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:

1. crude magnesite, primarily for use in chemicals and agriculture;
2. dead-burned magnesia, a durable refractory for use in cement, glass, steel and in metallurgical industries; and
3. caustic calcined magnesia, for use in making oxychloride and oxysulphate cements for flooring and wallboards, mouldings and acoustic tiles, and various environmental and chemical applications.

EDR of magnesite remained unchanged at 344 Mt in 2007. SA has the largest holding of EDR with 579 Mt of magnesite. About 235 Mt of this resource is classified as EDR, which is unchanged from 2006.

QLD has Australia's second largest inventory of magnesite EDR. The bulk of this occurs at Kunwarara 70 km north west of Rockhampton, where QLD 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 Tas where the Arthur River deposit has an indicated resource of 26 Mt. Magnesite in the deposit typically grades at 42.8% 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.

Minor EDR occurs in the Winchester deposit near Batchelor, NT, at Thuddungra 80 km north west of Young, NSW, and at Bandalup 20 km east of Ravensthorpe, 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% and the remainder in NSW and NT.

All magnesite EDR is accessible for mining.

About 11% of AEDR comprise JORC Code reserves. The remaining represents resources assessed by Geoscience Australia from the measured and indicated categories of industry reported mineral resources as defined under the 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 ABS on either a State or National basis.

According to ABARE, magnesite production in 2007 totalled 447,000 t. The bulk of production was by Queensland Magnesia Pty Ltd which supplies high-grade electrofused and deadburned magnesia to the global refractory market and is expanding calcined magnesia production for a wide range of applications. About 2500 t of magnesite was produced from the Myrtle Springs region in SA.

USGS data indicate that China (41%), Russia (20%), North Korea and China (8% each) were the largest producers of magnesite in 2007.

According to Geoscience Australia and USGS data, Australia has about 5% of the world's EDR of magnesite. Russia, North Korea and China, together, 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 t/year to 320,000 t/year, add a third multiple hearth furnace (MHF), and to diversity its markets into hydrometallurgical and agricultural applications. Construction on the third MHF is scheduled to commence in July 2008 with commissioning to begin in September 2009.