Probably the most common are the many pegmatites throughout the world which have produced gem quality beryl crystals. The pegmatite districts of southern California, Colorado, Brazil, Madagascar, and Pakistan are just a few of the classic areas which produce aquamarine, morganite and heliodor from pegmatites. Beryl may also be found in miarolitic cavities within granite. Examples of such occurrences are Mt. Antero, Colorado which is famous for aquamarine and the Ural Mountains of Siberia. Unlike pegmatites which form after the host rock has solidified, miarolitic cavities form during the same period that the host rock itself solidifies.
Granite is an intrusive, igneous rock.
Beryl has also been discovered in rock formations which are of volcanic origin. These lava flows form an extrusive, igneous environment. The rhyolites of western Utah and a small area of New Mexico are the only known examples. It is these areas which are famous for the bright red beryl crystals which form in lithophysae within the rhyolite. Beryl may also be found in certain metamorphic environments.