Colorado is second only to California in the variety of minerals it has within its boundaries. The state has over thirty varieties of gems. There are many opportunities for mineral collecting, but a person must be careful when evaluating a collecting site. A given mineral locality may actually be a staked claim. Collecting from such a site without permission is legally considered theft. Access to, and through, private land must be granted by the landowner prior to use. Please be aware of all federal, state, and local laws; and be sensitive to the landowners wishes.
Joining a local gem and mineral club is an excellent way to go collecting on club-sponsored field trips and/or club-owned claims. See the RockTalk right-sidebar for links to many resources including many gem and mineral clubs around the state.
Determining the land status is one of the most important parts of prospecting. Specific county governments can provide more specific information on land ownership. Prospecting in Colorado should not be done on private lands without consent of the property owner. Prospecting on federal land is regulated by the BLM and U.S. Forest Service. The Bureau of Land Management Mining and Minerals section and the Colorado Division of Reclamation, Mining, and Safety can answer questions about staking claims, mine permitting, and other information about land status.
Colorado Division of Reclamation, Mining, and Safety — comprehensive information on mining programs and regulations for the state.
US Department of the Interior – Bureau of Land Management – Mining and Minerals — Mineral prospecting and development information, and specifically how to establish a mining claim; Mining Claims and Sites on Federal Lands; and their Mining Claim Packet.