Emerald (BeAl(SiO)) is a variety of the mineral beryl, 236 colored green by trace amounts of chromium and sometimes iron.

Beryl has a hardness of 7.5 on the 10 point Mohs scale of hardness. Emeralds in antiquity were mined by the Egyptians and in Austria as well as Swat in northern Pakistan.

A rare type of emerald known as a trapiche emerald is occasionally found in the mines of Colombia.