Definition
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
Litchfieldite is a rare igneous rock which is coarse-grained, foliated and a variety of nepheline syenite, sometimes also called as nepheline syenite gneiss or gneissic nepeheline syenite
History
Origin
-
USA
Discoverer
Unknown
Bayley
Etymology
From German Grauwacke, from grau grey + wacke
From its occurrence at Litchfield, Maine, USA
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
-
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock