250.1603—Determination of sulphur deposit.
        
        (a) 
         Upon receipt of a written request from the lessee, the District Manager will determine whether a sulphur deposit has been defined that contains sulphur in paying quantities (i.e., sulphur in quantities sufficient to yield a return in excess of the costs, after completion of the wells, of producing minerals at the wellheads).
    
    
    
        
        (1) 
         Core analyses that indicate the presence of a producible sulphur deposit (including an assay of elemental sulphur);
    
    
        
        (2) 
         An estimate of the amount of recoverable sulphur in long tons over a specified period of time; and
    
    
        
        (3) 
         Contour map of the cap rock together with isopach map showing the extent and estimated thickness of the sulphur deposit.