Mining of hardrock minerals on federal lands is governed primarily by the General Mining Law of 1872. The original purposes of the Mining Law were to promote mineral exploration and development on federal lands in the western United States, offer an opportunity to obtain a clear title to mines already being worked, and help settle the West. The Mining Law grants free access to individuals and corporations to prospect for minerals on open public domain lands, and allows them, upon making a discovery, to stake (or "locate") a claim on the deposit. A valid claim entitles the holder to develop the minerals. The 1872 Mining Law originally applied to all valuable mineral deposits except coal (17 Stat. 91, 1872, as amended). Public domain lands are those retained under federal ownership since their original acquisition by treaty, cession, or purchase as part of the general territory of the United States, including lands that passed out of but reverted back to federal ownership. "Acquired" lands—those obtained from a state or a private owner through purchase, gift, or condemnation for particular federal purposes rather than as general territory of the United States—are subject to leasing only and are not covered by the 1872 Law. Some public lands may be "withdrawn" or closed to mineral entry. The 1872 Mining Law was one of the primary forces behind the development of mineral resources in the West, along with the industries and services that supported mineral production. Major hardrock minerals developed in the West include copper, silver, gold, lead, zinc, molybdenum, and uranium. During the 19 th century, major mining districts for silver and gold were developed under the Mining Law in Colorado, California, Idaho, and Nevada. Early in the 20 th century, there were major developments of porphyry copper in Arizona. Large molybdenum and tungsten deposits in Colorado were also developed. The Mining Law continues to provide the structure for much of the western mineral development on public domain lands. Western mining, although not as extensive as it once was, is still a major economic activity, and a high percentage of hardrock mining is on public lands. After a prospector has conducted exploration work on public domain land, he or she may locate a claim to an area believed to contain a valuable mineral. To hold a claim on public land, claimants must pay an annual maintenance fee of $125 per claim. Claimants with 10 claims or fewer may file for a waiver of the annual maintenance fee and perform the annual assessment work instead. There also is a $30 fee for first-time locators to locate and record a claim. The fees above are to be adjusted every five years based on the Consumer Price Index (30 U.S.C. 28 j (c)). The last adjustment was made on September 1, 2004. Prior to 2004 the fees were $100 and $25 respectively. The annual maintenance fee replaces the requirement that $100 of annual development work be conducted per claim. The maintenance and location fees generated revenue estimated at $54.7 million in FY2007 and $39.0 million in FY2008, according to the Bureau of Land Management (BLM). Revenues from fees have fluctuated over the years and were $23.9 million in FY2000. Once a claimed mineral deposit is determined to be economically recoverable, and at least $500 of development work has been performed, the claim holder may file a patent application to obtain title to surface and mineral rights. Beginning January 3, 1989, a fee of $250 per patent application plus $50 per claim within each application has been required. If the patent application is approved, the claimant may purchase surface and mineral rights at a rate of $2.50 per acre for placer claims and $5 per acre for lode claims. A placer deposit is an alluvial deposit of valuable minerals usually in sand or gravel; a lode or vein deposit is of a valuable mineral consisting of quartz or other rock in place with definite boundaries. A placer claim is usually limited to 20 acres but a lode claim may be slightly greater than 20 acres. These per-acre fees were substantial when the Mining Law was enacted—claimed land and minerals now far exceed these amounts in value. The following provisions currently apply to claims: There is no limit on the number of claims a person can locate; There is no requirement that mineral production ever commence; Mineral production can take place without a patent or royalty payments to the federal government; and Claims can be held indefinitely with or without mineral production, subject to challenge if not developed. Most of the current mining activity and mineral claims under the Mining Law are in Nevada, Arizona, California, Montana, and Wyoming. As of the end of FY2005, approximately 35% of mining claims were in Nevada alone and another nearly 35% were in the other four states. According to the Bureau of Land Management, the number of active claims declined from about 1.2 million claims in FY1989 to 294,678 for FY1993. Many claims were dropped as a result of provisions of law charging