noun gray·wacke \ˈgrā-ˌwak, -ˌwa-kə\

Definition of graywacke

  1. :  a coarse usually dark gray sandstone or fine-grained conglomerate composed of firmly cemented fragments (as of quartz or feldspar)

Origin and Etymology of graywacke

partial translation of German Grauwacke

First Known Use: 1805

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