Magnesite

Content maintained by Roy Towner

• Magnesite
• Resources
• Accessible EDR
• JORC Reserves
• Exploration
• Production
• World Ranking
• Industry Developments

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 for use in cement, glass, steel and in 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.

Economic Demonstrated Resources (EDR) of magnesite remained unchanged at 344 million tonne (Mt) in 2008. South Australia (SA) has Australia's largest holding of EDR with 235 Mt of magnesite, which is unchanged from 2006.

Queensland (Qld) has Australia's second largest inventory of magnesite EDR. The bulk of this occurs at Kunwarara 70 kilometres (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, the company has identified several high-grade magnesite zones which are classified as EDR. The Kunwarara deposit contains substantial accumulations of very high-density 'bone-type' magnesite characterised by nodular and cryptocrystalline structure and low iron-content.

The third largest inventory of EDR is in Tasmania (Tas) where the Arthur River deposit has an indicated resource of 26 Mt. Magnesite in the deposit typically grades at 42.8% magnesium oxide (MgO) and is part of a much larger global resource of 195 Mt in the Arthur-Lyons River area, about 53 km south of Burnie in Tas.

Minor EDR occurs in the Winchester deposit near Batchelor 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 2006. All of these resources occur in Qld and Tas.

Inferred resources remained steady at 931 Mt with Qld accounting for 50% followed by SA with 31% and Tas with 16%. The remaining resources are in NSW and the NT.

All magnesite EDR is accessible for mining.

About 11% of AEDR comprise JORC Code reserves. The remainder represents resources assessed by Geoscience Australia from the measured and indicated categories of industry reported mineral resources as defined under the JORC Code and other classification systems used by companies not listed on the Australian Stock Exchange. At Australia's 2007 rate of production, magnesite resources in the JORC Code reserves categories are adequate for 84 years.

Data relating to exploration expenditure for magnesite are not published by the Australian Bureau of Statistics (ABS).

The bulk of Australia's magnesite production was by Queensland Magnesia Pty Ltd which supplies high-grade electrofused and deadburned magnesia to the global refractory market, as well as calcined magnesia for a wide range of applications. In 2007-08, the company produced 124 681 tonne of raw magnesite. About 1530 tonne of magnesite was produced from the Myrtle Springs region in SA during 2007-08.

The United States Geological Survey (USGS) data indicate that China (45%), Turkey (13%), North Korea and Russia (8% each) were the largest producers of magnesite in 2008.

According to Geoscience Australia and the USGS data, Australia has about 5% of the world's EDR of magnesite. Russia, North Korea and China jointly account for almost 70% of the world's EDR. The Kunwarara deposit in Qld is the world's largest known resource of cryptocrystalline nodular magnesite, a high quality ore.

Queensland Magnesia Pty Ltd announced plans to expand its total magnesia capacity from 220 000 tonne per annum (tpa) to 320 000 tpa, add a third multiple hearth furnace and diversity its markets into hydrometallurgical and agricultural applications. Construction of the third multiple hearth furnace is scheduled to be completed in December 2009.