Understanding AML

diagram of underground mine
Abandoned mineral lands (AML) are lands, waters, and surrounding watersheds that contain facilities, structures, improvements, and disturbances associated with past mineral exploration, extraction, processing, and transportation, including oil and gas features and operations, for which the NPS takes action under various authorities to mitigate, reclaim, or restore in order to reduce hazards and impacts to resources.

Not surprisingly, the legacy of abandoned mineral lands spans North America. Long before the arrival of Europeans, American Indians mined flint, obsidian, and native copper for tools and weapons, turquoise and other stones for jewelry, and clay for pots and pipes. During the 16th century, the lure of gold and the prospect of great wealth drove Spanish explorers into North and South America. Later gold rushes and "Manifest Destiny" were responsible for Europeans settling much of the western United States. The industrial age of the 19th and 20th centuries introduced large-scale extraction of mineral resources such as coal, copper, and iron, oil, gas, and uranium, leaving significant environmental impacts on the land. Deserted, these sites now stand in silent testimony to those who pioneered this country in search of mineral wealth.

Historically, companies and individuals explored for and extracted a wide variety of metals, minerals, fossil fuels, and mineral materials from lands that are now part of the National Park System. Precious metals such as gold, silver, and platinum;and base metals such as copper, lead, and zinc have been extracted. Industrial minerals such as talc, limestone, and borates;building stone;and aggregate materials such as sand and gravel have also been mined. Coal mining and oil and gas development have also occurred in parks. Sites often have waste rock piles (unprocessed, sub-grade mined rock), tailings (mined rock that has been processed to remove the desired commodities), abandoned roads, fuel storage tanks, drainage diversions, buildings such as mills and assay shops, deteriorating structures such as headframes and tramways, and abandoned heavy equipment. Abandoned mineral sites and features are remnants of a time when operators were not required by federal or state laws and regulations to perform reclamation. Now, reclamation is required by agency regulations that implement federal and state laws.

Last updated: December 16, 2015