Kuhmo Nickel Project
The Kuhmo Nickel Joint Venture (“Kuhmo Project”) contains a number of Archean komatiite-hosted nickel sulphide deposits within the Karelian Craton of eastern Finland. The Kuhmo Project is 95% owned by Altona and is a joint venture with Dragon Mining Oy (“Dragon”). The project has strategic landholding on and adjacent to known five deposits between the regional centres of Kuusamo in the north and Kuhmo 200 kilometre to the south.
The Karelian Craton is a typical Archean granite-greenstone terrain with greenstone belts comprised of ultramafic, mafic and felsic volcanic rocks and minor sedimentary rocks. The ultramafic rocks host massive and disseminated nickel sulphide mineralisation similar to well endowed Archean greenstones in Australia and Canada.
The area has undergone sporadic exploration by Outokumpu and by The Geological Survey of Finland (“GTK”) since initial discoveries of outcropping massive sulphide mineralisation were made in the 1960’s. There has been no mining to date.
Comparison of the Kuhmo Project with other highly endowed nickel fields highlights that these better explored terrains typically host clusters of deposits within which new deposits have been discovered over time. This clustered nature is characteristic of komatiite hosted nickel sulphide deposits, suggesting that the deposits discovered to date in Finland are a compelling indicator of the high potential for discovery of further mineralisation.
Vaara Region
The Vaara region is located within the northern portion of the Suomussalmi Greenstone Belt and consists of a north to north-northeast striking sequence of mafic, ultramafic and felsic rocks. It contains several large (up to 3 kilometres x 0.5 kilometres) serpentinite (ex-olivine cumulate) lenses.
The lenses are developed within a complex and poorly known sequence of komatiite flow units, mafic rocks and discontinuous meta-sedimentary units over approximately 15 kilometres of strike dipping steeply to the east. Nickel mineralisation has been discovered in drill holes or in outcrop in 3 lenses and in footwall komatiite units west of the Vaara lens.
Vaara Deposit
At Vaara, disseminated nickel sulphide mineralisation is developed within a serpentinised olivine ortho-mesocumulate with MgO content varying between 40-42.5%. Several southwest-northeast trending serpentinite and associated chlorite-amphibole rock units can be identified within the Vaara komatiitic complex. These ultramafic rocks are enveloped by felsic and mafic volcanic rocks and related metasedimentary rocks.
The deposit occurs within a north-south trending zone of mineralisation 450 metres long. The thickness of the deposit varies between two to three metres at its northern part and up to 60 metres thick at the south. The vertical depth of the known deposit is limited by drilling from 50 metres in the north to 170 metres in the south. In general, the deposit remains open at depth and the average nickel grade is between 0.3% and 0.6% nickel, with a highest value being 1.99% nickel. The nickel tenor is high being 20-50%.
Results of the drilling included:
- Longest intercept: SMS/SK-56 : 43.00 metres at 0.43% nickel and 0.31 g/t palladium + platinum
- Highest grades: SMS/SK-57: 1.00 metres at 1.44% nickel and 1.62 g/t palladium + platinum
- Best intercept R656, 10 metres at 1.15 % nickel, 0.15 % copper, 0.023 % cobalt and 0.69ppm palladium. Platinum has not been assayed.
Kauniinlampi Deposits
The Kauniinlampi ultramafic lens is between 200 and 500 metres wide, 2,300 to 3,400 metres long and hosts three nickel occurrences.
Kauniinlampi north where nickel is associated with a north-west trending, north-east dipping fault. This nickel occurrence occurs as fine grained sulphide dissemination in a sheared serpentinite. The occurrence is up to 20 metres thick and 100 metres long and nickel content varies between 0.2%-1.0%. The principal nickel mineral is pentlandite with lesser heazlewoodite.
The GTK intersected the Kauniinlampi North occurrence with 11 holes at shallow depths, 40 – 120 metres vertical depth and remains open north, south and downwards.
Peura-aho- Heitaharju Region
The Peura-aho prospect is located approximately 20 kilometres south of Vaaraand is related to a large scale anticline plunging steeply to the north-east. The sequence hosting the deposit comprises a footwall of porphyritic felsic schist, a serpentinite unit and hangingwall mafic unit that includes narrow quartzo-feldspathic and carbonaceous schist horizons. The nickel sulphide mineralisation occurs as disseminated sulphides within the serpentinite unit and as massive sulphides within the footwall quartzo-feldspathic schist.
Peura-aho Deposit
Peura-aho was discovered by prospector samples of massive nickel and copper sulphides in the early 1960`s. Outokumpu completed an exploration program in 1961-63. Which led to the discovery of Peura-aho and the nearby (4 kilometres) Hietaharju nickel-copper deposits.
The massive sulphide deposit is exposed at surface as an east-west trending gossan over approximately 50 metres.
Altona has drilled total of 52 diamond drill holes in three phases at the Peura-aho prospect totalling 4,343 metres.
