Geology. a dark-gray coarse-grained wacke.
Origin of graywacke
1805–15; partly translation, partly adapted from German Grauwache; see wacke
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for graywacke
Historical Examples of graywacke
We're sure to get the better of Graywacke, and why not anticipate?A Summer in Leslie Goldthwaite's Life.
Mrs. A. D. T. Whitney
Is it primitive, or is it graywacke like Catskill Mountains?
Any of various dark gray, coarse-grained sandstones that contain abundant feldspar and rock fragments and often have a clay-rich matrix. Graywackes are thought to originate in environments where erosion, transportation, and deposition happen so quickly that minerals and rock fragments do not have sufficient time to break down into finer constituents.
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