HOLA amigos,
Check with the BLM office that has records of current mining claims, for while there are indeed miles of placer creeks in the Black Hills which are open and unclaimed, there are some active claims here and there; to go detecting or panning on someone else's claim without their permission is breaking the law. There are also many parcels of privately owned land along the creeks, and you need permission of the owners before going onto their land. Get a Forest Service map (for starters) of the Black Hills National Forest, these don't have good details on topography, but do show what areas are public lands and what are private. <
Know where you are on that map too, or mistakes can lead to misunderstandings.> One of the best placer areas in the Black Hills for coarse gold is Rockerville, and almost every foot of it is private ground, the tiny bit that is on public lands is under active claims. Don't assume that since you don't see someone there working on it that it is not under claim either. Just do a little research on where you CAN legally go, and you won't have problems with the law or angry claim-owners, landowners etc.
The Black Hills are
not known for being nugget-heaven, nevertheless some nice ones
have been found; the "official" record is a 22 and a half ouncer found by Doc Wing back in 1879 but there were much larger ones which were found before the "official" record started, such as $3,500 nugget largest yet found in the Black Hills reported headlines for Deadwood, Jul 01 1876 figuring the value at $16 per ounce, or the 11 lb. nugget found by John W. Allen on No 1 above Discovery (Deadwood) on Jun 13 1878 and some impressive ones are still found today - but people don't talk about them.
Good luck and good hunting, be prepared for plenty of "hot rocks" and high mineralization when nugget shooting in the Black Hills, and DO come and post some photos of the huge nuggets you will find!

Oroblanco