Definition
It is a metamorphic magnesium rich rock because it is composed of the mineral talc
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
USA
Tonale, Italy
Discoverer
Unknown
Unknown
Etymology
From 17th century, because of its greasy feel and use like a soap
From Trondheim, Norway
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft 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