@misc{indiciae9b4d77463d27,
  title = {Geology and mineral paragenesis of the Pea Ridge iron ore mine, Washington County, Missouri: Origin of the rare-earth-element- and gold-bearing breccia pipes. Some mineralogical and geochemical aspects of middle and upper Pennsylvanian marine black shales in part of the midcontinent region. Mineralogical and geochemical analysis of the metal- and organic-rich Grassy Creek Shale of the New Albany group (Upper Devonian and Lower Mississippian) in Hardin County, southern Illinois},
  author = {L. M. Nuelle and Warren C. Day and Gary B. Sidder and Cheryl M. Seeger and George A. Desborough and Joseph R. Hatch and Joel S. Leventhal},
  year = {1992},
  doi = {10.3133/b1989ac},
  url = {https://pubs.usgs.gov/publication/b1989AC},
  note = {Source identifier: b1989AC}
}