They are represented by gneiss, mica schists, and amphibolite. Garnet is also sourced commonly from metamorphic rocks, such as amphibolite schists. The graptolite-bearing shales were later metamorphosed into lower amphibolite facies slates. Oligoclase is also found in metamorphic rocks formed under transitional greenschist to amphibolite facies conditions. Rocks typical of the region include schist, amphibolite, gneiss, migmatite, and granite. Under pressure-metamorphism hornblende is developed and various types of amphibolite and hornblende-schist are produced. Some show granulite facies metamorphism, but most are the slightly lower temperature amphibolite facies. These rocks are frequently metamorphosed greenschist, amphibolite, and granulite facies. It occurs in hydrothermal veins, in basalt vesicles, skarns, amphibolite and serpentinite. Metamorphic rocks such as schists, marbles, and amphibolite are also widely found. One is a mafic unit with gabbro, norite, amphibolite and anorthosite. Some restricted occurrences of amphibolite and ultramafic rocks are also present. They have been metamorphosed to greenschist or low grade amphibolite. However, caution must be applied here before embarking on metamorphic mapping based on amphibolite alone. Eclogite may completely retrogress to amphibolite or granulite during exhumation.