Bowdens Silver Deposits

  • Mine Name:  Bowdens Silver Deposit
  • Commodities produced:  Silver (lead, zinc)
  • Operating company:  Silver Standard Australia Pty Ltd
  • Status: feasibility study
  • Background and Geological Setting:

The Bowdens silver-lead-zinc deposit is located 25 kilometres southeast of Mudgee and contains at a 40 g/t equivalent cut-off grade, a measured /indicated resource at April 2004 totalling 47.6 Mt @ 51.93 g/t Ag, 0.41% Zn and 0.3% Pb. There is an inferred resource of 13.4 Mt grading 40.9 g/t Ag, 0.32% Zn and 0.21% Pb.

The shallowly dipping mineralisation is hosted by Early Permian felsic volcanic rocks and, to a lesser extent, in the underlying units. The mineralisation occurs as finely disseminated or, less commonly, as small aggregates and veins of pale yellow sphalerite, galena, pyrite and silver bearing sulphides and sulphosalts with accessory arsenopyrite. The sulphides occur in epigenetic veins, as breccia-matrix fill, and as widespread disseminations within the altered host. The mineralisation is interpreted as forming at shallow crustal levels and at relatively low temperatures within a hydrothermal system and the deposit contains many features typical of a low-sulphidation type silver-gold-base metal system.

Broken Hill Mine

  • Mine Name:  Broken Hill Mine
  • Commodities produced:  Zinc, lead and silver
  • Operating company: Perilya Limited
  • Status: Underground mine in production
  • Background and Geological Setting:

The Broken Hill silver-lead-zinc deposit was discovered in 1883 at Broken Hill in far western New South Wales.  This world-class deposit contained an estimated 280 Mt of ore prior to mining.  The ore grades ranging from 2.5 to 15% Pb, 20 to 300 g/t Ag and 5 to 20% Zn.  The oxidised part of the Broken Hill ore zones contained spectacular lead and silver grades and a diverse range of secondary minerals.  Perilya acquired the mine from Pasminco Limited in May 2002.  At June 2004, resources at Perilya's South, North and Potosi mines were 21.132 Mt at 10.2% Zn, 5.7% Pb and 60 g/t Ag.  The proven and probable reserve was 11.662 Mt at 7.8% Zn, 4.1% Pb and 44 g/t Ag. 

The ore-body is hosted by Willyama Supergroup - a package of regionally metamorphosed clastic and volcaniclastic sediments, basic to acid volcanics and intrusions that range in age from about 1715 to 1590 Ma. The Broken Hill orebody contains six stacked, tabular lenses that strike northeasterly and dip steeply to the northwest. The mineralised system has an overall strike length of about eight kilometres. Though later folding and faulting has complicated the geometry, the ore lenses are conformable with the enclosing metasedimentary rocks.

Theories as to the origin of the mineralisation are varied, but there is a general consensus that mineralisation was concurrent with or soon after deposition of the sediments that contain the deposit.  Some workers interpret the mineralisation as diagenetic. The main sulphides are galena and sphalerite while the gangue mineralogy includes spessartine garnet, quartz, rhodonite, bustamite, hedenbergite, wollastonite, calcite, fluorite and apatite. Each ore lens has characteristic lead:zinc ratio and gangue mineralogy.

Cadia

  • Mines:  Cadia Hill Mine and Ridgeway Mine
  • Commodities produced: Gold and Copper
  • Operating company: Newcrest Mining Ltd
  • Status: Cadia Hill open-cut mine has been in production since 1998. Ridgeway Mine was officially opened in April 2002 and is in full production.
  • Background and Geological Setting:

The Cadia porphyry system is located 20 kilometres south of Orange within Late Ordovician volcanics and sediments of the Molong Volcanic arc. The sequence has been intruded by Late Ordovician intrusives including the Cadia Hill Monzonite. The area contains at least six significant mineralised zones. These are the porphyry-hosted, sheeted vein, low-grade copper-gold at Cadia Hill, distal skarn copper-gold-magnetite mineralisation at Big Cadia and Little Cadia, volcanic wall-rock hosted disseminated and sheeted vein mineralisation at Cadia East, intrusive-hosted sheeted vein mineralisation at Cadia Quarry, and quartz vein stockwork mineralisation at Cadia Ridgeway. Resources of well over 900 tonnes of gold and 4 million tonnes of copper are indicated for all the Cadia mineralising systems.

