The diffrence between pantented and unpatented is wrapped up in the following sentence If you have staked out an unpatented mining claim you do not have the right to the surface. No building allowed, if there is an abandoned building you can not use it, even if it is on your claim.
"Your right is restricted to the development and extraction of a mineral deposit. The surface of an unpatented mining claim is NOT private property. If you staked a mining claim on National Forest System lands, ownership remains federal lands administered by the Forest Service."information copied from USDA
Can I camp on my unpatented mining claim?
All users of our National Forests have the opportunity to camp within time limitations established by the Forest on which you are operating. Camping on your unpatented mining claim beyond those limits must be reasonably incidental to locatable mineral activities, and may require an approved plan of operations if cumulative impacts result in a significant surface disturbance. Consult with the local Ranger District prior to any occupancy on your mining claim.
Can I construct buildings or other improvements on my unpatented mining claim?
You may not construct, place, or maintain any kind of building or other structure, road, trail, fence or enclosure, and place or store equipment without the prior approval of a plan of operation from the Forest Service. Prospecting and exploration activities usually do not justify the use of such structures. Unpatented Mining Claims Forest Service
Who can stake a mining claim?
A person who is a citizen of the United States or has declared an intention to become a citizen may locate and hold a mining claim. You may prospect and locate mining claims on lands open to mineral entry.
What is a mining claim?
A mining claim is a selected parcel of Federal land, valuable for a specific mineral deposit, for which you have asserted a right of possession under the General Mining Law. Your right is restricted to the development and extraction of a mineral deposit. The surface of an unpatented mining claim is NOT private property. If you staked a mining claim on National Forest System lands, ownership remains federal lands administered by the Forest Service. The Forest Service has the right to manage the surface and surface resources on an unpatented mining claim. This includes public use and access on and across lands covered by an unpatented mining claim as long as the use does not endanger or materially interfere with uses that are required for and resaonably incident to mining.
How is the surface managed on unpatented mining claims?
Exploration and mining activities are administered by the Forest Service by regulations of the Secretary of Agriculture contained in 36 CFR 228 Part A. These regulations require that if your proposed operation could likely cause “significant disturbance of surface resources” you must submit a plan of operations. Contact your local USFS Ranger District Office for information on any of your proposed activities.
Can I use previously abandoned buildings and equipment left on my unpatented mining claim?
Once an unpatented claim is abandoned, ownership of buildings, structures, equipment, artifacts, etc. becomes property of the United States. Removal or use of such property requires Forest Service authorization. May 2015
information from -https://www.fs.fed.us/