Opal a mineral that is as beautiful and impressive when it is opaque as when it is water clear. The amazing range of this material (considering the simplistic chemistry) makes it an interesting mineral, and that's saying a lot considering the species does not even have any crystal form. The Opal from this Gracious O Dios Mine have been mined for over 150 years, and have proven to be some of the more attractive yet lesser known from the Western Hemisphere. This piece features a few very attractive patches of multicolor Opal on matrix which shows flashes of red, gold, orange, blue and green. Ex. Brian Kosnar Collection.