Magnesite

This information has not been updated since 2013 and is provided for general reference purposes. For the latest data, please see Australia's Identified Mineral Resources 2016.

Magnesite (magnesium carbonate MgCO3) is marketed in three main forms:

  • Crude magnesite, primarily for use in chemicals and agriculture
  • Dead-burned magnesia, a durable refractory used in the cement, glass, steel and metallurgical industries
  • Caustic calcined magnesia, for use in making oxychloride and oxysulphate cements for flooring and wallboards, mouldings and acoustic tiles as well as various environmental and chemical applications.

Resources

Economic Demonstrated Resources (EDR) of magnesite remained unchanged in 2012 at 330 million tonnes (Mt). South Australia (SA) continued to have Australia's largest holding of EDR with 235 Mt, which is unchanged from 2006. The bulk of these resources occur as interbeds of sedimentary magnesite within the Skillogalee Dolomite at the Witchelina and Mount Hutton deposits, up to 30 kilometres (km) northwest of Leigh Creek in SA. The average magnesite grade is 40% magnesium oxide (MgO).

Queensland (Qld) has Australia's second largest inventory with 63 Mt of magnesite EDR. The bulk of this resource occurs at Kunwarara, 70 km northwest of Rockhampton, where Queensland Magnesia Pty Ltd has global resources of 1200 Mt of magnesite-bearing material. Within this global resource, which has an Inferred Resource of 500 Mt of magnesite, several high-grade magnesite zones have been classified as EDR. The Kunwarara deposit occurs as sheet-like lenses of magnesite with an average thickness of 7.6 metres extending over about 63 square kilometres. It contains four high-grade zones of very high-density bone-type, low iron ultrafine-grained cryptocrystalline to microcrystalline nodular magnesite.

The third largest inventory of EDR is in Tasmania (Tas) where the Arthur River deposit has a measured resource of 13.2 Mt with an average magnesite grade of 43.4% magnesium oxide (MgO). The resource is part of a much larger global resource of 195 Mt in Tasmania's Arthur-Lyons River area, about 53 km south of Burnie. The remainder of Australia's EDR occurs in the Winchester deposit 70 km south of Darwin in the Northern Territory (NT), at Thuddungra 80 km northwest of Young in New South Wales (NSW) and at Bandalup 20 km east of Ravensthorpe in Western Australia (WA).

Subeconomic Demonstrated Resources of 57 Mt of magnesite remained unchanged from 2011. All of these resources occur at Triple Four in central Qld and at Main Creek in northwest Tas.

Inferred Resources of magnesite remained unchanged in 2012 at 836 Mt with Qld accounting for 56%, followed by SA with 35% and Tas with 5%. The remaining resources are in NSW, the NT and WA.

Accessible EDR

All magnesite EDR is accessible for mining.

JORC Reserves

Joint Ore Reserves Committee (JORC) Code reserves comprise total magnesite in Proved and Probable Ore Reserves as defined in the JORC Code. In 2012, JORC Code reserves of 37.5 Mt (unchanged from 2011) accounted for approximately 11% of Accessible Economic Demonstrated Resources (AEDR). At Australia's 2012-13 rate of production, magnesite resources in the JORC Code reserves categories are adequate for almost 64 years.

Exploration

Data associated with exploration expenditure for magnesite are not published by the Australian Bureau of Statistics.

Production

The bulk of Australia's magnesite production was by Queensland Magnesia Pty Ltd which supplied high-grade electrofused and dead-burned magnesia to the global refractory market, as well as calcined magnesia for a wide range of applications. In 2012-13, the company produced a total of 587 688 tonnes of magnesite (644 325 tonnes in 2011-12). About 3595 tonnes of magnesite was produced from the Myrtle Springs region in SA in the six months to June 30th 2012.

World Ranking

According to Geoscience Australia and United States Geological Survey (USGS) data, Australia has about 4% of the world's EDR of magnesite, which total 8300 Mt. Russia, China and North Korea jointly account for almost 67% of the world's EDR. The Kunwarara deposit in Qld is the world's largest known resource of ultrafine-grained cryptocrystalline to microcrystalline nodular magnesite.

According to USGS data, estimated world production of magnesite totalled 21.16 Mt (20.65 Mt in 2011). The world's largest producers of magnesite in 2012 were China (70%), Russia (6%), Turkey (5%), and Austria (4%).

