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Pyhasalmi |
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Finland |
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Cu Zn Ag Pb
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Pyhäsalmi volcanic hosted copper-zinc-silver-gold-pyrite deposit is located 4 km southeast of the town of Pyhäjärvi, on Lake Pyhäjärvi, in Finland, ~400 km north to NNE of Helsinki (#Location: 63° 39' 34"N, 26° 2' 31"E).
Pyhäsalmi was discovered in 1958 and commenced operations from an open pit under the ownership of Outokumpu Oy in 1962 based on a resource estimate of 33.4 Mt. The mine went underground in 1967 and by 1979, mining ceased from the open pit. Additional deep ore was discovered in 1996. The operation was sold to Inmet Mining in 2002, and was acquired by First Quantum Minerals in 2013 via its purchase of Innmet. Mining activities are projected to end in 2021.
The deposit is comprise steep elongate rod to tabular bodies of massive and disseminated sulphide ores within the axis of a sheath fold in a strongly altered sequence of deformed and metamorphosed Palaeoproterozoic (1.90 to 1.93 Ga) mafic and felsic volcanics and carbonates. The host unit is the Ruotanen Formation, composed of altered felsic tuffs, volcanic breccias, quartz-porphyries and unaltered felsic volcanics which belong to the Pyhasalmi bimodal volcanic complex. The enveloping alteration zone is at >4 km in strike length and 1 km at its widest. The alteration of the felsitic volcanics is characterised by a sericitic and cordieritic dominated mineralogy, whilst mafic volcanics are altered to a cordierite, anthophyllite and garnet dominating assemblage. The Deep Ore is hosted by less altered felsic volcanics. Metamorphism of the hydrothermally altered host rocks has produced the distinctive cordierite-orthoamphibole lithologies.
The ore assemblage includes pyrite, sphalerite, chalcopyrite ± pyrrhotite in a gangue of carbonates and baryte and an alteration suite of sericite (potassic alteration) and cordierite-anthophyllite (representing Mg-metasomatism).
The coarse by-product pyrite (recrystallised by the metamorphism) concentrate makes the deposit economic.
Production, reserve and resource figures inlcude:
25.2 Mt @ 2.66% Zn, 0.06% Pb, 0.76% Cu, 14 g/t Ag (1993 prior to the discovery of the Deep Ore),
75.5 Mt @ 1.9% Zn, 0.9% Cu, 0.4 g/t Au, 38.6% S (2000).
Production to 2020 has amounted to around 60 Mt of ore.
Production guidance for the year 2020 is 3000 t of copper, 1000 t of zinc, 0.06 t of gold and 0.45 Mt of pyrite.
Mineral Resources and Ore Reserves at 31 December, 2018 were (First Quantum Resources and Reserves website page):
Measured + Indicated Resources - 5.597 Mt @ 0.53% Cu, 0.34% Zn, 0.40 g/t Au, 13 g/t Ag, 41.81% S;
Proved + Probable Reserves - 1.1 Mt @ 0.59% Cu, 0.27% Zn, 0.40 g/t Au, 13 g/t Ag, 43.11% S.
Reserves are included within Resources.
For detail consult the references listed below.
The most recent source geological information used to prepare this decription was dated: 1994.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
Pyhasalmi
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Mikkola A K, Rouhunkoski P 1980 - The copper deposits and their metallogeny in southern Finland: in Jankovic S, Sillitoe R H (Eds.) 1980 European Copper Deposits Proceedings of an International Symposium held at Bor, Yugoslavia, 18Ð22 September 1979. Belgrade University, pp 180-187
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Roberts M D, Oliver N H S, Fairclough M C, Holtta P S, Lahtinen R 2003 - Geochemical and Oxygen isotope signature of sea-floor alteration associated with a polydeformed and highly metamorphosed massive sulfide deposit, Ruostesuo, central Finland: in Econ. Geol. v98 pp 535-556
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Weihed P, Arndt N, Billstrom K, Duchesne J C, Eilu P, Martinsson O, Papunen H and Lahtinen R 2005 - Precambrian geodynamics and ore formation: The Fennoscandian Shield : in Ore Geology Reviews v27 pp 273-322
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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