What is "trondhjemite"

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.

Trondhjemite is common in Archean terranes occurring in conjunction with tonalite and granodiorite as the TTG ( tonalite-trondhjemite-granodiorite) ortho gneiss suite. Trondhjemite dikes also commonly form part of the sheeted dike complex of an ophiolite.