The Cadia Hill porphyry copper-gold mineralisation consists of chalcopyrite and native gold with lesser bornite within or disseminated near quartz veins. Cadia Hill reserves were 210 Mt at 0.72g/t Au and 0.18% Cu.  Mining commenced in 1998 with an expected mine life of 12 years.  At the end June 2004, over 1.4 million ounces (44 tonnes) of gold and nearly 140,000 tonnes of copper have been extracted.

The Ridgeway underground copper-gold mine is located approximately 3 km north-west of the Cadia Hill open-cut mine. The Ridgeway mineralisation is hosted by a quartz stockwork and sheeted vein system that carries magnetite, bornite, chalcopyrite, and free gold. Surrounding the high-grade core is a lower grade halo of similar mineralogy and an outer envelope of disseminated pyrite and chalcopyrite. Total reserves are 41Mt at 2.4 g/t  Au and 0.75% Cu for 3.2 million ounces of gold and 310,000 tonnes of copper.  Annual production is nominally at 5 Mt of ore per year with an expected mine life of 12 years.  Total metal production to the end of 2003-04 financial year was just over one million ounces of gold and nearly 120,000 tonnes of copper.

Cowal Gold Project

  • Mine Name:  Cowal gold project
  • Commodities produced:  Gold
  • Operating company:  Barrick Gold of Australia Limited
  • Status: Mine construction commenced in February 2004
  • Background and Geological Setting:

The Cowal Gold Project, located 125 kilometres southwest of Parkes, contains reserves (at December 2002) of 68.875 Mt at 1.27 g/t Au for 2.83 million ounces gold. The gold mineralisation is hosted by the Ordovician Lake Cowal Volcanic Complex. Later diorites and granodiorites of Middle to early Late Ordovician age have intruded the Complex. The gold mineralisation is structurally controlled, with gold occurring in narrow dilatant veins and within fault zones consisting of quartz-carbonate- sulphide and carbonate-sulphide � quartz, veins. The mineralised veins are predominantly adjacent to north-trending faults.  Production is expected to commence in 2005.

CSA Mine

  • Mine Name:  CSA mine
  • Commodities produced:  Copper (silver)
  • Operating company:  Cobar Management Pty Ltd (a fully owned subsidiary of Glencore Australia Pty Ltd.)
  • Status: producing underground mine.
  • Background and Geological Setting:

The CSA mine is located 9 kilometres north of Cobar in central western New South Wales. The CSA Mine reserves/ resources position as of July 2002 was published as a proven reserve of 0.71Mt @ 6.01% Cu and an inferred resource of 4.97 Mt @ 3.90% Cu.

The gold-copper-lead-zinc deposit is hosted by the Early Devonian CSA Siltstone, a thinly bedded turbiditic sequence of carbonaceous siltstones and mudstones with minor coarser units. The CSA mineralisation is confined to a number of steeply dipping bodies within a major shear zone on the eastern margin of the Early Devonian Cobar Basin. The mineralisation comprises of alteration and low-grade mineralisation enveloping higher -grade shoots of vein complexes or sub-massive to massive sulphides. The sulphides include chalcopyrite, pyrrhotite, pyrite, sphalerite, galena, bornite and cubanite. The five main ore systems are characterised by a complex array of overlapping alteration and mineralisation types.

Endeavour Mine

  • Mine Name:  Endeavour Mine (formerly known as the Elura Mine)
  • Commodities produced:  Zinc (lead, silver)
  • Operating company: Consolidated Broken Hill Ltd
  • Status: Underground mine in production
  • Background and Geological Setting:

The Endeavour mine is located 43 kilometres north northwest of Cobar in central western New South Wales. In June 2004, a total Mineral Resource was reported of 15.5 Mt at 8.7% Zn,  5.4% Pb,  67 g/t Ag and 0.2% Cu.  The total ore reserve was 11 Mt at 8% Zn, 4.8% Pb and 68 g/t Ag.

The Endeavour Mine zinc-lead-silver deposit is the largest mineral deposit yet found in the Cobar Basin. The deposit is hosted by moderately deformed turbiditic siltstones and mudstones, interpreted to be part of the CSA Siltstone, and consists of seven crudely elliptical vertical pipe-like bodies of massive sulphides. The sulphides consist of sphalerite, galena, and pyrrhotite with minor arsenopyrite, chalcopyrite, and tetrahedrite. Six styles of mineralisation are now recognised at Endeavour.

