Exploration for magnesiteand brucite in Quebec

SUMMARYTo meet customer’s needs, Canada imports more than $50 million worth of magnesite and magnesium oxidea year, and the United States more than $100 million US worth of magnesium oxide. The situation thuspresents an excellent opportunity for promoting the exploration and development of magnesite and brucitedeposits in Quebec.

The Kilmar region and neighbouring areas in the metasedimentary rocks of the Grenville Supergroup providethe best potential for magnesite in Quebec. As far as brucite is concerned, the most promising sectors are inthe Precambrian marbles of the Grenville Supergroup near Wakefield, along the Gatineau River, near Bryson,on the shores of the Ottawa River and around Lac Saint-Jean.

USESMagnesite (MgCO3) is a carbonate mineral. Most of the magnesite mined around the world is calcined toproduce magnesium oxide, which is mainly used as a refractory raw material. Magnesite is also used toproduce magnesium metal by one plant in the Province of Quebec. Brucite (Mg(OH)2) is a magnesium hydroxidemineral that could be used for the same purposes as magnesite.

PRICEGiven their many uses and characteristics, the prices of magnesium compounds are extremely variable butgenerally increase with the purity of the compound. Crude (raw) magnesite sells for less than $60 US/t,whereas magnesium oxide or hydroxide prices range from $100 to $900 US/t.

OUTLOOK AND BUSINESS OPPORTUNITIESThe North American magnesium oxide and magnesite markets are highly dependent on imports, which representnearly three quarters of the demand. This presents an attractive situation for a prospective producer in Quebec.In fact, American production of caustic and refractory magnesia is declining, and consequently imports are onthe rise. In 2002, imports supplied 80 % of the US demand, for a total of 560,000 t and a value of more than$100 million US.

In Canada, magnesite imports amount to about 185,000 t/yr for a value of about $14 million. The mineral isessentially used by a magnesium producer in Becancour, Quebec. In addition, imports of magnesium oxideand other magnesium compounds total 80,000 to 100,000 t/yr, for a value of $40 million. The main sources ofimported magnesia are the United-States and China, with more than 60% of the material entering into Quebec.Currently, the only Canadian producer of magnesite supplies only calcined products. Its annual exports ofmagnesia are about 60,000 t, for a value of $20 to $30 million.

The most immediate opportunity for a potential new magnesite mine would be the magnesiumplant in Becancour.

Brucite deposits in QuebecIn Quebec, 24 brucite deposits have been catalogued in Precambrian marbles of the Grenville Supergroup.Most of them are in the Wakefield area along the Gatineau River. Other deposits occur in the Bryson area, onthe shores of the Ottawa River, and around Lac Saint-Jean (Hébert and Conrad, 1990).

Exploration criteriaIn order to be viable, it is imperative that deposits be of high purity, about 45-46 % MgO for magnesite and 65-66 % for brucite, in order to produce a calcined product with at least 95-96 % MgO. Magnesite ore should nothave to be concentrated since purification costs would make it less competitive than crude magnesite availablefrom other countries. This presents the challenge of defining a high quality deposit. Since brucite is richer inmagnesium than magnesite, it could possibly be concentrated and still remain economic.

In addition, a deposit would need to have a volume of at least 2 Mt to be economic and be located neartransportation corridors, as close to the users as possible.

BIBLIOGRAPHYBAIN, G. M., Types of magnesite deposits and their origin, Econ. Geol., Volume 19, 1924, pages 412-433.BODENLOS, A. J., Magnesite deposits in the Serra das Éguas, Brumado, Bahia, Brazil, US Geol. Surv.

