The Rupert Lapland Project area (Ikkari gold discovery and Pahtavaara mine) is 100% owned by Rupert Finland Exploration Oy & Rupert Finland Oy, wholly owned subsidiaries of Rupert Resources.
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Summary:
The updated Mineral Resource Estimate for the Ikkari gold deposit, the Pahtavaara gold mine and the Heinä Central gold-copper deposit.
All three deposits set out here are considered to be orogenic-style with gold mineralisation associated with low sulphidation alteration.
PAHTAVAARA
The Pahtavaara gold deposit can be described as an orogenic, metamorphic, hydrothermal gold deposit. The Pahtavaara deposit has shown the deposit to lie within a mineralised envelope up to 500 m wide and up to 1.5 km longand that the deposit remains demonstrably open at depth and along strike. In the 1994 Feasibility Study the deposit was described as occurring in a gold-bearing alteration zone covering 100 m x 600 m, dipping 80° to 85° NNW (Davy, 1994).
Pahtavaara is hosted by ultramafic rocks (komatiites to high magnesian basalts). Gold mineralisation is structurally controlled and associated with low sulphidation, polyphase quartz-carbonate veining, multiple deformation phases varying from brittle to ductile and back to brittle and intense alteration, both prograde and retrograde.
Two phases of gold mineralisation have been observed; early fine grained and later, more coarse-grained. Both are ‘free’ gold, as the deposit does not exhibit refractory metallurgical characteristics.
IKKARI
Ikkari is a grassroots discovery, located under 10 to 25 m of transported glacial till cover.
The Ikkari deposit can be described as an orogenic, hydrothermal gold deposit. The deposit to lie within a mineralised envelope of up to 800 m long, 300 m wide and 750 m deep and that the deposit remains demonstrably open at depth and along strike.
Overall, the mineralisation trends at approximately 065° strike and has a strong sub-vertical control. However, within the mineralised halo different grade zones have varying morphology and plunges on a local scale and these are explored later.
Mineralisation at Ikkari occurs in several styles, but in all cases, gold distribution is correlated to the abundance of disseminated pyrite and intensity of veining, which are in turn considered to be controlled by faulting, folding intensity and localisation at lithological contacts.
Ikkari is unusual among orogenic gold deposits in the width of mineralisation when compared to the strike.
Although vein arrays and stockwork zones are considered to be linked to the main gold phase, in that pyrite content increases, there is little consistent relationship between vein density, vein volume, and gold grade. There appears to be a further relationship between gold content, sulphide and late-stage ironoxides. Magnetite-bearing veins and breccias typically contain elevated gold grades, with associated disseminated pyrite, and where late haematite is (also) present, particularly in coarse breccias comprising haematite (+ pyrite) in the matrix, very high grades (>10 g/t Au) are observed.
Mineralisation remains open at depth, down-plunge in many zones and also upplunge in several places.
HEINÄ CENTRAL
The deposit is a grassroots discovery, located under more than 10 m of transported glacial till cover and locally up to 40 m of glacial till.
Gold-bearing sulphide mineralisation at Heinä Central does not correspond well to any typical universally recognised deposit type, although deposits of its type are not uncommon within greenstone belts.
The deposit to have a mineralised footprint of up to 250 m (NE-SW) by 200 m (NW-SE) extending to a maximum of 240 m below surface. The deposit remains demonstrably open at depth and along strike.
Mineralisation is best described as two converging trends of mineralisation which both dip at approximately 40° to the north and northwest. The converging trends can be traced for 185 m and 175 m respectively and both have been traced 185 m down-dip from the bedrock surface, which is the extent of current drilling.
Mineralisation at Heinä Central occurs as a sulphide-rich fracture-fill and cement to a brecciated quartz-albite-carbonate vein and also as veinlets in immediately adjacent albite-altered sediments. Sulphide content ranges from a few percent up to greater than 90% in massive sulphides. Gold and copper mineralisation are however poorly correlated with the sulphide mineralisation which is dominated by pyrrhotite and to a lesser extent pyrite and chalcopyrite.
Gold is correlated with chalcopyrite mineralisation and in hand specimen chalcopyrite content is frequently a good indicator of gold mineralisation. However, the correlation is not absolute and a minor separation between the highest grade gold and copper mineralisation is observed. In addition, some gold occurs completely independently of the pyrrhotite-chalcopyrite sulphide assemblage and is more closely related to narrow sericite-silica alteration zones within predominantly sedimentary units, but this is a relatively minor contribution to the overall gold distribution.
Mineralisation remains open at depth and along strike and further drilling will help resolve apparent strike variations, folds or off-sets and possible later structural controls on gold mineralisation.