(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).

(b) A determination under paragraph (a) of this section shall be based upon the following:   (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.