Definition
Anthracite is a type of sedimentary rock which is hard and is variety of coal that has high luster
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
History
Origin
Pennsylvania, U.S.
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Discoverer
Unknown
Unknown
Etymology
From Greek anthrakites, from anthrax, anthrak meaning coal
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
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock