Definition
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
Foidolite is a rare type of coarse-grained intrusive igneous rock with a feldspathoid mineral content greater than 60%
History
Origin
-
-
Discoverer
Unknown
Unknown
Etymology
From German Grauwacke, from grau grey + wacke
From the mineral feldspathoid which is the main content of rock
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Family
Group
-
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock