Jundee

The Jundee mine is 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.

History

The Wiluna area was first explored by Lawrence Wells in 1892. Gold was discovered in the area in 1896, and within a few months there were over 300 prospectors in the area.

Great Central Mines opened the Jundee mine in early 1996, and following its takeover of Eagle Mining in 1997, expanded the operation to include the neighbouring Nimary mine. The combined operation was purchased by Normandy Mining in 2000, with ownership transferring to Newmont Mining Corporation in 2002.

Jundee was acquired by Northern Star Resources Limited in July 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.

Mining

Currently all ore is sourced from Jundee underground operations which yield ~1.0M 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.

Processing

The Jundee processing circuit is a conventional CIL plant with a hard rock processing capacity of approximately 1.35M 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.