Beryllium's name is derived from the Greek name for beryl, 'beryllo'.
Beryllium is found in about 30 different mineral species, the most important being beryl. Well-known varieties of beryl include emerald and aquamarine.
The name aquamarine comes from aqua (Latin for 'water'), and marine, deriving from marina (Latin for 'of the sea'). Because of that, I gave beryllium the symbol for salt water.