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 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.
Orivesi is located within the Proterozoic Tampere Schist Belt and represents a metamorphosed palaeo-epithermal deposit. Gold mineralisation is found in vertical pipe-like lode systems that display depth extensions ranging from tens to hundreds of metres, within a broad zone of hydrothermally altered rocks.
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. 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 first commenced.
Orivesi Gold 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. Two programs have been completed, including a high-level review of available historic airborne and ground geophysical datasets and a base of till / top of bedrock geochemical survey.
The geophysical review was undertaken by independent geophysical consultants Resource Potentials in Perth, Western Australia and was the first integrated study of geophysical datasets to be carried out across the wider Orivesi area. The review resulted in the identification of a series of geophysical anomalies east of the Orivesi mine site, through to the Koukkujärvi copper-zinc mineral occurrence. The identification of geophysical anomalism in the area west of the Orivesi mine site was limited by the lack of geophysical coverage in this area.
The base of till / top of bedrock geochemical survey was carried out over the western part of the Orivesi Mining Concession area on a nominal grid base of 50m by 50m. The results of low-level gold and multi-element analysis on till and rock samples collected have confirmed and better delineated areas of geochemical gold anomalism that were previously identified from a wider spaced geochemical survey undertaken during the early 1990’s.
The success of the new geochemical survey, together with the review of the results from the 1990’s geochemical program outside the Company’s core project holding at Orivesi, have allowed a number of gold anomalous zones north and west of the Orivesi mine to be outlined. No historic geochemical data has been located to date, for areas east of the Orivesi mine.
The anomalous gold geochemical areas west of Orivesi and the areas of geophysical anomalism east of Orivesi have now been secured by Dragon Mining, with the submission of an application for a Reservation area. The application has been successful, but is now subject to a 30 day appeal process in accordance with the Finnish Mining Act. The Reservation area will allow Company geologists opportunity to examine each of these newly identified anomalous zones during the coming field season.
Orivesi Exploration Summary
The Measured, Indicated and Inferred Mineral Resources for Orivesi as at 31 December 2019 totals 270 kt grading 5.3 g/t gold for 47 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 as at 13 November 2019.
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 Reserves and Resources 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.
Prior to the Supreme Court ruling the Company had already commenced transitioning Orivesi to Care and Maintenance status, following the exhaustion of defined Ore Reserves and had begun some rehabilitation works in the deeper parts of the mine.
The Supreme Court ruling had no material effect on production levels of the Company’s Finnish subsidiary. Ore tonnages mined from Orivesi for processing at the Vammala Plant in the Company’s Finland production plan were replaced with ore tonnages from the Company’s Kaapelinkulma and Jokisivu mines.
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.