Lower Prichard Formation

Dark and light gray, pyrite- and pyrrhotite-rich siltite and argillite in planar couplets with subordinate gray, flat-laminated, fine-grained quartzite.
State Montana
Name Lower Prichard Formation
Geologic age Middle Proterozoic
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Metasiltstonesiltite
Metamorphic > Metasedimentary > Metaclastic > Argillite
Minor
Metamorphic > Metasedimentary > Metaclastic > Quartzite
References

Vuke, S.M., Porter, K.W., Lonn, J.D., and Lopez, D.A., 2007, Geologic Map of Montana - Compact Disc: Montana Bureau of Mines and Geology: Geologic Map 62-C, 73 p., 2 sheets, scale 1:500,000. This map was digitized in 2012 as a result of a contract between the U.S. Geological Survey and the Montana Bureau of Mines and Geology.

NGMDB product
Counties Lake - Lincoln - Missoula - Sanders