This is a silicate with high moisture content. It doesn’t have a precise structure but does contain layers of tiny silica spheres, which affect the light passing through and thus give the astonishing rainbow of colours for which Opal is famous. Opal is wonderful for bringing out original creativity and emotional imagination. It’s a fun stone which encourages you to get out of your comfort zone, so can also be a bit unbalancing - hence it teaches centring! There’s a lot of potential with this stone to enhance psychic development and bring out your true and original self.
Potch Opal is exactly the same mineraloid but the silica spheres have no particular structure and hence there is no light play.