Exploration at the Peura-aho prospect resulted in:
- Significant improvement on understanding geology, structure and mineralisaiton types resulting identification of four types of nickel mineralisaiton: disseminated, massive contact and talc-carbonate rock hosted (SW mineralisation)
- Longest intercepts:
- Disseminated sulphides:SMS/PA-14: 19.00 metres at 0.49% nickel, 0.19% copper and 0.82ppm palladium+ platinum
- Massive sulphides: SMA/PA-38: 57.60 metres at 1.32& nickel, 0.56% copper and 1.23pp palladium + platinum
- Contact type sulphides: SMS/PA-35: 9.61 metres at 0.90% nickel, 0.48% copper and 1.09ppm palladium + platinum
- SW mineralisation: SMS/PA:3.15 metres at 2.74% nickel, 1.18% copper and 4.43 palladium + platinum
- Highest grades: SMS/PA-30: 0.32 metres at 3.23% nickel, 1.13% copper and 4.47ppm palladium + platinum
Hietaharju Deposit
The Hietaharju deposit is associated with a north-northeast trending talc-carbonate altered ultramafic cumulate body with associated multiple and discontinuous zones of chlorite-amphibole rocks. The ultramafic body is approximately one kilometre long and up to 100 metres thick, dipping between 70º east and vertical. The ultramafic is located within a sequence of near vertical to overturned quartzo-feldspathic schists in the east and pyritic schists within komatiitic basalts in the stratigraphic hanging wall to the west.
The deposit occurs as lenses of massive sulphide breccia and fine-grained disseminated sulphide hosted by a talc-carbonate rock and also within chlorite-amphibole rock unit within the footwall contact.
Massive sulphides comprise pyrrhotite and pentlandite with some chalcopyrite. The southern part of the deposit usually occurs within chlorite-amphibole rock and close to the eastern (footwall) contact of the ultramafic unit. The northern part of the deposit is central within the talc-carbonate rock away from the interpreted footwall contact.
The deposit is approximately 200 metres long and the thickness varies from less than 0.5 metre thick massive sulphide veins up to 10 metre thick units of disseminated and massive sulphide. High platinum group element values have been reported in drilling results. The tenor of the deposit is 2-5% nickel and platinum+palladium is 0.5 – 5ppm.
Sika-aho Deposit
The Sika-aho nickel deposit is hosted by sheared felsic, mafic, ultramafic rocks and minor graphitic schist within the western edge of the north-northeast trending Tammasuo Shear Zone.
The Tammasuo Shear Zone separates a sequence of mafic and minor ultramafic units in the east from a regional antiform comprising mafic rock overlain by a thick ultramafic sill and a relatively thick komatiite sequence. To the west of Sika-aho the local geology consists of a multiply deformed synform of komatiite and basalt.
The nickel deposit is located a few metres west from talc-carbonate altered komatiitic cumulates and comprises a one to nine metre wide zone of massive sulphides developed over approximately 80 metres of strike length. Disseminated and sheared sulphides continue for over an additional 150 metres to the north-northeast. This occurrence extends at least 150 metres below surface with a dip of 85º to the south-east.
The host rock is often quartz rich and partially carbonated chlorite schist and has been interpreted as originating from the highly altered a komatiitic lava flow of pyroxenite composition. The high nickel-copper ratio (>15:1) of mineralisation is consistent with a primary magmatic origin. Nickel tenor is 5-20% for nickel mineralisation grading over 0.5% and has wider variation from 3% up to 55% for lower grade (0.3-0.5% nickel) mineralisation. The principal sulphide minerals are pyrrhotite and pentlandite.
The fact that the deposit is situated along, or near, the contact of ultramafic rocks indicates the possibility of Kambalda style mineralisation but the strong structural correlation suggests mobilisation of the occurrence from the original position within the shear zone.
The best intercepts at Sika-aho were encountered in holes R306 and R319, drilled by the GTK in 1994 – 1997, returned 7 metres at 1.26% nickel and 3.74% sulphur and 8 metres at 1.16% nickel and 4.86% sulphur respectively.
GTK completed a polygonal resource estimate based on a vertical cross section in 1998 which quotes 175,000 tonnes at 0.7% nickel down to 300 metres below surface (GTK, 1998, reference 13).
Arola Deposit
The Arola deposit is located immediately west of the town site of Harmankyla and is located within a north-south trending greenstone belt dominated by mafic volcanic rocks and ultramafic units.
The belt is less than two kilometres wide in this area; however it widens to five to eight kilometres in the north and south. The local geology comprises a sequence of amphibolite, schistose sedimentary rocks including graphitic schist, serpentinite and talc-carbonate altered ultramafic rocks. Bedding and schistosity are almost vertical and the stratigraphic bottom within the mineralised area is interpreted to be towards the east.
The deposit is hosted by sheared and quartz-carbonate-chlorite altered Cr-basalt units juxtaposed against metasedimentary rocks, including greywacke and phyllite, along the eastern contact. These sediments are the source of the electromagnetic anomaly in the area that can be followed approximately one kilometre north and south from the deposit. Unaltered Cr-basalts, which are considered as part of the Archean komatiitic sequence are located on the western side of the mineralised chlorite schist. The deposit is interpreted as mobilised but the origin is probably komatiitic.
The Arola deposit can be divided into three distinct zones comprising discontinuous lenses over 400 metres of strike length and 400 metres below surface. Two of the zones are almost parallel to the orientation and shearing of the host rock and they are about 40 metres apart from each other. The third mineralised zone cross cuts the schistosity at an angle of approximately 35º. All mineralised zones are composed of several discontinuous lenses. The more coherent lenses are interpreted to plunge approximately 40° to the north.
The main sulphide minerals are pyrrhotite, pyrite and pentlandite. Nickel content is commonly less than 1%; the highest grade assayed is 5.72% nickel. Copper grade is low, usually less than 0.1% and the highest value is 0.4% copper. The content of platinum group elements is very low, <0.04ppm. Nickel tenor varies quite a lot from 2% up to 25%, the average being 10-15%.
