This involves utilising the access level from the wharf as the main drainage system. However, the reserve below sea level terminating to sea requires marginal pumping. The marble typically consists of coarsely crystalline calcite (<5mm) with very small amounts (<0.5%) of acid insoluble recidue (mainly mica, quartz and minor iron pyrite).
Unusually for a marble deposit, the material lacks any appreciable amount of graphite and this aspects is of particular benefit in the production of high brightness ultra-fine ground products for the paper industry.
Geology
The rocks in the Salsbruket area consist of a cover of metapsammites, gneisses, calcsilicate schists, amphibolites and calcitic marbles overlying a basement sequences of porphyroclastic augen gneisses and granites. The marble horizons exposed in the area occur within an undifferentiated sequence of biotite gneiss and amphibolite and appear as three synclinal structures 'nested' within each other. These synclines trend north-east/south-west and have very steeply dipping limbs which are frequently vertical or over-turned. The structures plunge to the south-west and possibly represent the same horizon repeated by folding and faulting.
The westernmost of these structures is located at Hestvika and is currently being exploited by Norkalsitt. The marble horizon is typically 25-35 metres wide and shows a very distinct contact with the adjacent amphibolites and schists. The structure of the horizon is extremely continuous despite minor, shallow-angle, transverse faulting which seldom displaces the marble for more than 1-2 metres. Water movement within the marble deposit is very dependant on fissureflow along the fracture zones. The majority of the current reserve at Hestvika will be available for exploitation without the need for pumping.