Orivesi Gold Mine
The Orivesi Gold Mine (“Orivesi”) is located 180 kilometres north of Helsinki, immediately to the west of the Orivesi township in the Pirkanmaa Region in southern Finland. The 2,172.26 hectare project area encompasses portion of the highly prospective Tampere Schist Belt.
The Orivesi gold deposit was discovered in 1982, a result of a research project by Lohja Oy and the Department of Geology from the University of Helsinki. Outokumpu Oy (“Outokumpu”) purchased the rights to the gold deposit in 1990 and conducted technical and feasibility studies over the next four years, including two phases of test mining.
Orivesi was formally opened in 1994 and continued production through to the end of 2003, when Dragon Mining acquired the asset from Outokumpu. Dragon Mining resumed mining operations in June 2007 ceasing mining in June 2019 following the exhaustion of defined Ore Reserves. By the cessation of mining, 3.3 million tonnes of ore grading 7.1 g/t gold had been mined from the operation since mining commenced in 1992.
Geology and Mineralisation
The Orivesi Gold Mine is located within the east-west trending Proterozoic Tampere Schist Belt and represents a metamorphosed palaeo-epithermal deposit. The Tampere Schist Belt is approximately 200 kilometres long and up to 20 kilometres wide and is characterised by turbiditic metasediments and intermediate, alkaline and calc-alkaline metavolcanic rocks of mainly pyroclastic origin. Metamorphism has culminated in low-pressure, low-temperature amphibolite to transitional greenschist-amphibolite facies conditions.
Gold mineralisation is related to strongly deformed and silicified zones characterised by shearing, boudinaging, folding and quartz veining during syn- to late stage deformation forming vertical pipe-like lode systems that display depth extensions ranging from tens to hundreds of metres.
Most of the gold occurs as native gold, which has a very small grain size of generally <60µm. Gold occurs mainly along quartz grain boundaries and in late-stage fractures. A lesser amount of gold is carried by gold tellurides.
Orivesi was initially in operation between 1992 and 2003 producing 422,000 ounces of gold from a series of near vertical pipe-like lodes at Kutema down to the 720m level. Dragon Mining acquired the operation in late 2003 and recommenced mining in June 2007 initially on remnant mineralisation associated with the Kutema lode system above the 720m level. Two of the five principal lodes at Kutema continued below the historical extent of the decline at the 720m level and this area was the subject of a program of staged development and production stoping down to the 1205m level between January 2011 and January 2018. Mining from the Sarvisuo lodes, 300 metres east of Kutema commenced in April 2008 and has been conducted from the 240m to the 620m level, as well as between the 360m and 400m levels and the 650m and 710m levels in the Sarvisuo West area.
Mining at Orivesi ceased in June 2019, with Dragon Mining commencing work on closure of the mine.
The Company maintains a contiguous exploration tenement holding at Orivesi, fully encompassing the hydrothermally altered domain that hosts the two known lode systems, Kutema and Sarvisuo.
Following the cessation of mining at Orivesi during 2019, the Company embarked on a campaign of early-stage exploration to evaluate the merit of the Company’s core project holding, in areas away from the Orivesi mine. A series of programs have been completed, including a high-level review of available historic airborne and ground geophysical datasets, a base of till / top of bedrock geochemical survey and a reconnaissance diamond core drilling campaign across areas of identified geochemical and geophysical anomalism on the Orivesi Mining Concession.
Resources and Reserves
The Measured, Indicated and Inferred Mineral Resources for Orivesi as at 31 December 2019 totals 270 kt grading 5.3 g/t gold for 46 kozs. The Mineral Resource represents material from the Kutema and Sarvisuo lode systems. The Mineral Resources are reported at a 2.6 g/t gold cut-off, which is based on operating costs, mining and processing recoveries from Orivesi actuals and a gold price of US$1,770 per troy ounce that has been extrapolated for the potential economic extraction of the resource at a level approximating 120% of the short term consensus forecast gold price of US$1,475 per ounce.
No Ore Reserves are reported for the Orivesi Gold Mine.
For further information on the Ore Reserves and Mineral Resources for the Orivesi Gold Mine refer to the Resources and Reserves page.
On the 6 June 2019, the Supreme Administrative Court of Finland (“Supreme Court”) issued a ruling in relation to the appeals lodged concerning the Environmental Permit for Orivesi.
The Supreme Court upheld the decision by the Western and Inland Finland Regional State Administrative Office (“AVI”) to not grant the new Environmental Permit for Orivesi, the application for which was originally lodged in 2010. Both Dragon Mining and the Centre for Economic Development, Transport and the Environment of Pirkanmaa (“ELY”), which oversees the operation, had appealed the AVI decision initially to the Vaasa Administrative Court and then the Supreme Court.
The Company retains the right to undertake further exploration at Orivesi, with the Mining Concession and surrounding Exploration Permits remaining legally valid. Dragon Mining can apply for a new Environmental Permit if further exploration in the Orivesi project area supports the recommencement of mining.