Definition
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
Trondhjemite is a leucocratic (light-colored) intrusive igneous rock. It is a variety of tonalite in which the plagioclase is mostly in the form of oligoclase. Trondhjemites are sometimes known as plagiogranites.
History
Origin
-
Tonale, Italy
Discoverer
Unknown
Unknown
Etymology
From German Grauwacke, from grau grey + wacke
From Trondheim, Norway
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Family
Group
-
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock