Pegmatite

Pegmatite is a very course-grained igneous rock with which emerald is found. Pegmatite consists of a combination of quartz, feldspar, and mica.

Pegmatite is widely distributed across the earth, and is most abundant along mountain chains.

Pegmatite material tends to be very old, with most deposits ranging from 1 to 2 billion years old, with some of the oldest having been formed as long as 3 billion years ago.

However, much younger deposits such as those around India date between 5 and 20 million years old, having formed in the current Cenozoic era.

Economically, pegmatite is a very important material because they so often contain rare gemstones and is the source for many other significant elements such as tin, tungsten, and lithium.