Gneiss is a widely distributed medium- to coarse-grained metamorphic rock that exhibits distinctive banding that can best be observed in massive exposed samples, such as those found in Stone Mountain, Georgia. The characteristic alternation of dark and light coloration in gneisses is typically an indication of differing proportions of constituent minerals, although this can also be the result of varying grain sizes. Gneisses also display well-developed foliation, but unlike schists, split in irregular patterns rather than along planes. Similar to granite, gneiss is often used as a building or paving stone. As its name implies, granitoid gneiss is a variety of gneiss that exhibits many of the properties characteristic of granite. Notable examples of granitoid gneiss can be found in Columbus, Georgia and in South Africa.
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