Bulletin 975 C, 1954, pages 87-170.GENEST, S., Histoire géologique du Bassin d’Otish, Protérozoique Inférieur (Québec), thèse de doctorat,

Université de Montréal, 1989, 336 pages.HARBEN, P. W., KUZVART, M., Industrial Minerals, A global Geology. Industrials Information Ltd., Metal

Bulletin, PLC London, 1996.HÉBERT, Y., CONRAD, P.,Les ressources en minéraux de magnésium et leur utilisation au Québec, Ministère

de l’Énergie et des Ressources du Québec, MB 90-31, 1990.NEWMAN, T. E., HOFFMAN, G. K., Brucite deposit in Marble Canyon, Culberson County, Texas in Proceedings,

31st Forum on the Geology of Industrial Minerals, G. S. Austin, G. K., Hoffman, J. M. Barker, J. Zidek,and N. Gilson, editions New Mexico Bur. Mines & Mineral Resources, Bulletin 154, 1996, pages 37 42.

For more information, see:www.mrnfp.gouv.qc.ca/mines/mineraux/mineraux-magnesitewww.sidex.ca

Major producing countries of magnesite in 2002

Brazil2,3%

Canada1,6%

India3,3%

Australia4,2%

Greece4,3%

Slovakia4,3%

Austria6,0%

Russia8,6%

North Korea8,6%

Turkey17,2%China

31,9%

Others countries7,6%

GEOLOGY – ORE DEPOSITSMagnesite

Hydrothermal magnesite deposits associated with carbonate rocksMagnesite deposits associated with carbonate rocks are the most commercially significant since they arethe largest and are relatively pure (Harben and Kuzvart, 1996). Deposits of this type occur in Austria, Slovakia,Russia, Saudi Arabia, Brazil and Canada (British Columbia). They result from hydrothermal or metasomaticreplacement of dolomite, limestone, or sandy and graphitic argillaceous shale formations affected by orogenicand magmatic events (Blain, 1924 and Bodenlos, 1954).

Hydrothermal magnesite deposits associated with ultramafic rocksGenerally speaking, magnesite deposits associated with ultramafic rocks are not very large and are thus lessinteresting than those associated with carbonate rocks. They occur in Quebec as well as in Europe, Australia,Asia and the United States. They form by the passage of CO2-rich hydrothermal solutions that transformmagnesium-rich serpentine into magnesium carbonate (Harben and Kuzvart, 1996).

Magnesite deposits associated with sedimentary rocksCryptocrystalline massive magnesite deposits can develop in lagoons, salt lakes and fresh water bodies.These deposits occur in Russia, Germany, Poland and former Yugoslavia. Deposits in China and Korea arealso typically associated with sedimentary rocks (Harben and Kuzvart, 1996).

BruciteBrucite deposits are formed during metamorphic processes at the contact between granitic intrusions andmagnesium limestone or dolomitic limestone. Brucite originates by de-dolomitization due to thermalmetamorphism and from magnesium enrichment related to intrusive activity (Newman and Hoffman, 1996).

Magnesite deposits in QuebecMagnesite occurs in the Kilmar, Otish Mountains and Thetford-Mines areas of the Grenville, Superior andAppalachian tectonic provinces respectively.

KilmarThe Kilmar area is located betweenOttawa and Montreal, 15 km north ofthe Ottawa River, where dolomiticmagnesite deposits occur in themetasedimentary rocks of the GrenvilleSupergroup. Magnesite-rich zones arepresent in the marbles between thealuminous gneisses to the east, andthe quartzites to the west.

Otish MountainsA white, cryptocrystalline magnesitewith very low iron content outcrops 7km NE of Lac Indicateur, which islocated some 90 km northeast of LacMistassini. The Gaschet Formation (Peribonka Group) consists of an assemblage of magnesite,dolomite and pyrolusite-hematite sediments (Genest, 1989). Unfortunately, the remoteness of thisshowing presents a significant drawback.

Thetford-MinesAt Thetford-Mines, a zone of talc and carbonate alteration has been observed in association with theThetford fault zone, extending northeast for 3 km along the footwall of the zone that hosts the asbestosdeposits. The magnesite occurs in the tectonite-type serpentinized peridotite at the base of theThetford-Mines Ophiolitic Complex. The magnesite grades reported in this area are not very high.

Grey magnesite bands in dolomitic marble at the old Gamble mine(Kilmar area).

