Mining on Federal Lands: More Than 800 Operations Authorized to Mine and Total Mineral Production is Unknown [open pdf - 533KB]
From the Document: "You asked us to review mining on federal lands. This report identifies (1) the number of operations authorized to produce solid minerals on federal lands as of September 30, 2018, and selected characteristics of those operations, and (2) the federal royalties obtained from and quantity of solid minerals produced on federal lands for fiscal year 2018. We also have ongoing work examining hardrock mining systems and stakeholder views of the systems."
Government Accountability Office: https://www.gao.gov/