Aplite
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Aplite is a fine to very fine-grained sugary-textured rock of granite composition. It is composed of orthoclase and sodic plagioclase, mica and quartz with minor amounts of garnet and tourmaline. Aplite is believed to form via rapid crystallization of granitic magma saturated with dissolved superheated water and volatiles expanding into fractured rock. Most aplite bodies form veins called dikes a few centimetres to meters in thickness. Some aplite occurrences are associated with economic ores of tin and tungsten.