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Jundee, Nimary

Western Australia, WA, Australia

Main commodities: Au
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The Jundee and the immediately adjacent Nimary Archaean gold deposits are located 500 km to the north of Kalgoorlie and 50 km NE of Wiluna. They are situated towards the northern extremity of the Yandal Greenstone Belt, which occupies the eastern margin of the northern half of the Kalgoorlie Terrane of the Yilgarn Craton in Western Australia.

The Yandal belt has few historic gold workings, sparse outcrop and a truncated lateritic profile. After a reconnaissance RAB drilling program that commenced in 1992, the deposit was discovered. Mining at Jundee commenced in mid 1995. The deposit was exploited from at least 5 open pits and an underground mine from 1997 within a 4 x 2.5 km area, and treated by a 3 mtpa capacity plant. Open pit mining ceased at Jundee in 1997. The Nimary deposit was initially mined separately from Jundee, but the two operations were amalgamated in 1997.

Regionally the west dipping host sequence of the greenstone belt comprises lower banded iron formations (BIFs) and mafic to ultramafic units, the Fisher Basalt, separated by a sedimentary sequence from the overlying tholeiitic and high-Mg basalt of the Lyons Basalt, that has been intruded by a suite of differentiated dolerite sills. This package hosts the mineralisation at Jundee-Nimary. Younger felsic and intermediate porphyries and dolerite dykes intrude the host sequence. The mine sequence is bounded to the west by a package of felsic to intermediate volcanics with minor chert, basalt and shale. To the east in the mine area, mineralisation diminishes as the mafic package becomes more high-magnesium to ultra-mafic in composition.

On a regional scale, Jundee-Nimary is part of an 80 km line of magnetic anomalies defining an inferred south-east trending shear zone. Jundee is at the contact between the mafic to ultramafics and the overlying acid to intermediate volcanics to the west.

On a district scale and in the mine, basalt and dolerite are important hosts, as are spatially associated feldspar rich porphyry dykes, due to their brittle behaviour during low grade metamorphism, and their iron content. The ore is localised in moderate to steeply dipping brittle-ductile structures with strike and down dip continuity and comprise veined and silicified shears, breccias and fracture-fill veins with strong carbonate, silica, sulphide, white-mica and leucoxene alteration.

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 typically have a tabular in geometry, and are narrow and highly discontinuous, occurring in multiple orientations. Proximal alteration is characterised by a quartz-sericite-ankerite-sulphide (pyrite ± arsenopyrite ± chalcopyrite) assemblage (Northern Star Resources website).

At the end of 1998 the total resource at Jundee-Nimary was - 41 Mt @ 5.1 g/t Au, for 210 t (6.75 Moz) of contained gold;
By June 2000 the resource was re-stated at - 17.1 Mt @ 7.4 g/t Au for 126 t Au (4.09 Moz);.
During 2007 the mine produced 9.27 t of recovered Au; ;
The remaining reserve at the end of 2007 was - 6.8 Mt @ 7 g/t Au for 47.5 t of contained Au (Newmont, 2008).

Remaining Measured + Indicated + Inferred Mineral Resources at 30 June, 2018 (Northern Star Resources Reserve and Resource statement, 2018) were:
  32 Mt @ 3.5 g/t Au

The most recent source geological information used to prepare this summary was dated: 2001.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.


Jundee

  References & Additional Information
   Selected References:
Anonymous  1998 - Jundee (GCM): in    Register of Australian Mining 1997/98    pp 113-114
Baggott M S, Vielreicher N M, Groves D I, McNaughton N J and Gebre-Mariam M,  2005 - Zircons, Dikes, and Gold Mineralization at Jundee-Nimary: Post ca. 2.66 Ga Archean Lode Gold in the Yandal Belt, Western Australia : in    Econ. Geol.   v100 pp 1389-1405
Bypass A P, Maclean D R  1998 - Nimary Gold Deposits: in Berkman D A, Mackenzie D H (Eds),  Geology of Australian and Papua New Guinean Mineral Deposits The AusIMM, Melbourne    pp 89-96
Hall D, Maclean D, Gebre-Mariam M  2003 - The discovery of the Westside gold deposit, Jundee - Nimary Goldfield, Western Australia: in   NewGenGold 2003, Conference Proceedings, Perth WA,  Louthean Media, Perth    pp 18-33
Phillips G N, Vearncombe J R, Eshuys E  1998 - Yandal Greenstone Belt, Western Australia: 12 million ounces of gold in the 1990 s: in    Mineralium Deposita   v33 pp 310-316
Phillips G N, Vearncombe J R, Murray R  1998 - Jundee Gold Deposits: in Berkman D A, Mackenzie D H (Eds),  Geology of Australian and Papua New Guinean Mineral Deposits The AusIMM, Melbourne    pp 97-104
Ryan D  1997 - Bronzewing and Jundee Gold Mines: Five Years after Discovery: in   World Gold 97 Conference, Singapore, Sept. 1997, Papers AusIMM, Melbourne    pp 227-231
Wright J H, Herbison I  1995 - The Yandal Belt - Preliminary Exploration of the Jundee Deposit: in   New Generation Gold Mines, Case Histories of Discovery, Conf. Proc., Perth, Nov, 1995 AMF, Adelaide    pp 5.1-5.12
Yeats, C.J., Kohler, E.A., McNaughton, N.J. and Tkatchyk, L.J.,  2001 - Geological setting and SHRIMP U-Pb geochronological evidence for ca. 2680-2660 Ma lode-gold mineralization at Jundee-Nimary in the Yilgarn Craton, Western Australia: in    Mineralium Deposita   v36 pp 125-136


Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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