The tronhjemite is a plutonic rock composed of quartz and plagioclase with minor amounts of biotite, the trondhjemitas being formed at great depths in the earth's crust, the trondhjemita is a "leucotonalite" (dominated by clear minerals) and is Consider a special variety of tonalite characterized by no hornblende.
It is extracted from quarries for use as ornamental rock and is sold as "white granite." The name of the rock was coined by Victor Goldschmidt in 1916 and refers to the Norwegian city of Trondheim.
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