OPINION — AG — THE STATE DEPARTMENT OF MINES IS WITHOUT AUTHORITY TO ACCEPT A LETTER OF CREDIT IN SATISFACTION OF THE PERFORMANCE BOND REQUIREMENT SET FORTH IN 45 O.S. 1979 Supp., 745.6 [45-745.6] (STATE DEPARTMENT OF MINES, RECLAMATION OF MINING LANDS, SURFACE COAL MINING, BOND, LICENSED) CITE: 45 O.S. 1979 Supp., 745.6 [45-745.6] (BRENT S. HAYNIE)