@misc{indiciae6bf5c47d40d7,
  title = {Chemical compositions of rock types as factors in our environment},
  author = {Harry A. Tourtelot},
  year = {1971},
  doi = {10.1130/mem123-p13},
  url = {https://pubs.usgs.gov/publication/70227310},
  note = {Source identifier: 70227310}
}