Tungsten

Hatches Creek: The historic Hatches Creek mineral field is located 375 km northeast of Alice Springs within Paleoproterozoic metasedimentary and igneous rocks of the Warramunga Province. The granite-related tungsten mineralisation occurs as wolframite-bearing, quartz-vein systems and is also associated with bismuth, copper, molybdenum, cobalt, lead, silver and minor tin and uranium mineralisation⁷. Between 1913 and 1977, Hatches Creek produced some 3065 t of 65% WO₃ concentrate from shallow lodes grading at 1-3% WO₃, along with by-product concentrates of copper (70 t) and bismuth (5.7 t)⁸.

In 2014, Arunta Resources Ltd published an Inferred Resource of 225 kt at 0.58% WO₃ for the historical mine dumps and stockpiles⁹. In May 2019, GWR Group Ltd released the results of a 13-hole RC drilling campaign, reporting high-grade mineralisation that included individual 1-m intercepts of 4.68% WO₃, 3.06% Cu and 3578 ppm Mo¹⁰. In June 2019, Tungsten Mining NL farmed into the project with an initial interest of 20%. Tungsten Mining has not yet progressed the project but must within five years of the farm-in date if it wishes to increase its share of the project to 51%¹¹.

Molyhil and Bonya: Tungsten and molybdenum mineralisation was first encountered at Molyhil in 1973. The deposit is situated 220 km northeast of Alice Springs (320 km by road). It consists of two adjacent magnetite skarn bodies with scheelite, molybdenite and magnetite mineralisation. The skarns are hosted by the Marshall Granite in the Aileron Province.

Fama Mines Pty Ltd worked the deposit from 1973 to 1977, when Petrocarb Exploration NL acquired the project. Petrocarb continued open-cut operations, then placed the mine on care and maintenance in 1982 owing to low tungsten prices.

During 2018, Thor Mining Plc completed an upgraded Definitive Feasibility Study at Molyhil and finalised the purchase of a 40% interest in the nearby Bonya Project¹². The Bonya Project is a joint venture with Arafura Resources Ltd, who own the remaining 60%, located approximately 30 km east of Molyhil.

During 2019, Thor continued marketing activities aimed at securing finance and offtake agreements for tungsten and molybdenum concentrates. In October 2019, the company reported a combined resource at Molyhil of 4.7 million tonnes (Mt) at 0.28% WO₃, 0.14% Mo, 0.05% Cu and 18.0% Fe above a cut-off grade of 0.12% WO₃ equivalent¹³. The revised estimate represents a 1.5% increase of contained tungsten trioxide, a 9.3% increase in contained molybdenum and a new copper resource.

In January 2020, the joint venture partners announced maiden resource estimates for the White Violet and Samarkand tungsten deposits at the Bonya Project¹⁴. For White Violet, this was an Inferred Resource of 495 kt, grading 0.22% WO₃ and 0.06% Cu, containing 1.09 kt of tungsten trioxide and 0.3 kt of copper. For Samarkand, the Inferred Resource is 245 kt, grading 0.19% WO₃ and 0.13% Cu, containing 465 t of tungsten trioxide and 320 t copper. For the Bonya copper deposit, the company previously announced an Inferred Resource of 230 kt, grading 2.0% Cu, containing 4.6 kt copper¹⁵.

Mount Carbine: Discovered in the late 19th century, 120 km northwest of Cairns, Mount Carbine comprises wolframite and scheelite in sheeted quartz veins within metasedimentary rocks of the Hodgkinson Formation. Mineralisation is thought to be related to the nearby Permian Mount Carbine Granite. The historic mine, which operated between 1973 and 1987, is owned by Specialty Metals International Ltd (formerly Carbine Tungsten Ltd). The tailings dams are estimated to contain approximately 2 Mt at 0.1% WO₃¹⁶.

Carbine announced a favourable feasibility study in August 2012 for the economic viability of re-establishing the Mount Carbine tungsten mine¹⁷. The study considered an open-cut, hard-rock resource along with processing previously stockpiled low-grade material in order to achieve a 15-year project life.

As a result of this study, resource upgrades were reported in June and August 2012. Using a 0.05% WO₃ cut-off grade, the revised estimates were an Indicated Mineral Resource of 18.1 Mt at 0.14% WO₃ and an Inferred Resource of 29.3 Mt at 0.12 % WO₃ for 60.5 kt of tungsten trioxide (48 kt of contained tungsten), beneath and adjacent to the previous open-cut mine¹⁸. The company considered the Indicated Resource to also be a Probable Reserve, based on mining 3 Mt per annum (Mtpa) and receiving a price of US$290/MTU¹⁹. Hard-rock mining would only commence after processing of the low-grade stockpile had begun²⁰.