Industry Developments

Korab Resources Limited had entered into an agreement to sell the Winchester magnesite deposit located in the NT for up to $33.2 million in cash and royalties to Augur Investments Oü, a diversified Estonian investment company with interests in mining, infrastructure and commercial property development. The company negotiated a sale price of $2 a tonne of JORC code compliant magnesite resource. The current resource base consists of an Indicated Resource of 12.2 Mt at 43.1% MgO and an Inferred Resource of 4.4 Mt at 43.6% MgO. $16.6 million ($1 per tonne of resource) was payable on completion of the sale and an additional $1 a tonne of resource ($16.6 million) was payable as a royalty on each tonne of magnesite mined from the deposit. The amount of royalties was capped at $16.6 million. The agreement was subject to Korab Resources obtaining all regulatory and other approvals necessary for the sale of the assets, including the consent of the relevant Minister under the Northern Territory Mineral Titles Act. It was dependant also on Augur Investments completing a due diligence in relation to the transaction, but in May 2013, Augur advised that it would not proceed with the purchase of the Winchester deposit.

Beacon Hill Resources Plc, through its subsidiary Tasmania Magnesite NL, holds mineral tenure over two large, high-grade magnesite deposits at Arthur River and Lyons River in northwest Tas. The company announced the results of a preliminary scoping study into the Arthur River project in the June quarter 2012. The study demonstrated a pre-tax nett present value of $42 million based on a mine life of 17 years and a 292 000 dry tonnes per annum (tpa) operation producing on average 100 000 tpa of caustic-calcined magnesia with an average grade of 95% MgO. The study was based on an Inferred Resource of 25 Mt of magnesite grading 42.4% MgO, 4.8% SiO2, 1.4% Fe2O3 and 2.6% CaO to a maximum depth of 100 metres below the surface at a cut-off grade of 40% MgO. Initial capital cost is estimated at $155 million with an average life of mine operating cost, including both mining and processing costs, of approximately $250 a tonne free-on-board.

The company plans to move towards a full feasibility study, which would include the submission of a development proposal and environmental management plan to secure mining approval, the completion of the approved drilling program to upgrade resources and the securing of a joint venture and/or off-take partner to fund the future development of the project.

Archer Exploration Limited is planning to develop a 150 000 tpa caustic-calcined magnesia operation based on magnesite resources that occur on two Exploration Licences, one covering the Mount Hutton, MountPlayfair, Termination Hill and Pug Hill deposits, and the other covering the Witchelina deposit. These licences were granted to Archer Exploration Limited through its wholly-owned subsidiary, Leigh Creek Magnesite Pty Ltd, in late 2010-early 2011. These deposits, formerly owned by SAMAG, to supply magnesite to its proposed magnesium metal plant at Port Pirie, SA, contain a combined JORC Code compliant resource of 413 Mt with an average grade of 41.3% MgO. SAMAG failed to raise the necessary capital to develop the magnesium metal plant and the plan was abandoned. Archer Exploration is seeking joint venture partners with technical and marketing expertise in magnesia industry to assist in the development of deposits.

In April 2012, the global industrial minerals group Sibelco acquired QMAG Limited from Resource Capital Funds, a private equity company with a mining focus. The acquisition included the magnesite resource at Kunwarara, the mining, beneficiation and the production of dead-burned, electrofused and calcined magnesia products at its mine and production facilities in Rockhampton. Sibelco, with over 200 production sites in 41 countries, operates a network of 45 mines, plants, and distribution warehouses in Australia and New Zealand. The company supplies products to the glass, mining, agriculture, construction, and manufacturing industries. Foyson Resources Limited, formerly known as Magnesium International Limited (MIL), has sold its Myrtle Springs magnesite tenements comprising two mining leases and two mining purpose leases located 20 km west-northwest of Leigh Creek in SA to Calix Limited and its wholly-owned subsidiary MS Minerals Pty Limited for $1 million (excluding GST). The magnesite tenements were part of MIL's magnesium smelter project (SAMAG project) proposed for Port Pirie in the early 2000s. The combined Measured, Indicated and Inferred Resources of magnesite of Foyson Resources' tenements formed part of the totalled 579 Mt grading on average 42% MgO associated with the SAMAG project. Calix Limited is an Australian mineral processing and carbon capture technology company which operates a large-scale calciner at Bacchus Marsh, 40 km northwest of Melbourne in Victoria.

McKay, A.D., Miezitis, Y., Porritt, K., Britt, A.F., Champion, D.C., Cadman, S., Towner, R., Summerfield, D., Whitaker, A., Huston, D., Jaireth, S., Sexton, M., Schofield, A., Hoatson, D., Senior, A.B. & Carson, L., 2014. Australia's Identified Mineral Resources 2013. Geoscience Australia, Canberra, Australia. http://dx.doi.org/10.11636/1327-1466.2013