Ginko Mineral Sand Deposit

  • Mine Name:  Ginkgo Mineral Sand Deposit
  • Commodities produced:  Rutile, Zircon, and Ilmenite
  • Operating company:  BeMaX Resources NL
  • Status: feasibility study completed, mining lease granted
  • Background and Geological Setting:

The Ginkgo mineral sand deposit is located 30km west of Pooncarie and contains an indicated resource of 205Mt at 3.2% heavy minerals. The heavy mineral assemblage averages 12% rutile, 10% zircon and 67% ilmenite (includes altered ilmenite and leucoxene). The Gingko deposit is a coarse-grained beach placer that occurs in the Pliocene Loxton-Parilla Sands, beneath some 12m of overburden. The Ginkgo deposit strikes northwesterly, is about 14km in length, and is typically 20 to 40 metres thick. The unusual thickness is most likely due to barrier stacking, and the deposit is up to 800m wide. The recently discovered Snapper deposit, which occurs nearby, has the potential to significantly extend the projected life of the Ginkgo deposit. Snapper has an inferred resource of 104Mt at 4.8% heavy minerals. The mineral assemblage, which averages 15% rutile, 11% zircon and 66% ilmenite (includes altered ilmenite and leucoxene), indicates that Snapper has marginally higher amounts of rutile and zircon than the Ginkgo deposit.

Hillgrove Gold Mine

  • Mine Name:  Hillgrove Gold Mine
  • Commodities produced:  Antimony, gold
  • Operating company:  Straits Resources Limited
  • Status: Mine development, resource and exploration drilling.  Plan for re-opening  is underway.
  • Background and Geological Setting:

The Hillgrove gold-antimony mine, located 23 km east of Armidale. The gold/antimony/tungsten mineralisation is contained within metahydrothermal veins. Over 200 veins have been identified in a 9km x 7km area. The high grade, multi-stage mineralised veins are structurally controlled and developed after cooling and fracturing of the granite and diorite, with most mineralisation developed within the host metasedimentary rocks.

The area has been a significant producer with over 25 tonnes of gold, 34 000 tonnes of antimony, and 200 tonnes of tungsten (as scheelite) being recovered. Gold occurs as native gold disseminated in quartz veins and quartz breccia veins, or combined with arsenopyrite, or within stibnite as part of the crystal lattice. Lamprophyre dykes have a spatial and temporal relationship with the mineralisation but were not the source of the mineralising fluids.

Straits Resources are conducting an extensive underground and surface exploration program within the Hillgrove Mine and the surrounding tenements.  The first stage of the exploration program is designed to define the nature and the grade distribution of the two principal deposits planned for restart: the Eleanor and Brackins Spur deposits.  This will also test the regional area for open pit potential and for higher grade gold vein systems.  Current resources reported at inferred status are in the order of 340,000 ounces of gold.

Mineral Hill

  • Mine Name:  Mineral Hill
  • Commodities produced:  Copper/gold concentrate
  • Operating company:  KBL Mining Limited
  • Status: underground mine in production
  • Background and Geological Setting:

The Mineral Hill gold-copper mine is located 67 kilometres north-northwest of Condobolin in central New South Wales. Mineralisation was discovered at Mineral Hill in 1908 and small-scale mining was active throung to the 1960s. The current underground mining operation commenced in 1995.  In excess of 280,000 ounces of gold have been produced since 1995.  Total mineral resources at June 2003 were 831,500 tonnes at 7.47 g/t Au (uncut) and 4.8 g/t (cut) and 1.22% Cu. Development exploration is still revealing additional resources.

The Mineral Hill mineralisation is contained within the Late Silurian to Early Devonian Mineral Hill Volcanics that consists of felsic volcanic and clastic sedimentary rocks. A number of different mineralisation styles have been recognised. These include: silver-lead mineralisation with minor gold, copper and zinc which were mined between 1911 and 1925; gold-copper mineralisation with lead and bismuth and minor zinc and silver; and predominantly zinc-lead mineralisation with minor copper and gold-silver. The mineralisation is largely structurally controlled although some conformable mineralisation has been recognised.

Murrawombie Mine

  • Mine Name: Murrawombie mine (formerly the Girilambone Copper mine)
  • Commodities produced:  Copper (gold)
  • Operating company:  Tritton Resources Ltd 
  • Status: open-cut operations being developed.
  • Background and Geological Setting:

The geology at Girilambone, 20km to the north, is very similar to that found at Tritton, with the exception that the quartzite is less well developed in the northern areas.  Mineralisation within the Murrawombie deposit is controlled by several cross-cutting structures and is open to the south-east and at depth.  Copper mineralisation is hosted within quartz veins in the form of chalcopyrite in the primary zone.

