Pyhäsalmi Mine

Name
Owner
Mining concession number
Discovery
Mining
Host rock
Genetic type
Ore tonnage mined (end-2011)
Grade (2011)
Production (end-2011)
Reserves (proven+probable, end-2011)
Resources (measured 2011)
Pyhäsalmi
Inmet Mining Co (2002-)
1317
1958
Open pit 1962-1976; underground 1967-
Felsic metavolcanic rocks
VMS 
49.477 Mt
1.1 % Cu, 2.6 % Zn, 40 % S, 0.35 g/t Au, 13 g/t Ag
0.55 Mt Cu, 1.3 Mt Zn, 23 Mt pyrite 
9.137 Mt @ 1.1 % Cu, 2.0 % Zn, 0.4 g/t Au, 14 g/t Ag, 41 % S 
7.168 Mt @ 0.6 % Cu, 0.5 % Zn, 44 % S
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Pyhäsalmi mine site

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Location and infrasturcure
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Resources 2000

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Pyhäsalmi regional geology
Pyhäsalmi is the oldest operating metal mine in Finland and the deepest in Europe. It is a Zn-Cu VMS-deposit with hydrothermally altered host rocks subsequently being metamorphosed, deformed, recrystallised and partially remobilised under amphibolite facies conditions. The ore is hosted by felsic pyroclastic rocks and quartz-porphyries. Mafic volcanic rocks in the area are coarse-grained tuff breccias and lavas, the latter containing pillowed units. Mafic and felsic dykes are common. The volcanic host rocks belong to the Palaeoproterozoic (ca. 1.92 Ga) Svecofennian island arc succession near the margin of the Archaean Karelian craton.

The composition of the Pyhäsalmi ore varies both horizontally and vertically. To the depth of about 1000 m, sphalerite is concentrated in the central part and chalcopyrite near the outer margins of the ore. In deeper levels, there is massive pyrite (low Cu, Zn) in the centre, which is enveloped by chalcopyrite ore and further outwards by Zn ore. The highest barite contents are generally encountered in the sphalerite-rich areas. The ore is a massive pyrite ore with 70% sulphides. The sphalerite-rich ore is in some places finely banded and thin pyrite-porphyritic bands are common. A pyrite dissemination, which in some places has a breccia structure, exists around the massive ore. Pyrrhotite has replaced pyrite in the southern end of the ore.
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3D -views of the deposit

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Typical massive ore
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Deep ore: exploration and inventory drilling
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Deep ore and immediate
wallrock

Since 1996 the mine has been deepened and has now a ramp down to 1441 m level and two shafts. The main production level will be the level +1400. The new shaft connects the surface to the level +1441. This means an extension of about ten years to Pyhäsalmi's lifetime. Metal contents are slightly higher in the deeper parts of the mine. Zinc concentrates are transported to the Boliden's zinc plant at Kokkola, and copper concentrates to the Harjavalta copper smelter, both in Finland. Pyrite concentrates are sold in Finland and on the world market. The mine has a personnel of about 290 people.



 

Detailed description Publications Inmet Mining Co