Date of recognition of deposit is carved in soapstone with a wooden stick. The deposit were recognised during a joint reconnaissance trip to the area in September 2000 by geologists from NGU and the landowner Statskog.
Soapstone had, however, also been discovered in this area earlier during geological mapping in both 1929 and in the mid-1980ies, but this was the first time that the enormous industrial potential of the deposits was emphasized. During the subsequent years 2001-2006, NGU and Statskog carried out detailed mapping and large-scale sampling in combination with thorough analyses of mineralogy and chemistry. The soapstone has also been evaluated as a source for dimension stone and has to a certain extent also been tested as a source for talc flotation.
Alterations of soapstone at Linnajavri. Photo: I. Lindahl & L. P. NilssonThe ultramafic rocks are regarded as ophiolite fragments, with serpentinite and soapstone alteration that has probably taken place at an early, oceanic stage. Later the ophiolite (oceanic crust + uppermost mantle) was obducted, exposed for weathering and then strongly eroded and dismembered. A significant dismembering of the crust and mantle may also well have taken place even at an early, oceanic stage as seen at other Caledonian ophiolites. Finally, the fragmented remains of the ophiolite were incorporated into Caledonian nappes being thrusted onto the Precambrian granitic basement of continent Baltica. The geology of the area is dominated by tectonic nappes and minor flakes of rocks separated by a fairly dense net of tectonic melange zones. In the Linnajavri area the relatively flat-lying Caledonian nappes constitutes two open synforms with weakly dipping to undulating axes towards the east-southeast. Granitic basement is found to the west and a large area of Caledonian rocks is found to the east on the Swedish side of the border.
A synform at Linnajavri
The volume of soapstone derived from serpentinised dunite and peridotite is uncommonly large. Around twenty soapstone bodies contain more than one million tons each. The largest body, Kleberflåget, has an estimated reserve of more than 50 million tons. In total the reserves in these bodies have been estimated to approximately 100 million tons. It is a geological potential for large additional resources in the area, especially in the south, most likely 3-5 times the number of estimated reserves.
The distance from the central part of the deposit area and the deep-water harbour at Leirfjord is c. 35 kilometres, with 26 km of existing road, and 8-10 km with no road. The deposits are located in a mountainous area 600-1200 m.a.s.l. No signs of previous use or exploitation of the soapstone have been recognized. Parts of the deposit area will be subjected to special environmental regulations.
Further information about the Linnajavri talc and soapstone deposit will be available soon.