Australian magnesite: Recovery and expansion

By IM Staff
Published: Friday, 18 March 2016

Australia hosts some 95m tonnes magnesite reserves and has been a major supplier of the global market for much of the last century. Cameron Perks, IM Correspondent, and Richard Flook, Consultant*, examine the history of Australian magnesite and discuss some of the new projects underway that look set to restore the sector’s former glory.

Australia hosts some 330m tonnes of economic demonstrated magnesite resources, including 95m tonnes of reserves. The industry is starting to recover from recent slumps in demand and a number of explorers are looking to develop new resources, particularly for Asia-Pacific export markets.



According to the Queensland state government, the Kunwarara deposit in central Queensland is the world’s largest known source of ultrafine-grain cryptocrystalline to microcrystalline nodular magnesite and is the only magnesium carbonate mine belonging to Belgian speciality mineral company, Sibelco.

Myrtle Springs magnesite mine. 
(Calix Mining)

Magnesite was discovered at Kunwarara in 1985 by Queensland Metals Corp. (QMC), which quickly recognised the deposit’s refractory grade potential. Kunwarara produced its first magnesite in 1991 under QMC, later renamed Queensland Magnesia Ltd (QMAG). In 2012, QMAG was purchased by Sibelco, in an acquisition underlining the company’s long term optimistic view of the market. 

QMAG commenced mining at the Yaamba magnesite deposit in September 2010. Together, the Kunwarara and Yaamba mines produced magnesite worth just over Australian dollar (A$) $45m ($33.2m**) in the 2014-15 financial year. Approximately 3m tpa run of mine (ROM) ore is produced from Kunwarara and 1m tpa from Yaamba. In the 2013-14 financial year, QMAG’s Queensland operations produced 586,495 tonnes magnesite, rising to 658,562 tonnes in 2014-15.

ROM ore is crushed, scrubbed and screened at the mine site, which has a processing capacity of about 600,000 tonnes. The processed ore is then sent to the Parkhurst processing plant for further beneficiation. Parkurst is one of the world’s largest magnesite processing plants, with 340,000 tpa calcination capacity for final products, electrofusion capacity of 32,000 tpa and deadburning capacity of 110,000 tpa. 

Fused and deadburned magnesia (FM and DBM) products are supplied to the refractories industry and caustic calcined magnesia (CCM) is supplied for agricultural, metallurgical, paper and environmental applications. 

South Australia

Calix Ltd operates the Myrtle Springs mine in the Leigh Creek area of South Australia. The deposit has a total exploration target of around 3m tonnes and in 2013, Calix produced 3,632 tonnes magnesite. Magnesite ore mined at Myrtle Springs is sent to the company’s Bacchus Marsh plant, where it is crushed, milled and calcined. Calix also heats magnesite using method called "flash calcination", where the mineral is heated indirectly and in the presence of steam, affecting the surface area and pore size and hence the reactivity of the magnesium oxide formed. Bacchus Marsh has capacity of 4 tph of fully calcined high value products and 9 tph of partially calcined lower value products.

Calix is now supplying its newly commissioned magnesium hydroxide liquid (MHL) production plant in Queensland in order to better serve customers in that state. The plant has a capacity of 6,000 tonnes per operating shift and the capability to produce a batch of 60% solids MHL in less than 90 minutes. Magnesium oxide (MgO) feed powder is sourced from the Bacchus Marsh plant.

New South Wales

New South Wales magnesite is sourced solely from Causmag International’s Thuddungra project, which has a measured resource of 3.8m tonnes grading at 55.1% magnesium carbonate (MgCO3). The ore is cryptocrystalline and nodular, high quality (>99.8% MgCO3) and suitable for refractories and pharmaceuticals. Thuddungra produced up to 30,000 tonnes magnesite in 2015, according the GSNSW. CCM is produced in rotary and shaft kilns and, according to Causmag, its products go into fertilisers, animal feed, pharmaceuticals, water treatment and soil remediation applications.

World magnesite reserves totalling 2.4bn tonnes, with Australia containing 
95m tonnes, or 4% (excludes the US). 

Source: USGS 2016


Australian magnesite and magnesia export trade

Trade data is notoriously misleading, due to local data restrictions and limitations as well as re-exports. However, a combination of export and import data, along with some commercial knowledge, can usually identify significant trends. 

Australia is a small importer of magnesite, at about 5,000 tpa, but is a significant exporter of both magnesite and magnesia (FM, DBM and CCM). Prior to 2009, the year in the aftermath of the global economic crash, exports had reached 150-200,000 tpa and recovered to this level shortly after 2009. Australian exports then declined rapidly to about 100,000 tonnes in 2013, before rebounding slightly in 2014. Exports of hydrometallurgical caustic magnesia are considered to be understated in the data prior to 2012 and the decline in exports may be larger than indicated.

