The Jundee Operation are located in the Northern Goldfields region of Western Australia around 45 kilometres northeast of Wiluna and approximately 520 kilometres north of Kalgoorlie. Production commenced in 1995 from a complex of open pits (now ceased), and in 1997 from two underground mines. Ore is currently sourced only from the underground mining operations. Jundee was acquired by Northern Star in 2014.
GEOLOGY & MINERALISATION
Jundee is an Archean lode-gold deposit located in the northern Yandal greenstone belt. The local greenstone succession is dominated by mafic-ultramafic rocks and dolerite sills. The Jundee mine sequence comprises two tholeiitic basalt units (Fisher and Lyons Basalts), separated by a sedimentary sequence that has been intruded by a suite of differentiated dolerite sills. The entire mine sequence is cut by dacitic porphyry, porphyritic granodiorite and lamprophyre intrusions.
Gold distribution is controlled by a brittle fault-fracture system preferentially developed in dolerite and basalt and, to a lesser extent, in felsic-intermediate porphyry. Individual ore lenses are typically tabular in geometry, narrow and highly discontinuous, and occur in multiple orientations. Proximal alteration is characterised by a quartz-sericite-ankerite-sulphide (pyrite ± arsenopyrite ± chalcopyrite) assemblage.
Currently all ore is sourced from Jundee underground operations which yield ~1.8M tonnes ore each year. There are three underground portals which provide access to the various underground lode structures – Barton, Gateway and Invicta portals. The Barton portal contains three actively working ore bodies (Nim3, Lyons and Westside) with Invicta consisting of the Invicta (remnants), Cardassian and Deakin ore bodies, while the Gateway and Gringotts ore bodies are mined from the Gateway portal. The underground mining is being carried out by an up-hole long-hole open stoping sequence as its primary method. No backfill or paste is used.
The Jundee processing circuit is a conventional CIL plant with a hard rock processing capacity of approximately 3.0M tonnes per year. The process consists of a single toggle overhead eccentric swing jaw crusher followed by a SAG and Ball milling circuit incorporating gravity recovery and CIP process achieving 92% recoveries.