The Empire Mine is a historic copper mine, being brought back into production via phased development. Phoenix is seeking to commence initial open-pit production by 2020, targeting 7,000t per annum of copper cathode.
An Established Resource
The Empire Mine has an all-category JORC complaint resource of 12.8mt at 0.53% Cu for 68,200t contained copper amenable to open pit mining and processing using an SX-EW heap leach.
Polymetallic mineralisation is hosted along a 150m wide sinuous belt extending for more than 2,500m in length. The mineralisation intersected is oxidised copper from surface to a vertical depth of approximately 120m, with sulphide copper mineralisation dominating below that depth.
Crucially, it is estimated that only 5% of the potential ore system has been explored to date and accordingly there is strong opportunity to significantly increase the resource:
The Project has an exploration target of between 3.4 to 6.7 million tonnes (derived from historic data), grading 0.34% to 0.50% copper for 11,560 to 33,500 tonnes additional contained copper
The oxide resource remains open along strike giving significant opportunity to expand the current copper oxide resource
The higher-grade sulphide zone, which underlies the oxide zone, is open in all directions and remains virtually unexplored. The current resource does not include this sulphide zone where intercepts of up to 11.4% Cu have been returned
There is significant potential for the economic extraction of additional metals, including gold, silver, zinc and tungsten
History of the mine
Mineralisation was first discovered at the mine in 1884, when small scale mining quickly commenced and continued through to the 1940s. From 1901 to 1942, it produced 694,000 tonnes with recovered grades of 3.64% Cu, 1.64 g/t Au and 53.8g/t Ag from underground workings. Later shipments included significant tungsten grades highlighting the potential that the Empire Mine could access tungsten ore at depth.
Since the mine closure, exploration has been primarily focused on the surface copper oxide mineralisation, which is amenable to SX-EW cathode copper recovery; a total of 220 exploration shallow drill holes were completed between 1964 and 1997 by various exploration companies. Nonetheless, data collected also provided insight into the enriched secondary sulphide copper zone (supergene zone), with intersections recovered ranging from 1.2% Cu to 11.4% Cu.
Phoenix acquired operational control in 2016 and is focussed on rapidly advancing the mine into production.
Route to production
Phoenix intends to deliver production at the Empire Mine in two phases to minimise upfront capital requirement and lead-time to cash flow.
- Focussed on delivering an open pit copper operation to mine the oxide resource at an initial rate of 7,000 tonnes of cathode copper per year with a minimum life of mine of 10 years
- Extend the life of mine and capitalise on the significant potential presented by the sulphide mineralisation via an underground operation
Accordingly, whilst the Company continues to review the near surface copper oxide potential of the mine it will seek to better understand and develop a resource across the supergene enriched and sulphide copper potential.
The Empire Mine is located in the Alder Creek Mining District in Custer County, Central Idaho, USA, approximately 5.5km southwest of the town of Mackay. The project is accessible from Mackay via a well-maintained all-weather gravel road.
miles to Idaho Falls Regional Airport
Custer County population
Miles to Twin Falls Regional Airport
Miles to Boise International Airport