Prichard Formation.

Siltite, quartzite, and argillite in northern Idaho; deposited in deep water and contains voluminous ~1470 Ma mafic sills. Includes siltite, quartzite, fine-grained schist, and carbonate rocks structurally above anorthosite near Boehls Butte, northeast of Elk River. (Mesoproterozoic Belt Supergroup).
State Idaho
Name Prichard Formation.
Geologic age Mesoproterozoic
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Argillite
Metamorphic > Metasedimentary > Metaclastic > Quartzite
Metamorphic > Metasedimentary > Metaclastic > MetasiltstoneSiltite.
Minor
Metamorphic > SchistFine-grained schist.
Sedimentary > CarbonateCarbonate rocks structurally above anorthosite near Boehls Butte.
References

Lewis, Reed S., Link, Paul K., Stanford, Loudon R., and Long, Sean P., Geologic Map of Idaho, 2012, Idaho Geological Survey, Geologic Map 9 (M-9); Scale 1:500,000.

NGMDB product
Counties Benewah - Bonner - Boundary - Clearwater - Kootenai - Shoshone