Cambior Inc.: Increase in Mining Reserves and Feasibility Update for Cerro San Pedro Project, Mexico.

MONTREAL--(BUSINESS WIRE)--Sept. 13, 1999--

(ME:CBJ.) (TSE:CBJ.) (AMEX:CBJ) (ME;TSE;AMEX:CBJ)

All amounts in US dollars

Cambior Inc. and Metallica Resources Inc. announce an update of the mining reserves and an update to the feasibility study of the Cerro San Pedro gold and silver project, located in San Luis Potosi, Mexico. Proven and probable mining reserves currently total 64 million tonnes at 0.62 g Au/t and 24.5 g Ag/t, representing 1.3 million ounces of gold and 50.1 million ounces of silver, for a total of 2.2 million ounces of gold equivalent in situ. The reserves have been calculated using long-term price assumptions of $300 per ounce for gold and $5.50 per ounce for silver.

The mining reserves are contained within a designed pit with an overall slope of 48 degrees and an estimated waste to ore ratio of 1.6. Reserves were calculated using results from 94 diamond drill holes (16,180 metres), 161 reverse circulation drill holes (42,000 metres), and 2,150 underground channel samples (4,560 metres).

Despite the reduction in gold and silver price assumptions, this new reserve calculation at $300/oz of gold contains a total of 2,185,000 ounces of gold equivalent, an improvement of 65 percent over resources reported in 1998. This improvement is primarily a result of the drilling program executed since early 1998, the updated geological interpretation derived from this additional information, the reassaying of the silver sampling information and the addition of mixed ore based on metallurgical testing.

             September 1999      December 1998      December 1997
            Mining Reserves  Mineral Resources  Mineral Resources
               Designed Pit        Whittle Pit        Whittle Pit

               @$300/oz Au,       @$325/oz Au,       @$350/oz Au,
                $5.50/oz Ag           $5/oz Ag           $6/oz Ag
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Tonnes of Ore
 (millions)            63.5               42.8               55.8
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Grade
Gold (g/t)             0.62               0.60               0.57
Silver (g/t)           24.5               23.7               21.8
Gold Equivalent (g/t)   1.1                1.0                0.9
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Ounces
Gold (000)            1,265                820              1,017
Silver (000)         50,125             32,584             39,112
                     --------------------------------------------
Gold Equivalent (000) 2,185              1,321              1,688
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Strip Ratio            1.57               0.67               0.78
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Total Tonnes
 (millions)           163.1               71.4               99.2
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Recovery
Gold (percent)           71                 71                 71
Silver (percent)         43                 47                 47
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Recoverable Ounces
 (Au Eq) (000)        1,285                820              1,010
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On the basis of this reserve calculation, the sensitivity to long term gold price shows an increase of 5 percent in contained equivalent ounces when using a gold price assumption of $325 per ounce ($5.75/oz silver) and a decrease of 14 percent when using a gold price assumption of $275 per ounce ($5.25/oz silver).

The updated feasibility study of this open pit heap leach operation is being finalized on the basis of a processing rate of 8 million tonnes per year (22,000 tonnes per day). Average recoveries are expected at 71 percent for gold and 43 percent for silver, yielding an average annual production of 110,000 ounces of gold and 2.6 million ounces of silver, or approximately 160,000 gold equivalent ounces per year for a total recovery of 1,285,000 ounces of gold equivalent. The average cash mining cost including royalties is estimated at $190 per ounce of gold equivalent ($3.75 per tonne of ore).

The going forward capital, including working capital, is estimated at $70 million including the mining fleet. At a gold price of $300 per ounce, the project economic analysis shows an after-tax return of 15 percent on an all equity basis. Further sensitivity analysis will be completed to evaluate whether contract mining could improve project returns. Continuing efforts will focus on the completion of the permitting process as well as the purchase of all required surface and water rights. The Federal permitting process has been completed and state permitting is expected to be resolved by year end. The start of construction is dependent on the completion of the permitting process and improving gold markets.

Further to the joint venture agreement between Cambior and Metallica Resources of January 1998, Cambior is the project manager and is earning the right to acquire a 50 percent interest in the project by investing $20 million in project development expenditures. In addition, Cambior will provide project loan facilities of up to $60 million and gold and/or silver hedging facilities up to a maximum of 150,000 ounces of gold. By year end, Cambior expects to have incurred expenses of approximately $19 million for this project.

Cambior Inc. is an international diversified gold producer with operations, development projects and exploration activities throughout the Americas. Cambior is the first gold mining company to receive ISO 14001 certification of its environmental management system. Cambior's shares trade on the Toronto, Montreal and American (AMEX) stock exchanges under the symbol "CBJ".

Metallica is a Canadian precious metals exploration and development company focused on Latin America. Metalllica is well funded and has 24.5 million common shares outstanding.

This press release contains certain "forward-looking statements", as defined in the United States Private Securities Litigation Reform Act of 1995, that involve a number of risks and uncertainties. There can be no assurance that such statements will prove to be accurate and actual results and future events could differ materially from those anticipated in such statements.

Such risks and uncertainties are disclosed under the heading "Risk Factors" in Cambior's Annual Information Form (AIF) filed with the Ontario Securities Commission, the Quebec Securities Commission, the United States Securities and Exchange Commission (Form 40-F) and other regulatory authorities.