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GEOLOGY – ORE DEPOSITSMagnesite

Hydrothermal magnesite deposits associated with carbonate rocksMagnesite deposits associated with carbonate rocks are the most commercially significant since they arethe largest and are relatively pure (Harben and Kuzvart, 1996). Deposits of this type occur in Austria, Slovakia,Russia, Saudi Arabia, Brazil and Canada (British Columbia). They result from hydrothermal or metasomaticreplacement of dolomite, limestone, or sandy and graphitic argillaceous shale formations affected by orogenicand magmatic events (Blain, 1924 and Bodenlos, 1954).

Hydrothermal magnesite deposits associated with ultramafic rocksGenerally speaking, magnesite deposits associated with ultramafic rocks are not very large and are thus lessinteresting than those associated with carbonate rocks. They occur in Quebec as well as in Europe, Australia,Asia and the United States. They form by the passage of CO2-rich hydrothermal solutions that transformmagnesium-rich serpentine into magnesium carbonate (Harben and Kuzvart, 1996).

Magnesite deposits associated with sedimentary rocksCryptocrystalline massive magnesite deposits can develop in lagoons, salt lakes and fresh water bodies.These deposits occur in Russia, Germany, Poland and former Yugoslavia. Deposits in China and Korea arealso typically associated with sedimentary rocks (Harben and Kuzvart, 1996).

BruciteBrucite deposits are formed during metamorphic processes at the contact between granitic intrusions andmagnesium limestone or dolomitic limestone. Brucite originates by de-dolomitization due to thermalmetamorphism and from magnesium enrichment related to intrusive activity (Newman and Hoffman, 1996).

Magnesite deposits in QuebecMagnesite occurs in the Kilmar, Otish Mountains and Thetford-Mines areas of the Grenville, Superior andAppalachian tectonic provinces respectively.

KilmarThe Kilmar area is located betweenOttawa and Montreal, 15 km north ofthe Ottawa River, where dolomiticmagnesite deposits occur in themetasedimentary rocks of the GrenvilleSupergroup. Magnesite-rich zones arepresent in the marbles between thealuminous gneisses to the east, andthe quartzites to the west.

Otish MountainsA white, cryptocrystalline magnesitewith very low iron content outcrops 7km NE of Lac Indicateur, which islocated some 90 km northeast of LacMistassini. The Gaschet Formation (Peribonka Group) consists of an assemblage of magnesite,dolomite and pyrolusite-hematite sediments (Genest, 1989). Unfortunately, the remoteness of thisshowing presents a significant drawback.

Thetford-MinesAt Thetford-Mines, a zone of talc and carbonate alteration has been observed in association with theThetford fault zone, extending northeast for 3 km along the footwall of the zone that hosts the asbestosdeposits. The magnesite occurs in the tectonite-type serpentinized peridotite at the base of theThetford-Mines Ophiolitic Complex. The magnesite grades reported in this area are not very high.

Grey magnesite bands in dolomitic marble at the old Gamble mine(Kilmar area).

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Exploration for magnesiteand brucite in Quebec

SUMMARYTo meet customer’s needs, Canada imports more than $50 million worth of magnesite and magnesium oxidea year, and the United States more than $100 million US worth of magnesium oxide. The situation thuspresents an excellent opportunity for promoting the exploration and development of magnesite and brucitedeposits in Quebec.

The Kilmar region and neighbouring areas in the metasedimentary rocks of the Grenville Supergroup providethe best potential for magnesite in Quebec. As far as brucite is concerned, the most promising sectors are inthe Precambrian marbles of the Grenville Supergroup near Wakefield, along the Gatineau River, near Bryson,on the shores of the Ottawa River and around Lac Saint-Jean.

USESMagnesite (MgCO3) is a carbonate mineral. Most of the magnesite mined around the world is calcined toproduce magnesium oxide, which is mainly used as a refractory raw material. Magnesite is also used toproduce magnesium metal by one plant in the Province of Quebec. Brucite (Mg(OH)2) is a magnesium hydroxidemineral that could be used for the same purposes as magnesite.