The deposit contains a total resource (measured/indicated/inferred) of 1.2 Mt at 1.8% Cu and 0.03 g/t Au.  The company plans to extract 309,000tonnes of sulphide ore from the Murrawombie open pit and truck the ore to Tritton.  This will enable commissioning of plant at the Tritton mine to occur as soon as the processing plant is constructed.  It will also provide flexibility of supply during the initial underground development at Tritton.  It is expected that mining and plant commissioning will occur in late 2004.

Northparkes

  • Mine Name: Northparkes
  • Commodities produced:  Copper concentrate (copper, gold, and silver)
  • Operating company:  Rio Tinto Limited
  • Status: Underground block caving and open-cut mining
  • Background and Geological Setting:

The Northparkes copper-gold mine is located 26 kilometres north-northwest of Parkes in central New South Wales. Open pit reserves of 9.9 Mt at 0.55 g/t Au and 0.68% Cu, and underground reserves of 48.0 Mt at 0.5 g/t Au and 1.2% Cu were reported in December 2002. In addition, open pit resources were 14 Mt at 0.5 g/t Au and 0.6% Cu, and underground resources were 9.6 Mt at 0.2 g/t Au and 1.1% Cu.

Porphyry-type mineralisation (Endeavour 22, Endeavour 26 North, Endeavour 27, and Endeavour 48 deposits) is contained within units of the Late Ordovician Goonumbla Volcanic Group. The mineralisation is hosted by a series of sub-vertical pipe-like intrusions of quartz monzonite with the mineralisation occurring as disseminations and within fractures and veins within both the intrusion and the surrounding volcanic rocks. The strongest mineralisation is associated with quartz stockwork veining within a central, potassic alteration zone while pervasive sericitic alteration and widespread propylitic alteration have also been identified.

Peak Gold Mine

  • Mine Name:  Peak Gold Mine
  • Commodities produced:  Gold (copper, lead, zinc)
  • Operating company:  Wheaton River Minerals Ltd
  • Status: Mining of New Occidental, New Cobar and Perseverance deposits.
  • Background and Geological Setting:

The Peak Gold mine is located 8 kilometres southeast of Cobar in central western New South Wales. The mining operation consists of several underground and open pit ore bodies located on the eastern margin of the Cobar Basin.  The Peak operation produces approximately 130,000 ounces of gold and 18,000 tonnes of copper concentrate per year.  As of December 2002, proven and probable reserves were 2.35 million tonnes at 6.48 g/t of Au and 0.54% Cu.  Measured and indicated reserves were 1.04 milliom tonnes at 3.73 g/t Au and 0.96% Cu and inferred reserves were 3.2 million tonnes at 8.4 g/t Au and 1.2% Cu.

The gold-copper-lead-zinc mineralisation at the Peak is confined to a number of steeply dipping bodies within a major shear zone on the eastern margin of the Early Devonian Cobar Basin. The majority of the mineralisation is hosted by the Early Devonian Chesney Formation. With the mineralisation being localised about and within rhyolite or rhyolitic breccia bodies of uncertain affinity. The mineralisation is characterised by a complex array of overlapping alteration and mineralisation types with at least two stages of sulphide generation being recognised. The sulphides, which include pyrrhotite, chalcopyrite, sphalerite, galena, and pyrite, occur as splashes, fracture fillings, veins and disseminations.

Peak Hill Gold Mine

  • Mine Name: Peak Hill Gold Mine
  • Commodities produced: Gold
  • Operating Company:  Alkane Exploration Ltd
  • Status: open-cut mining operations ceased, heap leaching production for gold
  • Geological Setting:

The Peak Hill Gold Mine is located 50 kilometres north of Parkes in central New South Wales. Mining has ceased and a small anount of gold continues to be produced as part of the decommissioning process.

The deposit occurs in altered Ordovician andesitic volcanic and volcaniclastic rocks, and is currently interpreted as a porphyry related, high sulphidation epithermal deposit that has been variably oxidised to depths of up to 120m. A core of argillic to advanced argillic alteration, comprising silica, pyrophyllite, and sericite with variable barite, sulphide and alunite, occurs in a broad envelope of propylitic alteration. Below the oxidised zone, mineralisation in the sulphide zone is found within silica-sulphide-barite "lodes" or zones and within pyrophyllite-sulphide alteration. Interpretation of aeromagnetic data suggests a possible buried intrusive body below the main alteration zone and hence potential for porphyry copper-gold mineralisation at depth.

