greywacke

== English == === Alternative forms === graywacke === Etymology === Anglicised form of grauwacke. === Pronunciation === (UK) IPA(key): /ˈɡɹeɪ.wak.ə/ (GS) IPA(key): /ˈɡɹeɪ.wæk/ === Noun === greywacke (countable and uncountable, plural greywackes) (geology) A hard dark sandstone with poorly sorted angular grains of quartz, feldspar, and small rock fragments in a compact, clay-fine matrix. ==== Derived terms ==== ==== Translations ====