In September 2012, Carbine Tungsten released an Indicated Resource of 12 Mt at 0.07% WO₃ for the low-grade stockpile²¹. The company reported a production target of 15 000 MTU of tungsten trioxide in concentrate per month from the low-grade stockpile, suggesting an 8-year mine life.

In 2019, Specialty Metals International reported the first delivery of equipment to the Mount Carbine site, as well the engagement of sub-contractors for the installation of the newly arrived equipment²². The company commenced tailings retreatment in the fourth quarter of 2019²³, with planning for stockpile processing and open-cut mining continuing in 2020. The company has reported the presence of scheelite mineralisation at the nearby Iron Duke and Petersens Lode exploration permits, and a potential copper-zinc drilling target at Iron Duke.

Watershed: The deposit is located 115 km northwest of Cairns and was originally discovered by Utah Development Company Ltd in the early 1980s. It consists predominantly of quartz-scheelite vein swarms within metasedimentary rocks of the Hodgkinson Province.

Vital Metals Ltd completed a Definitive Feasibility Study in 2014 and identified an open-cut mining method using excavators and trucks, with the potential to produce 2 Mtpa over an initial mine life of 10 years²⁴.

In July 2018, Vital Metals reported 70.4 kt of contained tungsten at a cut-off grade of 0.05%²⁵. Mineral Resources are 49.3 Mt at a combined grade of 0.14% WO₃ comprising Measured Resources of 9.47 Mt at 0.16% WO₃, Indicated Resources of 28.36 Mt at 0.14% WO₃ and Inferred Resources of 11.49 Mt at 0.15% WO₃. Ore Reserves, originally published in 2014, remain at 21.3 Mt grading 0.15% WO₃, comprising 6.4 Mt at 0.16% WO₃ in the Proved category and 15.0 Mt at 0.14% WO₃ as Probable²⁶.

In August 2018, Vital Metals completed the sale of the project to Tungsten Mining²⁷. No significant work has occurred since.

Dolphin: The deposit was discovered in 1911 and was mined intermittently until the 1990s, when low tungsten prices led to mine closure. Mining was originally open pit, until the 1970s, when operations transitioned to underground at both Bold Head and Dolphin. Bold Head, discovered in the 1960s, is a satellite deposit.

Located on King Island in Bass Strait, the deposits comprise tungsten and minor molybdenum mineralisation within scheelite skarns replacing dolomitic metasedimentary units of the Grassy Group. Mineralisation is related to the spatially associated Early Carboniferous granites.

In 2019, King Island Scheelite Ltd released a feasibility study and revised Ore Reserve and Mineral Resource estimates²⁸. Combined total Inferred and Indicated resources for the Dolphin Project (including Bold Head) are 11.36 Mt grading 0.90% WO₃.

Dolphin is a proposed open-cut mine with an Indicated Resource of 9.6 Mt at 0.90% WO₃ containing 86.4 kt tungsten trioxide at a cut-off grade of 0.20% WO₃. The Mineral Resource includes a Probable Reserve of 3.0 Mt at 0.73% WO₃.

The Bold Head deposit is a proposed underground resource with reported Indicated Resources of 1.61 Mt at 0.92% WO₃, containing 14.8 kt of tungsten trioxide at a cut-off grade of 0.5% WO₃, and an Inferred Resource of 0.15 Mt at 0.85% WO₃, containing 1.3 kt of tungsten trioxide at a cut-off grade of 0.5% WO₃.

The company reported an offtake agreement for tungsten concentrate with Austrian-based Wolfram Bergbau und Hutton AG, pending the achievement of operational and financial milestones prior to 31 March 2021²⁹. The agreement is for approximately 20% of the expected annual production at Dolphin, with full production expected to be in the order of 2000 t WO₃ per annum contained in 3100 t of concentrate.

Kara: Tasmania Mines Ltd produced 47 t of by-product tungsten concentrate in 2018 (almost 0.02 kt of contained tungsten) from its Kara No 1 magnetite mine (Table 2), 35 km south of Burnie in northwest Tasmania. The mine, which has been operating since 1977, produces magnetite and scheelite from skarn mineralisation that has replaced carbonates within Cambrian and Ordovician sediments close to the Devonian Housetop Granite.

