Emerald (Be3Al2(SiO3)6) is a variety of the mineral beryl, colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5 - 8 on the 10 point Mohs scale of hardness. Most emeralds are highly included, so the brittleness (resistance to breakage) is classified as generally poor. The origin of the word "Emerald" is said to be a Sanskrit word meaning "green".