This period coincided with the change of ownership of the largest producer and exporter, Sibelco’s QMAG, the reaching of "peak refractories demand" and increased competition in export markets for hydrometallurgical grade CCM. Significantly, the recovery of exports in 2014 was predominantly in markets closer to Australia (New Zealand, India, Indonesia and New Caledonia) and mainly for CCM. 

Trade data indicates a pickup in exports to the US in 2015, which is back to historical levels of about 35,000 tpa, as well as indicating retention of exports to New Zealand of about 27,000 tpa. The growth of Australian CCM exports into the large and mostly agricultural New Zealand market against Chinese production is a significant trend.

Australia also increased exports of DBM to India in 2014 and again in 2015, with competition mainly from Turkey (Kümaş Kütahya Manyezit Sanayi AŞ). For the two-year period 2014-2015, Australia supplied 52% of total DBM imports to India, with Turkey and China supplying 38% and 9%, respectively.

Cross-section of palaeochannel fill in the Thuddungra district (diagrammatic only)

Source: GSNSW, David Forster


Exploration in Australia is being spurred on by a perceived increase in international demand for raw magnesite, DBM, CCM, FM, magnesium metals, and more recently, speculation about the potential of magnesium-ion batteries. Market analysis carried out by Rockstone Research in 2015 determined that demand for FM is growing at twice the rate of other magnesia products.

Australian magnesite and magnesia exports (tonnes) 2010-2014

Source: Trade data, various sources

South Australia

Australia’s largest magnesite ore body is the Leigh Creek deposit, having JORC measured, indicated and inferred resources of 453m tonnes, grading at 41.4% MgO. Leigh Creek is also the world’s largest cryptocrystalline magnesite deposit. The owner of the project, Archer Exploration Ltd, plans to produce either CCM or DBM suitable for a range of monolithic applications. In February 2016, Archer appointed Paul Rix, ex-general manager marketing for Sibelco’s QMAG, as a director.

Archer, through its subsidiary Leigh Creek Magnesite Pty Ltd, holds four exploration licences in South Australia, while Agricola Mining Pty Ltd holds one.

New Zealand magnesite and magnesia imports (tonnes) 2010-2015 

Source: Richard Flook, Mosman Resources 

Northern Territory

In the Northern Territory, exploration is focused on the Huandot, Area 44 and Winchester deposits, all located within about 80km south of Darwin.

At the Winchester deposit, exploration is progressing under Ausmag Pty Ltd, a wholly-owned subsidiary of Korab Resources Ltd. Winchester is held over a granted mining lease and is being developed to produce high grade, direct shipping ore grade magnesite to supply producers of MgO, refractories and other uses. The company says that the "market for magnesium carbonate has been growing at a strong historical trend rate (…) over several decades, with the trend pointing to yet higher consumption over coming years."

In December 2015, Korab and AusMag entered into a memorandum of understanding with "interests associated with the Chinese steel industry, with a view to funding the development, operation and commencement of producing magnesium carbonate from the Winchester mine, offtake agreements with Chinese steel industry and listing AusMag on Shanghai, Hong Kong, or another suitable stock exchange". In January 2016, Korab revealed that discussions were with Shandong Iron and Steel Group Co. Ltd, which has requested samples of magnesite rock from Winchester for testing. 

The Huandot and Area 44 deposits are owned by Thessally Resources, which holds two exploration licences and two exploration licence applications in the Northern Territory.

The Huandot deposit hosts a JORC indicated and inferred mineral resource of around 9m tonnes, grading at 44% MgO, with much of the deposit having a purity greater than 44% MgO, according to Thessally. Thessally previously undertook a scoping study on the basis of direct shipping magnesia for export. The study contemplated a 20-year mine life, producing 300,000 tpa and will extend this research into a currently prefeasibility study for the production of CCM for export into Southeast and east Asia. 

Area 44, less advanced than Huandot, has an exploration target of 6-18m tonnes, grading at 41-43% MgO.

Indian magnesite and magnesia imports (tonnes) 2010-2014 

Source: Richard Flook, Mosman Resources

New South Wales

New South Wales hosts large, ultrapure, cryptocrystalline and nodular magnesite deposits, as well as widespread regolith hosted replacement deposits. According to the GSNSW, the state has previously produced around 1m tonnes magnesite from the BHP mine near Thuddungra, as well as about 895,000 tonnes hard magnesite (99.19% MgO calcined) from the Fifield magnesite mine. In addition, New South Wales hosts the Cargelligo (Whitton Road) deposits, with 93.4-97.3% MgCO3 and ferric oxide from 0.5–1.8%; the Noakes deposit, with a measured resource of 12.6m tonnes grading at 43% MgCO3; and numerous other opportunities across the state.

The serpentinite-hosted cryptocrystalline Attunga deposit in the northeast of the state was the source of about 100,000 tonnes of characteristically high-purity magnesite from 1916 to 1960.

Western Australia

In Western Australia, BMAG holds the granted mining lease M74/110 over the Bandalup Magnesite deposit, 20km east of Ravensthorpe and immediately adjacent to Canadian miner First Quantum Minerals Ltd’s Ravensthorpe nickel operations. 

