Riggins Group, Orofino series, and related rocks.

Metasedimentary and metavolcanic schist, gneiss, amphibolite, and marble, all of uncertain age, along eastern margin of island-arc complex; typically hornblende-rich. Includes Pollock Mountain amphibolite southeast of Riggins and gneiss of Swiftwater Creek near Lowell. (Mesozoic-Paleozoic Rocks of the Blue Mountains Island-Arc Complex).
State Idaho
Name Riggins Group, Orofino series, and related rocks.
Geologic age Cretaceous to Permian
Lithologic constituents
Major
Metamorphic > GneissMetasedimentary and metavolcanic; typically hornblende-rich.
Metamorphic > SchistMetasedimentary and metavolcanic; typically hornblende-rich.
Metamorphic > AmphiboliteMetasedimentary and metavolcanic; typically hornblende-rich.
Minor
Metamorphic > Metasedimentary > Metacarbonate > Marble
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 Adams - Clearwater - Idaho - Nez Perce