43 C.F.R. § 3505.62 : Public Lands: Interior — REGULATIONS RELATING TO PUBLIC LANDS — BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR — MINERALS MANAGEMENT (3000) — LEASING OF SOLID MINERALS OTHER THAN COAL AND OIL SHALE — PROSPECTING PERMITS —PROSPECTING PERMIT TERMS AND CONDITIONS — Under what conditions will BLM extend my prospecting permit?

You must prove that:

(a) You explored with reasonable diligence and were unable to determine the existence and workability of a valuable deposit covered by the permit. Reasonable diligence means that, in BLM's opinion, you drilled a sufficient number of holes or performed other comparable prospecting to explore the permit area within the time allowed; or
(b) Your failure to perform diligent prospecting activities was due to conditions beyond your control.

43 C.F.R. §3505.62