It ils perfectly legal to prospect as long as it has noy been legaly withdrawn from mineral entry, such as a wilderness area. However around abanded buildings it gets tricky as much of colorados areas could technically be archeological sites. I always call Denver and seek their blessing as they are the regional office. They also send you the prospecting laws. I have found the Denver Office to be friendly, truthful and helpful. I have them fax me claim papers all the time to make sure I am not on somebodies claim. I think they charge me .15 cents a page. Its the homegrown personel they hire in their branch offices as receptionists and such I have trouble with. They try to make up there own laws at the receptionists desk. I have yet to run into a forest ranger that was a jerk. I did have one call his home office as he was incorrect in what he was stating, He did. I wave at him every time I see him. He waves back.