Green-Red White Crystal Opal from Coober Pedy, Freeform

About White Crystal Opal

White crystal opal has a white to pale body colour and is translucent to partly transparent, rather than opaque like common white opal. It may show flashes or broad patches of play-of-colour, produced when light is diffracted by regularly arranged microscopic silica spheres. Opal is a hydrated, non-crystalline form of silica, often described mineralogically as a mineraloid. Hardness is approximately 5–6.5 on the Mohs scale.…