There’s much more life to Far East’s Wonogiri mine as talk turns to historic global copper, gold prices
Far East Gold has consultants Mining One back on board to lead a new scoping study at its massive 1.15Moz Wonogiri project in Indonesia.
Amid historically high gold and copper prices, the project and its 1.15Moz gold equivalent Randu Kuning copper-gold deposit in south central Java was last picked apart by Augur Resources more than eight years ago – back when copper and gold were literally being given away at just US$5500/t and US$1350/oz respectively.
Those days are well behind, with the twin commodities coming to play differing but highly central roles in the new global economy.
Copper has surged to be trading at around US$9400/t and the safe haven yellow metal pays more than US$1850/oz, although both are thought to have enormous upside still in both volatile and transitioning markets.
Mining One, which previously provided Far East Gold (ASX:FEG) a pit optimisation study for Wonogiri containing a high-level open pit and potential underground study for Randu Kuning, is expected to deliver the results for release by late July 2022.
FEG has started several major streams of work to complement the start of the scoping study, including met test work on porphyry and epithermal core samples as well as remodelling and reinterpretation of geophysical data at Wonogiri.
That reinterpretation has identified the potential to increase the JORC 2012 resource at Randu Kuning, which includes 996,000oz of gold (53% in the higher Measured and Indicated categories) and 190Mlb of copper (43% Measured and Indicated).
Previous drilling included almost 20,000m of diamond drilling largely within the Randu Kuning porphyry deposit, including intersections of wide mineralized zones like 135.5m at 1.28g/t gold and 0.2% copper from 44.5m and 222m at 0.95g/t Au and 0.2% Cu.
The resource has potential to grow at deeper levels. Drill hole IWG-02 for instance returned 37m at 1.77g/t Au and 0.23% Cu from 458m downhole remaining open at depth.
Interpretation of the model generated by historic ground magnetic and IP data by FEG has also shown three new potential porphyry drill targets to the southeast of Randu Kuning.
The northwest trend meanwhile is interpreted as a possible intrusive corridor and is thought to have similar structural features that control the porphyry and epithermal mineralization at the Trenggalek and Tujuh Bikit deposits.
The comparison to Tujuh Bikit is absolutely fascinating – given its massive scale. This is a hole boasting 30.1Moz of gold and 18.9 billion pounds of copper.
The hits keep coming. Previous scout drilling also identified potential porphyry and epithermal discoveries at Jangglengan and Kepil, with results of Jangglengan as solid as 3m at 7.8g/t gold, 9g/t silver, 0.29% copper and 0.38% zinc from 70m (including 1m at 15.9g/t Au and 20.7g/t Ag) and 7m at 2.64g/t Au and 1/7g/t Ag from 120m.
Gold and copper recovery test work has begun on porphyry samples from Wonogiri with head grades of 0.8-1.7g/t gold and 0.11-0.21% copper and epithermal samples ranging from 10g/t gold and 6g/t silver and 0.58g/t gold and 8.5g/t silver.
Overall grade recoveries had ranged from 90-91%, with initial results from porphyry samples returning 35-51% of the contained gold by simple gravity alone, with a further 83-85% of gold in gravity tailings able to be recovered using the conventional carbon-in-leach technique.
Positive results have also come from recent test work which showed cyanide usage could be reduced by up to 1.4kg/t, while environmental test work has shown tailings from dry stacking of leach residue to be non-acid forming.
Gold leaching test work on epithermal gold samples from Wonogiri using gravity concentrate and CIL processing has now begun.
On the ground, Far East’s team are seriously looking forward to those results as well.
FEG believes resource delineation within areas of epithermal mineralisation could very well extend the project’s potential mine life.
This article was developed in collaboration with Far East Gold, a Stockhead advertiser at the time of publishing.
This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.