@misc{indiciae1eedbf3c39d0,
  title = {Geochemical analyses of rock samples collected at the Penn Mine, Calaveras County, California},
  author = {J.A. Peterson},
  year = {1985},
  doi = {10.3133/ofr85588},
  url = {https://pubs.usgs.gov/publication/ofr85588},
  note = {Source identifier: ofr85588}
}