a $100-per-claim annual maintenance fee. The number of active claims subsequently rose to 324,651 in FY1997, reflecting the relative strength of the gold and copper industries. The number of active claims fell to a low of 207,757 for FY2001, reflecting a decline in the gold and copper industries and, according to the BLM, changes in public land policy that significantly lengthened the time necessary to get permission to mine. Active claims stood at 207,241 in FY2005. Only a small percentage of claims is ever patented, totaling about 3.4 million acres from 1867 through 2006. This represents approximately 1.5% of all public lands patented; most public lands have been patented under homestead entries, statehood grants, railroad grants, and other non-mineral public land laws. It is not required to patent a claim to mine a deposit, and a great deal of mining activity is currently taking place on unpatented claims. However, patenting a claim gives the holder legal title to both the surface and the minerals, and relieves the holder of having to pay the annual fees. Beginning in FY1995, Congress has enacted (in the Interior appropriations laws) a series of one-year moratoria on the issuance of mineral patents. However, applications meeting certain requirements that were filed on or before September 30, 1994, are allowed to proceed, and third-party contractors are authorized to process the mineral examinations on those applications. The patent moratorium will not stop the production of valuable mineral resources from the public lands, but will prevent the further transfer of ownership of public lands to the private sector (with the exception of the 237 patent applications already in the pipeline). The annual one-year moratorium on patenting continues the uncertainty over whether efforts will continue to try to reform the 1872 Mining Law. The mining industry would like to end the uncertainty to facilitate its long-term business planning. Environmentalists, who were hoping for new environmental protection language in a major mining law reform bill, argue that the patent moratorium does not protect the environment from current mining practices. In 1920, the Mineral Leasing Act removed oil, gas, oil shale, phosphates, sodium, and certain other minerals on federal public domain lands from the claim-patent system of the 1872 Mining Law and set up a system of leasing in which the federal government retains ownership of the leased lands. Coal, which previously had its own claim-patent law (the 1873 Coal Act), was also included in the 1920 Leasing Act. After 1955, common variety minerals such as sand, stone, gravel, cinders, and pumice were sold under the Materials Act of 1947, as amended. A strong push for an all-leasing system developed during the 1930s and 1940s, but no such legislation was enacted. As mentioned, acquired federal lands were never subject to the General Mining Law. The Mineral Leasing Act for Acquired Lands of 1947 authorized the leasing of leasable minerals in some acquired federal lands. The Reorganization Plan No. 3 of 1946 and earlier acts authorized the leasing of hardrock minerals on acquired forest lands. During the 1960s and 1970s, the Multiple Use Sustained Yield Act, Wilderness Act, National Forest Management Act, National Environmental Policy Act (NEPA), and Federal Land Policy Management Act (FLPMA) addressed environmental protection, multiple use, and management of federal land generally. By imposing new requirements on agency actions, and by withdrawing some federal lands from development, these acts have affected mineral development under both the leasing system and the Mining Law claim-patent system. The Mining Law contains no direct environmental controls, but mining claims are subject to all general environmental laws as a precondition for development. The mining industry must comply with applicable requirements of the Clean Water and Clean Air Acts, state reclamation standards where they exist, and federal and state statutes relating to the handling and disposal of certain toxic wastes, among other laws. The evolving leasing system and later withdrawals of lands from hardrock exploration and development diminished the amount of lands under the Mining Law authority. For those hardrock minerals that remain under the Mining Law, however, the claim-patent system is essentially the same as it was when the law was enacted. Critics argue that the West is now developed and that the 1872 Mining Law is obsolete and inconsistent with other federal natural resource policies. Supporters maintain that the combination of leasing for some resources and a claim-patent system for others works well and should be maintained. The National Mining Association (NMA) states that the "existing law more than adequately meets the four criteria essential to any mineral tenure law": free and open access to explore for minerals on unappropriated public lands, exclusive exploration rights, the right to develop the valuable minerals discovered, and security of tenure.