Definition
It is a metamorphic magnesium rich rock because it is composed of the mineral talc
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
History
Origin
USA
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Discoverer
Unknown
Unknown
Etymology
From 17th century, because of its greasy feel and use like a soap
From German Grauwacke, from grau grey + wacke
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Family
Group
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Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock