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                                                                    EXHIBIT 12.1

                                  CERTIFICATION

      I, Richard J. Hall, certify that:

1. I have reviewed this annual report on Form 20-F of Metallica Resources Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a
material fact or omit to state a material fact necessary to make the statements
made, in light of the circumstances under which such statements were made, not
misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material respects the
financial condition, results of operations and cash flows of the company as of,
and for, the periods presented in this report;

4. The company's other certifying officer and I are responsible for establishing
and maintaining disclosure controls and procedures (as defined in Exchange Act
Rules 13a-15(e) and 15d-15(e)) [omitted pursuant to Transition Period provisions
at Section III of Release 34-47986 of the Securities and Exchange Commission
entitled "Management's Reports on Internal Control over Financial Reporting and
Certification of Disclosure in Exchange Act Periodic Reports"] for the company
and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure
controls and procedures to be designed under our supervision, to ensure that
material information relating to the company, including its consolidated
subsidiaries, is made known to us by others within those entities, particularly
during the period in which this report is being prepared;

(b) [omitted pursuant to Transition Period provisions at Section III of Release
34-47986 of the Securities and Exchange Commission entitled "Management's
Reports on Internal Control over Financial Reporting and Certification of
Disclosure in Exchange Act Periodic Reports"];

(c) Evaluated the effectiveness of the company's disclosure controls and
procedures and presented in this report our conclusions about the effectiveness
of the disclosure controls and procedures, as of the end of the period covered
by this report based on such evaluation; and

(d) Disclosed in this report any change in the company's internal control over
financial reporting that occurred during the period covered by the annual report
that has materially affected, or is reasonably likely to materially affect, the
company's internal control over financial reporting; and

5. The company's other certifying officer and I have disclosed, based on our
most recent evaluation of internal control over financial reporting, to the
company's auditors and the audit committee of the company's board of directors
(or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or
operation of internal control over financial reporting which are reasonably
likely to adversely affect the company's ability to record, process, summarize
and report financial information; and

(b) Any fraud, whether or not material, that involves management or other
employees who have a significant role in the company's internal control over
financial reporting.

Date: March 30, 2005

/s/ Richard J. Hall
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Richard J. Hall, President and Chief Executive Officer