Mineral Resources On-Line Spatial Data
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Geologic units containing graywache
...a dark gray, firmly indurated, coarse-grained sandstone that consists of poorly sorted angular to subangular grains of quartz and feldspar, with a variety of dark rock and mineral fragments embedded in a compact clayey matrix having the general composition of slate and containing an abundance of very fine-grained illite, sericite, and chloritic minerals.
This category is also used for graywache.
- Metavolcanic and metasedimentary rocks; Jurassic greenschist-facies metamorphic rocks; western Idaho, Blue Mountains island-arc complex (Jurassic)
- Jurassic mixed marine detrital and volcanic rocks of western Idaho.