A pegmatite is an igneous rock with a very rough texture, which has large interlocking crystals[1] that are usually bigger than 1 centimeter (0.4 in) and sometimes bigger than 1 meter (3 ft).[2]
![Thumb](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Alkaline_pegmatite.jpg/640px-Alkaline_pegmatite.jpg)
Many of the world's largest crystals are found in pegmatites. These include crystals of quartz, mica, beryl, and tourmaline. Some of these crystals are over 10 m (33 ft) long.[3]
Etymology
The word pegmatite comes from the Homeric Greek word, πήγνυμι (pēgnymi), which means “to bind together." This refers to the interlocked crystals in the rock's texture.[4]