cpendola,
There is placer gold to be found in the San Miguel. Not too sure about detecting for nuggets, but there are folks washing gravel west of Telluride near Placerville.
All through out the San Juan mtns there are ghost towns and old mining camps that are fun to explore. Be careful metal detecting these sites though. It is illegal to remove artifacts from the National Forest.
Pretty area and not commercialized except for in Telluride.
Enjoy,
3xflyfisher