<ARTICLE> 5 <LEGEND> This schedule contains summary financial information extracted from the Condensed Consolidated Balance Sheet at June 30, 1997 and the related Condensed Statement of Consolidated Operations for the six months ended June 30, 1997 and is qualified in its entirety by reference to such financial statements. </LEGEND> <MULTIPLIER> 1,000 <PERIOD-TYPE> 3-MOS <FISCAL-YEAR-END> DEC-31-1997 <PERIOD-END> JUN-30-1997 <CASH> 87,840 <SECURITIES> 163,788 <RECEIVABLES> 37,789 <ALLOWANCES> 0 <INVENTORY> 88,579 <CURRENT-ASSETS> 395,701 <PP&E> 2,016,633 <DEPRECIATION> 1,022,514 <TOTAL-ASSETS> 1,471,988 <CURRENT-LIABILITIES> 103,735 <BONDS> 188,730 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 146,728 <OTHER-SE> 614,265 <TOTAL-LIABILITY-AND-EQUITY> 1,471,988 <SALES> 338,460 <TOTAL-REVENUES> 418,846 <CGS> 295,448<F1> <TOTAL-COSTS> 314,942<F2> <OTHER-EXPENSES> 25,440<F3> <LOSS-PROVISION> 0 <INTEREST-EXPENSE> 5,433 <INCOME-PRETAX> 73,031 <INCOME-TAX> 33,244 <INCOME-CONTINUING> 33,638 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 33,638 <EPS-PRIMARY> 0.23 <EPS-DILUTED> 0 <FN> <F1> Includes Production costs and Depreciation, depletion and amortization from Condensed Statement of Consolidated Operations. <F2> Incluees Production costs and Depreciation, depletion and amortization and Administrative and general expense from Condensed Statement of Consolidated Operations. <F3> Includes Exploration expense and Other expense from Condensed Statement of Consolidated Operations. </FN>