Pahtavaara gold mine is hosted by the predominantly pyroclastic, voluminous ultramafic volcanics of the Sattasvaara komatiite complex, part of the 2.05Ga Savukoski group (Mutanen, 1997). Least altered komatiites consist of a talc-chlorite assemblage resulting from regional greenschist facies metamorphism. Extrusive ultramafics, including pillow lavas and hyaloclastites are intercalated with minor sedimentary lenses, comprising predominantly carbonaceous shales and coarse, crystalline actinolite-tremolite assemblages believed to be the alteration product of a more pyroxenitic volcanic phase.
At Pahtavaara Mine the coarse-grained amphibole dominated lithologies, dip and plunge subvertically to the west-southwest within the larger, more diffuse, amphibole porphyroblast alteration domain which overprints the talc schists. Mineralisation is hosted predominantly by:
Gold mineralisation is identified in two phases: early fine grained and a later, more coarse-grained phase. Both are ‘free’ gold and the deposit exhibits predominantly non-refractory metallurgical characteristics.
Gold at Pahtavaara was previously mined from two main zones Samurai and DB with the Karoliina and Lansi zones discovered towards the end of the last period of ownership in 2013. Recent work by Rupert has generated three new targets at Harpoon, NFE and T-Zone.
In April 2018, Rupert reported an Inferred mineral resource at a 1.5 g/t Au cut off grade of 4.6 Mt at a grade of 3.2 g/t Au (474 koz). A link to the full National Instrument 43-101 report can be found below
High voltage electrical power is transmitted directly via the main line located 5 km south of the mine. Mine access is by road.
Surface infrastructure at the Pahtavaara mine incudes a heavy vehicle workshop, administration building, two core sheds and a processing plant.
In the first five years of operation over 2 million tonnes of ore was mined from three open pits but from 2006 to 2014 mining was from underground with ramp access.
There has been some 35km of underground 5m x 5m tunnelling developed since operations commenced. Mining was previously undertaken by contractor using long hole stoping methods
Pahtavaara has a working mill with capacity of over 1400tpd. It has a track record of extremely low processing costs due to low power costs and a simple flow sheet comprising a primary crusher, autogenous mill, cyclones, shaking tables, spirals and flash flotation. There is a permitted tailings facility with multiple years of existing capacity and potential to be expanded.