quartz graywacke

quartz graywacke

[′kwȯrts ′grā‚wak·ə]
(petrology)
A graywacke containing abundant grains of quartz and chert and less than 10% each of feldspars and rock fragments.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.