The Gruyere deposit is one of the most significant of its kind in the Yamarna Belt. All Images: Gold Road Resources.
By Cameron Drummond
COMPLETED in 2010, a study by the Geological Survey of WA suggested the Yamarna Belt shared geological similarities with the Kalgoorlie Terrane greenstone rocks, and studies by previous explorers such as Ausgold supported that claim.
Gold Road Resources’s 5000 square kilometres of tenements in the Yamarna Belt already contain a number of discoveries dating back to 2009 when the company made its first find, Central Bore.
Central Bore is contained within Gold Road’s North Yamarna tenements, with a JORC 2012 resource of 180,000 ounces (oz) of gold grading at 0.9 grams per tonne (g/t), including the high grade Imperial Shoot deposit containing a resource of 112,000oz grading at 22.7g/t.
While the deposit had not been included in the Gruyere feasibility study, Gold Road said there was potential to process ore from the deposit through the proposed Gruyere plant facility.
It wasn’t until the discovery of the Gruyere deposit that the Yamarna Belt started proving itself as the next big thing in the region since the 2005 discovery of AngloGold Ashanti’s Tropicana.
Gruyere, discovered in October 2013, is 200km east of Laverton in the WA Goldfields region.
The company’s exploration strategy was to divide its tenements into ‘gold camp scale targets’, between 15km and 25km in strike length.
“We flew aeromagnetic surveys across the tenements, looked at the old gravity surveys and employed some of the big geological thinkers from WA to come in and interpret those surveys and they came up with what they called ‘camp scale targets’,” Mr Murray said.
“This led to us reducing the area of focused exploration by 80 per cent from 5000sqkm down to roughly 1000sqkm, and we ended up generating 10 of these camp scale targets, each of them between 80sqkm and 120sqkm.”
The first camp scale target Gold Road unearthed contained the monster Gruyere deposit and the YAM14 deposit.
Gruyere and YAM14 were discovered 9km apart on the same trend, and exhibited two different mineralisation types not seen previously in the Yamarna Belt.
Within 10 months, the company had defined Gruyere as a significant gold deposit with a maiden mineral resource of 96.96 million tonnes (mt) grading at 1.23g/t for 3.8moz) of gold.
By October 2016, Gold Road completed a bankable feasibility study that confirmed Gruyere as one of the longest life, lowest cost undeveloped gold deposits in the world, containing 6.16moz of gold to support the production of 270,000ozpa over a life of mine of 13 years.
Development of the Gruyere project will be based on a single large open pit mine with a conventional SAG/ball mill circuit, gravity carbon-in-leach processing plant with a throughput of 7.5mtpa of fresh ore and up to 8.8mtpa of oxide ore.
A bankable feasibility study showed that Gruyere was a significant gold deposit, with an initial mine life of 13 years.
In November 2016, Gold Road formed a joint venture (JV) with South African miner Gold Fields to de-risk and fast-track the development of its Gruyere project.
It agreed to split the project down the middle, selling Gold Fields 50 per cent for a consideration of $350 million cash and an uncapped 1.5 per cent net smelter return royalty after the production of 2moz.
Gold Road managing director Ian Murray said the company was pleased to have chosen Gold Fields as its JV partner.
“The highly experienced team that we have established over the past 18 months will be the team that will develop the Gruyere gold project under the guidance and leadership of Gold Fields,” Mr Murray said.
Environmental approvals were granted in December last year, with final mining and construction approvals received in February.
Mr Murray said that achieving environmental approval was an important milestone and cleared the path for obtaining the final approvals for the project, all of which were submitted mid-January.
The first 300 rooms of accommodation for the project’s village were completed in January, with work to dismantle, relocate and install the second lot of 300 rooms commencing in February for completion during the June quarter.
“Detailed engineering for the airstrip, access roads, tailings storage facility and Anne Beadell bore field are well advanced and will be completed by the end of the March 2017 quarter,” the company said in a statement.
Gold Road also said it was in the final stages of evaluating tender submissions for works contracts including the engineering, procurement and construction (EPC) contract for the process plant and associated infrastructure.
On 15 February, the Gruyere project received its final approvals from the WA Department of Mines and Petroleum.
“Approval of the project management plan, mining proposal and mine closure plan is another important milestone in the development pathway for Gruyere, and importantly it was completed according to the project schedule,” Mr Murray said.
“Once we award the EPC, bulk earthworks and gas contracts, full scale construction will start this month.
“We are expecting first gold from Gruyere in late 2018, with the ramp up to up to full scale production to occur in 2019.”
Exploration at Gold Road’s prospects along the Yamarna Belt continued through the second half of 2016, with RC drilling at the Ibanez prospect 55km north-west of Gruyere, as well as the Santana and Satriani prospects 35km south-west of the company’s flagship project.
Looking into 2017, Gold Road is now fully funded to develop Gruyere and accelerate exploration activities across its 100 per cent owned North Yamarna and 50 per cent owned South Yamarna tenements.
The company announced it would allocate $22m for exploration in the Goldfields region; an effective doubling of the company’s 2016 exploration budget.
“The funding we have available following completion of the Gruyere JV transaction allows us to accelerate our geological evaluation of the Yamarna Belt,” Gold Road executive director exploration and growth Justin Osborne said.
“In 2017, we plan to test multiple targets identified over the last three years across the North Yamarna tenements and are anticipating an aggressive drilling program for the Gruyere JV which will be targeting the potential underground extension to the current open pit mineral resource.”
Mr Murray said Gold Road’s exploration budget was currently one of the biggest greenfields gold exploration budgets in the world.
Between $12m and $15m would be used for exploration at North Yamarna, $5m below the Gruyere pit, and a further $2m to be used for drilling at South Yamarna with 50:50 JV partner Sumitomo Metal Mining Oceania.
“We will be doing further RC and diamond drilling to confirm the size and scale of our discoveries at North Yamarna, testing below the Gruyere pit, to increase the Attila and Alaric reserves; and undertaking regional aircore exploration at South Yamarna to define targets for the future,” he said.