is a very coarse-grained, intrusive (intrusive means it is squeezed between other rocks) igneous rock composed of grains usually larger than 2.5 cm (1 inch) in size; such rocks are referred to as pegmatitic.

Most pegmatites are composed of quartz, feldspar and mica; in essence a granite.

Crystal size is the most striking feature of pegmatites, with crystals often over 5 cm in size. Individual crystals over 10 meters across have been found, and some of the world's largest crystals are found within pegmatites.

Similarly, crystal texture and form within pegmatitic rock may be taken to extreme size and perfection. .





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