Kingston Resources released a maiden Pre-Feasibility Study for the Misima Project in November 2020. The PFS confirmed the potential to develop a technically robust, large-scale, long-life, low-cost operation delivering gold production of 130,000oz per annum at forecast life-of-mine (LOM) all-in sustaining costs (AISC) of A$1,159/oz over a forecast 17-year mine life.
The PFS is based on the redevelopment of the brownfields site of the former Misima gold mine, which was operated previously as a successful 5.5Mtpa Carbon-in-Leach (CIL) open pit operation by Placer Pacific, producing 230kozpa over a 15-year production history.
Kingston plans to leverage off this strong production history and construct a new 5.5Mtpa CIL treatment facility and modern infrastructure on the footprint of the historic mine, establishing a new standalone, long-life gold mining and processing operation underpinned by two major ore sources – a cut-back of the existing Umuna open pit and an expansion of the existing pit at Ewatinona in the Quartz Mountain area.
Alongside the PFS, Kingston reported a maiden JORC Probable Ore Reserve of 48.3Mt @ 0.9g/t for 1.35Moz, which underpins the large scale, long-life Misima Gold Project.
The scale and quality of the Mineral Resource and Ore Reserve, together with the brownfields nature of the Misima Project, the extensive mining and processing history, the relative softness of the ore and simplicity of the process flowsheet all give Kingston a high degree of confidence in the technical and commercial viability of the Project as the foundation for a long-term Asia-Pacific gold operation.
The Misima Gold Project is an exploration and development asset with significant scale underpinned by a 3.6Moz gold Resource and a 1.35Moz gold Reserve. It also hosts a number of exciting exploration targets. Kingston is the first company to focus on recommencing gold production at Misima since Placer Dome ceased its operation in 2004, having successfully produced 3.7Moz over a 15 year mine-life.
Misima Island is located 625km east of Port Moresby in the Solomon Sea. Gold was discovered on the island in 1888 with small scale underground mining continuing until WWII. Placer Dome Inc (Placer) commenced exploration in 1977, with production beginning in 1989. Misima was operated as an open pit gold mine from 1989 to 2004, producing 3.8Moz at an average cost of US$218/oz.
Further opportunities – Exploration strategy
Kingston’s drilling has been focused on delivering to its strategy of identifying near-surface ounces to deliver ore feed for the early years of operation into the Misima mine plan while access to the main Umuna orebody was re-established via a pit cut-back.
This led to the successful identification of Ewatinona as a 200koz starter pit for inclusion in the PFS.
Kingston has also identified a number of further target areas to continue to deliver on this strategy:
- Kulumalia – Targeting conversion of near-surface ounces from Inferred to Indicated and potential Reserve status.
- Umuna East – Further drilling at Umuna East will target the expansion and upgrade of the Inferred Resource in this area. As with Kulumalia, Umuna East is a possible target for adding higher grade feed to early years’ production;
- Kobel/Maika – These are historical Placer starter pits located between Umuna and Ewatinona that have had little follow up exploration. Following the successful brownfield program at Ewatinona that resulted in its inclusion as a starter pit in the PFS, Kingston now intends to replicate this strategy at Kobel and Maika.
The Misima Gold Project comprises two main deposits at Umuna and Ewatinona, and multiple reconnaissance exploration targets along and adjacent to the 12km strike length of the Umuna Fault Corridor that hosts the historical Umuna deposit, and Quartz Mountain area that hosts the Ewatinona deposit.
Misima Island forms part of the Louisiade Archipelago which is a continuation of the Papuan Fold Belt of the Papuan Peninsula offshore eastwards through the Papuan Plateau. The oldest rocks on Misima are Cretaceous to Paleogene metamorphic rocks, which can be subdivided into the western Awaibi Association and the younger overthrust eastern Sisa Association that is host to the gold and copper mineralization. The two associations are separated by an original thrust fault with later extensional activation.
Mineralisation deposit style on Misima Island is best described as low sulphidation carbonate base-metal epithermal due to the vein characteristics, the dominance of silver zinc lead gold copper and manganese geochemistry as well as complex alteration styles and geometry, and strong association with precursor porphyry Cu-Au style alteration.