According to BMAG, the site was a historical production centre for beneficiated magnesite and has metallurgical evaluations showing that the product has the ability to produce CCM suitable for agricultural and nickel hydrometallurgical applications. Trial work is underway to determine if 200,000 tonnes of fines stockpiled on site are suitable for kiln feed. Total estimated reserves of magnesite at Bandalup are around 3.4m tonnes.


Fine-grained, massive magnesite, formed by the replacement of limestone and dolomite, occurs at Arthur River and in the Lyons River area 50km south west of Burnie.

The Arthur River deposit in Tasmania, hosts 25m tonnes magnesite, based on a 40% MgO cut-off and 42.4% MgO average grade to a maximum depth of 40 metres. The resource, which is not currently held under any exploration licence, is part of a much larger global resource of 195m tonnes in Tasmania’s Arthur-Lyons River area, about 53km south of Burnie. 

Selected products and end uses derived from magnesite, excluding magnesium metal



Crude/raw magnesite

Feedstock for DBM, FM and CCM. 

Fertiliser, acid soil agent, fillers, glass.


Feeds into DBM and EFM.

Paints, paper, water treatment, plastics, rubber, oil, pharmaceutical products, fertiliser, animal feed, building materials, fire retardants,  

acid neutralisation, hydrometallurgy, slag conditioner, magnesium chemicals

DBM (sintered magnesia or clinker)

Refractory bricks to line steel making furnaces. 


Premium grade refractory bricks, electrical substrates, high temperature insulators, and ceramics special refractory applications in the nuclear and space industries.

Magnesium metal’s false starts

As well as being the feedstock for FM, DBM and CCM, magnesite is also the principal source of magnesium metal. Australia does not currently produce magnesium metal, even though it has abundant magnesium sources. Several companies have tried and failed to start magnesium metal processing plants across the country. 

Australian Magnesium Corp. had intended to build a magnesium smelter using the electrolytic route in Queensland, but closed down in 2003 before production began.

The South Australian Magnesium project (or SAMAG), owned by Pima (later known as Magnesium International Ltd), had plans in the early 2000s to build a magnesium plant at Port Pirie in South Australia. The project intended to utilise the large Leigh Creek deposit to provide raw material in a Dow process. However, it failed in 2003-2004, when SAMAG failed to raise the necessary capital to develop the $670m, 520,000 tpa plant, at a time when the magnesium metal market was experiencing a downturn as a result of Chinese over supply and escalating construction and power costs.

LaTrobe Magnesium plans to build a 40,000 tpa smelter (using the Pidgeon process technology) from brown coal fly ash, produced as a by-product of nearby power generation in Latrobe Valley, Victoria. LaTrobe is currently in the feasibility study phase, which it expects to complete in April 2016. Typical lignite coal fly ash has an MgO content of 3-10% and calcium oxide (CaO) content of 15-40%.  

The location of the Leigh Creek Magnesite project, currently held under an exploration
licence by Archer and its proximity to Port Pirie and Adelaide in the south. 
Archer Exploration
The meaning of magnesite

Magnesite refers to magnesium carbonate (MgCO3, theoretically 47.8% MgO and 52.2% CO2) but is also sometimes used to refer to magnesia products made from natural magnesite or synthetic magnesia. It occurs in two physical forms: cryptocrystalline (or amorphous) magnesite and macrocrystalline magnesite. It occurs in five different ways: as a replacement mineral in carbonate rocks; an alteration product in ultramafic rocks; a vein-filling material; a sedimentary rock; or, as nodules formed in a lake environment. However, according to the Geological Survey of New South Wales (GSNSW), Australian magnesite deposits differ from European types often quoted in the relevant literature on the mineral, as they have arguably been developed via low temperature groundwater, rather than high temperature hot springs.

According to studies by Pohl and Brownlow, in 1989 and 2007, respectively, stratabound sedimentary sparry magnesite deposits generally provide the best economic potential for the use of magnesite as a refractory in steel, cement, glass and copper industries because of their larger volume and relative ease of mining. However, according to the study by Pohl, some ultramafic hosted, cryptocrystalline-nodular magnesite deposits have been exploited due to the higher purity of the magnesite.

The pathway of carbon in ultramafic-hosted magnesite vein and massive deposits has been subject of continuing debate in scientific literature. This may have direct implementation in industrial, in situ, or passive mineral carbonation approaches, due to it being a potential natural analogue for carbon sequestration and storage.


About the Authors

Cameron Perksis a freelance writer and industrial minerals consultant. Cameron previously worked with the Geological Survey of New South Wales and has also worked with CSIRO, developing methods to eliminate low frequency noise in SQUID magnetometers.

Dr Richard Flook has worked for both suppliers and consumers of minerals with global companies including, Steetley plc, Anglo American, Commercial Minerals (now Sibelco), Normandy Mining Ltd, Omya AG and Shinagawa Refractories.Since commencing consulting in 2014, Richard’s clients have come from five continents.

**Conversion made March 2016