greywacke

/ ˈɡreɪˌwækə /

noun

1. any dark sandstone or grit having a matrix of clay minerals

Word History and Origins

Origin of greywacke¹

C19: partial translation of German Grauwacke; see wacke

Example Sentences

In Cornwall and Devonshire, the lead ore is found in veins in killas, a clay-slate passing into greywacke.

From Project Gutenberg

The date assigned to its upheaval is "after the unfossiliferous greywacke, or Cambrian strata, and before the Silurian."

From Project Gutenberg

This fossil-bearing set of strata he first styled the “fossiliferous greywacke series,” changing it in 1835 to “Silurian system.”

From Project Gutenberg