This new resource estimate represents an increase of approximately 329 million tonnes of ore from
the previous resource estimate as of December 31, 2007. The new Mineral Resource has been included in the scope of a pre-feasibility study to evaluate expansion options for Antamina, scheduled for completion by the end of this year.
Table 1: Estimate of Antamina Mineral Resource as at July 1, 2008 (inclusive of reserves)
| Classification | Ore (Mtonnes) | Cu (%) | Zn (%) | Ag (g/t) | Mo (%) |
| Measured Copper Ores | 130 | 0.98 | 0.16 | 7.7 | 0.04 |
| Measured Copper Zinc Ores | 56 | 0.86 | 1.92 | 16.9 | 0.01 |
| Indicated Copper Ores | 581 | 1 | 0.16 | 9.3 | 0.03 |
| Indicated Copper Zinc Ores | 170 | 1.05 | 1.99 | 17.5 | 0.01 |
| Inferred Copper Ores | 489 | 0.83 | 0.13 | 9.7 | 0.02 |
| Inferred Copper Zinc Ores | 96 | 0.86 | 1.62 | 15.9 | 0.01 |
| Total Resource | 1,521 | 0.93 | 0.51 | 10.9 | 0.02 |
Table 2: Previous estimate of Antamina Mineral Resource as at January 1, 2008
(inclusive of reserves)
| Classification | Ore | Cu (%) | Zn (%) | Ag (g/t) | Mo (%) |
| (Mtonnes) | |||||
| Measured Copper Ores | 78 | 0.91 | 0.17 | 7.3 | 0.04 |
| Measured Copper Zinc Ores | 44 | 0.85 | 2.32 | 17.8 | 0.02 |
| Indicated Copper Ores | 415 | 1.04 | 0.15 | 9.5 | 0.03 |
| Indicated Copper Zinc Ores | 143 | 1.11 | 2.54 | 18 | 0.01 |
| Inferred Copper Ores | 470 | 0.93 | 0.1 | 11.8 | 0.03 |
| Inferred Copper Zinc Ores | 43 | 0.91 | 1.97 | 18.1 | 0.01 |
| Total Resource | 1,192 | 0.98 | 0.56 | 11.9 | 0.03 |
The following tables show the Resource Estimate exclusive of reserves.
Table 3. Estimate of Antamina Mineral Resource as at July 1, 2008 (exclusive of reserves)
| Classification | Ore (Mtonnes) | Cu (%) | Zn (%) | Ag (g/t) | Mo (%) |
| Measured Copper Ores | 91 | 0.9 | 0.14 | 7.12 | 0.04 |
| Measured Copper Zinc Ores | 31 | 0.67 | 1.01 | 12.57 | 0.01 |
| Indicated Copper Ores | 328 | 0.92 | 0.17 | 8.93 | 0.02 |
| Indicated Copper Zinc Ores | 85 | 0.96 | 1.32 | 15.92 | 0.01 |
| Inferred Copper Ores | 489 | 0.83 | 0.13 | 9.7 | 0.02 |
| Inferred Copper Zinc Ores | 96 | 0.86 | 1.62 | 15.9 | 0.01 |
| Total Resources | 1,119 | 0.87 | 0.39 | 10.4 | 0.02 |
Table 4: Previous estimate of Antamina Mineral Resource as at January 1, 2008 (exclusive of
reserves)
| Classification | Ore | Cu (%) | Zn (%) | Ag (g/t) | Mo (%) |
| (Mtonnes) | |||||
| Measured Copper Mineral | 32 | 0.5 | 0.13 | 4.8 | 0.04 |
| Measured Copper Zinc Mineral | 16 | 0.47 | 0.87 | 9.7 | 0.04 |
| Indicated Copper Mineral | 158 | 0.94 | 0.15 | 9.1 | 0.03 |
| Indicated Copper Zinc Mineral | 56 | 1.06 | 2.33 | 16.2 | 0.01 |
| Inferred Copper Mineral | 470 | 0.93 | 0.1 | 11.8 | 0.02 |
| Inferred Copper Zinc Mineral | 43 | 0.91 | 1.97 | 18.1 | 0.01 |
| Total Resources | 774 | 0.91 | 0.39 | 11.6 | 0.02 |
Antamina continues with pit optimization activities that will result in the publication of revised reserves later this year, and continues to drill the ore body in an effort to expand the resource and increase the quality of available information within the recently developed resource shell.
Compañía Minera Antamina is a joint venture company held indirectly as to 33.75% by BHP Billiton Ltd., 33.75% by Xstrata Copper, 22.5% by Teck Cominco Limited and 10% by Mitsubishi Corporation.
The information in the report to which this statement is attached that relates to Mineral Resources is based on information compiled by Jhon Espinoza, who is a Member of The Australasian Institute of Mining and Metallurgy. Jhon Espinoza is a full-time employee of the Compañia Minera Antamina, the operating entity of Antamina. Jhon Espinoza has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the 2004 Edition of the ‘Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves’. Jhon Espinoza consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.
For additional information, please contact:
Gonzalo Quijandría, Corporate Affairs Manager.
Telephone: 511-217-3092 Fax: 511-217-3095
Email: gquijandria@antamina.com