry. The follow-up stage comprises car-borne scintillometry, terrain geophysics, detail geochemistry and diamond drilling. About US $700,000 are spent annually on uranium exploration. The four best occurrences might produce a total of 2700 t U at a cost of US $80-130/kg U. By 1985 Finland will be needing 2130 t natural uranium for its four power plants. (author)