White opal, precious opal with white or very light body color.
Natural opals with a base tone ranging from colourless to medium grey are called light opal. Some people refer to these as "white," although this expression should only be used where the body colour is very milky.

Light opal makes up the bulk of precious opal. White Opal may be transparent through to nearly opaque, although it usually has a "milky" appearance and has a light body tone or white body colour.

Mainly mined at Coober Pedy and Mintabee, (South Australia) although the first deposits were found at White Cliffs (NSW).
Light opal is also classified as a solid opal. Coober Pedy, Andamooka and Mintabie in South Australia are the most productive mines for light opal.      
A full range of colours swirls and flashes in the depths of a light opal. The background colour may be white or light blue. Light crystal opal is translucent and shows colours sharp and visible below the surface. When clear and colourless, this form is referred to as 'water' or 'jelly' opal.
More recently, Mintabie has discovered the more vibrant semi-black opal, which is tremendously popular for its beauty, and not as expensive as black opal. Light opal has a lighter background while semi-black opal has grey colour tones.