Graywacke

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graywacke

[′grā‚wak·ə]
(petrology)
An argillaceous sandstone characterized by an abundance of unstable mineral and rock fragments and a fine-grained clay matrix binding the larger, sand-size detrital fragments.

Graywacke

 

a rock of sedimentary origin consisting of small fragments (grains) of sedimentary and chiefly metamorphic and igneous rock with an admixture of fragments of basic volcanic rock and tufogenic material. A significant quantity of cementing material is characteristic. The color is usually dark gray, black, or dark green (owing to the chlorite in the cement). The fragmentary grains in the graywacke are angular or slightly rounded and are poorly sorted. Graywackes are typical for geosynclinal areas where they form thick strata originating during periods of the rapid accumulation of disintegration products from internal uplifts composed of more ancient rock.

References in periodicals archive ?
Judd also makes superb sauvignon blanc and pinot noir under the Greywacke label.
Rates and processes of mineral weathering in soils developed on greywackes and shales in the southern uplands of Scotland.
Tectonically deformed sand volcanoes in a Precambrian greywacke, Northern Territory of Australia.
The soil at the location was a Pawson silt loam (colluvium variant) (Trangmar 1986) consisting of imperfectly drained loess derived from greywacke with evidence of a clay-enriched B horizon (Hewitt 1998).
This is further supported by the plot of samples outside and above the field of Franscisian greywacke on the Si.
Rapid growth is pushing new plantings onto adjacent hillsides that are underlain by greywacke, schist, and (less commonly) limestone.
anomalies overlie fine to coarse-grained massive greywacke sandstones and
The first 'bearing' layer consisted mainly of limestone; the second 'binder' course primarily greywacke and moraline--while the final 'wearing' layer was made up of diabase moraline, known for its resistance to anti-icing agents.
Principal sources of building stone in Scotland include Carboniferous and Devonian sandstones and flagstones (thinly bedded sandstones used for pavement and roofs) of the Midland Valley; Lower Palaeozoic greywacke sandstones, red sandstones, and granites of southern Scotland; and Palaeozoic to Mesozoic sandstones, Proterozoic to Palaeozoic granites and metamorphic rocks of the Highlands and Islands (e.
And beneath the Greywacke Arch, a street musician was playing plaintive standards on his alto saxophone, lending the sense of a Woody Allen soundtrack to the day.
Drilling intersected sediments with minor silicic alteration and few quartz veins in a greywacke host rock.
Old Bridge Cellars is a leading sales, marketing and import company based in Napa, California, recognized for its collection of regional estates including d'Arenberg, John Duval, Greywacke, Kilikanoon, Jasper Hill, Cullen, Shoofly, Stickybeak and Frisk.