In February 2017, Tasmania Mines released updated Ore Reserve figures for the mine including, at Kara No 1, total Ore Reserves of 9.97 Mt at 49.7% iron oxide (FeO) and 366 ppm WO₃. The Reserves include 624 kt Probable at 51.1% FeO and 799 ppm WO₃, and 9.3 Mt Proved at 49.6% FeO and 337 ppm WO₃³⁰.

Tasmania Mines holds additional resources in the vicinity of current mining operations³¹. The Eastern Ridge magnetic skarn, located to the northeast of Kara No 1, has a total Mineral Resource of 6.5 Mt at 48.3% FeO and 1045 ppm WO₃ which includes Indicated Resources of 5.24 Mt at 1200 ppm WO₃ and Inferred Resources of 1.26 Mt at 400 ppm WO₃. Kara North 266, located immediately to the north of Kara No 1, has a total Mineral Resource of 2.85 Mt at 47.3% FeO and 1891 ppm WO₃, which includes Indicated Resources of 2.59 Mt at 2000 ppm WO₃ and Inferred Resources of 0.260 Mt at 800 ppm WO₃. The Kara North Magnetic Anomaly has an Inferred Resource of 11.96 Mt at 42.7% FeO and 160 ppm WO₃³².

Mount Mulgine: Located 350 km north-northeast of Perth, the mineralisation represents an Archean porphyry tungsten-molybdenum system (Mulgine Hill) and associated skarn (Mulgine Trench), related to the Neoarchean Mount Mulgine Granite.

In April 2019, Tungsten Mining commenced a prefeasibility study for mining and processing tungsten and molybdenum at the Mount Mulgine Project.³³ The company commenced resource definition drilling in July 2019 and, in December 2019, reported an updated Inferred Resource estimate for the Mulgine Trench deposit of 207 Mt at 0.11% WO₃, 272 ppm Mo, 0.13 ppm gold (Au) and 5 ppm silver (Ag) at a 0.05% WO₃ cut-off grade.³⁴ This was a maiden resource for gold and silver and a significant increase to the Inferred tungsten-molybdenum resource, making Mulgine Trench the largest Inferred tungsten resource in Australia and the second largest total resource in Australia (behind O'Callaghans, see below).

Tungsten Mining continued infill drilling at Mulgine Trench and in May 2020 reported an Indicated Resource³⁵. The updated estimates are an Indicated Resource of 175 Mt at 0.11% WO₃, 290 ppm Mo, 0.14 ppm Au and 6 ppm Ag; and an Inferred Resource of 72 Mt at 0.11% WO₃, 250 ppm Mo, 0.10 ppm Au and 5 ppm Ag.

Mineral Resources for the Mulgine Hill deposit remained unchanged from March 2019 with total Indicated and Inferred Resources of 7.3 Mt, containing 16.1 kt tungsten trioxide and 942 t of molybdenum, reported above a 0.10% WO₃ cut-off grade. The Indicated Resource is 5.6 Mt, at 0.23% WO₃ and 133 ppm Mo. The Inferred Resource is 1.7 Mt at 0.19% WO₃ and 113 ppm Mo³⁶.

O'Callaghans: The polymetallic deposit is located approximately 400 km east-southeast of Port Hedland, and 10 km south of the processing plant at the operating Telfer copper-gold mine. Within the Telfer region of the Paterson Province, Newcrest Mining Ltd owns the Telfer mine, a group of gold deposits within a 30 km zone from Telfer and the O'Callaghans deposit. At O'Callaghans, skarn-hosted mineralization containing tungsten, copper, zinc and lead is found as a sub-horizontal layer at the contact between the limestone of the Proterozoic Puntapunta Formation and the Neoproterozoic O'Callaghans Granite. Although molybdenum and silver are present, they are not presently considered economically significant.

Newcrest states the O'Callaghans resource contains 0.26 Mt tungsten trioxide, 0.22 Mt copper, 0.38 Mt zinc, and 0.19 Mt lead. These comprise an Inferred Resource of 9 Mt at 0.25% WO₃, 0.24% Cu, 0.19% Zn and 0.11% Pb and an Indicated Resource of 69 Mt at 0.34% WO₃ 0.29% Cu, 0.53% Zn and 0.26% Pb. Included in the Mineral Resource is a Probable Ore Reserve of 44 Mt at 0.36% WO₃, 0.29% Cu, 0.65% Zn and 0.32% Pb, for a contained 0.16 Mt of tungsten trioxide, 0.13 Mt of copper, 0.29 Mt of zinc and 0.14 Mt of lead.³⁷ These figures are unchanged since 2016³⁸.

O'Callaghans is Australia's largest reported tungsten resource, with almost half of Australia's Economic Demonstrated Resources contained within the deposit.