Definition of graywacke in English:


(British greywacke)


  • A dark coarse-grained sandstone containing more than 15 percent clay.

    • ‘The builders used greywacke from the Rangitata River and limestone brought from Mount Somers and shaped the rocks by hand.’
    • ‘The Southern Highland Group, consisting of greywacke, shale, limestone and volcanic rock, forms the top of the Dalradian succession.’
    • ‘Geologically the axes from the New Guinea Highlands comprise thermally metamorphosed basalt, chert and greywacke depending on quarry source.’
    • ‘The rocks typically comprise a monotonous sequence of greywackes, reddish-weathering arkosic sandstones, shales and subordinate conglomerates.’
    • ‘Higher vapour pressures would be generated in sediments of low permeability, such as mudstones, which would account for sills being more commonly found in shale and greywacke.’


Late 18th century (as grauwacke): from German Grauwacke, from grau ‘gray’ + wacke. The anglicized form dates from the early 19th century.