@misc{indiciae673190e1a1d5,
  title = {Mineral Commodity Summaries 2006},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {2006},
  doi = {10.3133/mineral2006},
  url = {https://pubs.usgs.gov/publication/mineral2006},
  note = {Source identifier: mineral2006}
}