This used to be an exploited loophole. Wealthy people would use inexpensive "mineral exploration" leases to get long-term control of areas of Federal land that

This used to be an exploited loophole. Wealthy people would use inexpensive "mineral exploration" leases to get long-term control of areas of Federal land that they wanted to use for other purposes. The only real cost was maintaining the bare minimum fiction that they were doing mineral exploration -- dig the occasional hole in some corner of the property, move a bit of dirt around. Meanwhile, they were doing all kinds of other personal things with the land and building structures enabled by having the lease. The US DoI started clamping down on the use of fake mineral leases a few decades ago and put policies in place to strongly discourage this kind of abuse.