 This makes it the oldest recognised intrusive rock on the Earth, containing the oldest known igneous textures and mineral assemblages.Metasedimentary rocks from within the Narryer Gneiss terrane account for about 10% of the outcrop and are variably deformed but uniformly of at least amphibolite grade metamorphism.The most abundant rock types are quartzite and banded iron formation, with subordinate metamorphic gneisses, metaconglomerates and pelitic to semi-pelitic quartz-muscovite schists.