From the Document: "Federal lands, which comprise one-third of the lands in the U.S., are a major source of hardrock minerals, such as gold, silver, and copper. There were 748 authorized hardrock mining operations on federal lands, as of September 2018. Hardrock minerals play a major role in the U.S. and global economies and are widely used, including in smartphones and electric engines. However, mining hardrock minerals can create public health, safety, and environmental hazards. Questions have been raised about whether the systems used to manage hardrock mining on public lands adequately serve the nation's interests."
Government Accountability Office: http://www.gao.gov/