PRICEGiven their many uses and characteristics, the prices of magnesium compounds are extremely variable butgenerally increase with the purity of the compound. Crude (raw) magnesite sells for less than $60 US/t,whereas magnesium oxide or hydroxide prices range from $100 to $900 US/t.

OUTLOOK AND BUSINESS OPPORTUNITIESThe North American magnesium oxide and magnesite markets are highly dependent on imports, which representnearly three quarters of the demand. This presents an attractive situation for a prospective producer in Quebec.In fact, American production of caustic and refractory magnesia is declining, and consequently imports are onthe rise. In 2002, imports supplied 80 % of the US demand, for a total of 560,000 t and a value of more than$100 million US.

In Canada, magnesite imports amount to about 185,000 t/yr for a value of about $14 million. The mineral isessentially used by a magnesium producer in Becancour, Québec. In addition, imports of magnesium oxideand other magnesium compounds total 80,000 to 100,000 t/yr, for a value of $40 million. The main sources ofimported magnesia are the United-States and China, with more than 60% of the material entering into Quebec.Currently, the only Canadian producer of magnesite supplies only calcined products. Its annual exports ofmagnesia are about 60,000 t, for a value of $20 to $30 million.

The most immediate opportunity for a potential new magnesite mine would be the magnesiumplant in Becancour.

Brucite deposits in QuebecIn Quebec, 24 brucite deposits have been catalogued in Precambrian marbles of the Grenville Supergroup.Most of them are in the Wakefield area along the Gatineau River. Other deposits occur in the Bryson area, onthe shores of the Ottawa River, and around Lac Saint-Jean (Hébert and Conrad, 1990).

Exploration criteriaIn order to be viable, it is imperative that deposits be of high purity, about 45-46 % MgO for magnesite and 65-66 % for brucite, in order to produce a calcined product with at least 95-96 % MgO. Magnesite ore should nothave to be concentrated since purification costs would make it less competitive than crude magnesite availablefrom other countries. This presents the challenge of defining a high quality deposit. Since brucite is richer inmagnesium than magnesite, it could possibly be concentrated and still remain economic.

In addition, a deposit would need to have a volume of at least 2 Mt to be economic and be located neartransportation corridors, as close to the users as possible.

BIBLIOGRAPHYBAIN, G. M., Types of magnesite deposits and their origin, Econ. Geol., Volume 19, 1924, pages 412-433.BODENLOS, A. J., Magnesite deposits in the Serra das Éguas, Brumado, Bahia, Brazil, US Geol. Surv.

Bulletin 975 C, 1954, pages 87-170.GENEST, S., Histoire géologique du Bassin d’Otish, Protérozoique Inférieur (Québec), thèse de doctorat,

Université de Montréal, 1989, 336 pages.HARBEN, P. W., KUZVART, M., Industrial Minerals, A global Geology. Industrials Information Ltd., Metal

Bulletin, PLC London, 1996.HÉBERT, Y., CONRAD, P.,Les ressources en minéraux de magnésium et leur utilisation au Québec, Ministère

de l’Énergie et des Ressources du Québec, MB 90-31, 1990.NEWMAN, T. E., HOFFMAN, G. K., Brucite deposit in Marble Canyon, Culberson County, Texas in Proceedings,

31st Forum on the Geology of Industrial Minerals, G. S. Austin, G. K., Hoffman, J. M. Barker, J. Zidek,and N. Gilson, editions New Mexico Bur. Mines & Mineral Resources, Bulletin 154, 1996, pages 37 42.

For more information, see:www.mrnfp.gouv.qc.ca/mines/mineraux/mineraux-magnesitewww.sidex.ca

Major producing countries of magnesite in 2002

Brazil2,3%

Canada1,6%

India3,3%

Australia4,2%

Greece4,3%

Slovakia4,3%

Austria6,0%

Russia8,6%

North Korea8,6%

Turkey17,2%China

31,9%

Others countries7,6%