any dark sandstone or grit having a matrix of clay minerals
Word origin
C19: partial translation of German Grauwacke; see wacke
Examples of 'greywacke' in a sentence
greywacke
The investigated sandstones belong to the greywacke group.
R.R. Khasanov, A.I. Mullakaev, E.N. Dusmanov 2017, 'The Structure of Sandstones in Productive Horizons of the Permian Bituminous Depositsof Tatarstan (Russia)', Učënye Zapiski Kazanskogo Universiteta. Seriâ Estestvennye Naukihttp://kpfu.ru/portal/docs/F1891911906/159_1_est_11.pdf. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)