Alkane Exploration has recently discovered extensive mineralisation north of Peak Hill near Tomingley.  The Tomingley gold project hosts the Wyoming gold deposits, which also occurs in Ordovician rocks.  Alkane's geological modelling has identified a bulk resource of 6.38 million tonnes grading 2.43 g/t gold at 0.75 g/t gold cut off (498,000 ounces) at  Wyoming.  Resource modelling with the aim of improving open pitable grades is continuing with extensive RC and aircore drilling being carried out.

Prungle Mineral Sand Project

  • Mine Name: Prungle Mineral Sand Project
  • Commodities produced:  Rutile, Zircon, and Ilmenite
  • Operating company:  Murray Basin Titanium Pty Ltd
  • Geological Setting:

The Prungle mineral sand project, which is located about 50km northeast of Euston, consists of three nearby deposits: Cylinder, Karra and Finigans Tank. Karra and Finigans Tank will be mined in conjunction with Cylinder. The Prungle deposits are coarse-grained beach placers that occur within the Pliocene Loxton-Parilla Sands.

The Prungle project has an indicated resource of about 33.1Mt at 3.9% heavy minerals and an inferred resource of about 119.7Mt at 4.5% heavy minerals. Karra, which is the most important of these deposits, strikes northwesterly, is about 9km in length, 450m wide, some 12m thick and has an overburden thickness of about 42m. The heavy mineral assemblage for Cylinder and Karra averages 17% rutile, 13% zircon and 58% ilmenite (including altered ilmenite and leucoxene). Finnigans Tank has comparatively higher rutile, about 30%, and correspondingly lower amounts of zircon and ilmenite (including altered ilmenite and leucoxene).

Tritton

  • Mine Name: Tritton
  • Commodities produced:  Copper, (gold, and silver)
  • Operating company:  Tritton Resources Ltd
  • Status: open-cut and underground mine operations being developed.
  • Background and Geological Setting:

 
The Tritton copper deposit is located 85 kms east of Cobar and 18 kms north east of Hermidale. The mineralised zone is hosted by a moderately folded sequence of pelitic schists, mafic schists, shales, greywackes and quartzites. The Tritton mineralisation, which commences at around 180 m below surface, is contained within two approximately tabular bodies of chalcopyrite with massive pyrite.

The mineralisation has been emplaced along a shear and in a brittle fracture within the quartzites. The hanging wall contact of both zones is sharp whereas stringer chalcopyrite mineralisation occurs below the footwall of the lower massive sulphide zone. Mineralisation extends along a strike length of 450m with an average width of 15m.  The orebody remains open at depth and along strike.  The deposit contains a total resource (measured/indicated/inferred) of 14.00 Mt at 2.7% Cu, 0.3 g/t Au, 12 g/t Ag.  Commissioning of the mine commenced in December 2004 with initial production from the lower grade Murrawombie Open Pit before the longer term higher grade underground mine is operational in early 2005.  When fully operational it is expected that the mine will have a life of at least 11 years, with annual ore production of between 660,000 and 900,000 tonnes per annum.  

Twelve Mile Mineral Sand Project

  • Mine Name:  Twelve Mile Mineral Sand Project
  • Commodities produced:  Rutile, Zircon, and Ilmenite
  • Operating company:  Murray Basin Titanium Pty Ltd
  • Geological Setting:

The Twelve Mile mineral sand project, which is located about 40km east of Pooncarie, consists of three nearby deposits: Birthday Gift, Triangle and Western Strands. Western Strands and Triangle will be mined in conjunction with Birthday Gift. The Twelve Mile deposits are coarse-grained beach placers that occur within the Pliocene Loxton-Parilla Sands.

The Twelve Mile project has an indicated resource of about 33.9Mt at 3.4% heavy minerals and an inferred resource of about 82.1Mt at 2.7% heavy minerals. The heavy mineral assemblage averages 12% rutile, 9% zircon and 57% ilmenite (including altered ilmenite and leucoxene). Birthday Gift is the most important of the three deposits. This deposit strikes northwesterly, is up to 15km long, 10-20m thick, about one km in width, some 10-15m deep, and consists of stacked deposits up to 50m wide and up to 10m thick. In contrast, the (lower grade) Western Strands and Triangle deposits tend to consist of scattered patches of high grade material within an envelope of lower-grade disseminated heavy minerals.