When these pseudos were first discovered at the Ray Mine in 1976, they were x-rayed, which determined that the blue-green outer rim was chrysocolla after either gypsum or azurite. But a question was raised that the original crystallization appeared to be that of an unknown orthorhombic mineral, which would exclude both azurite and gypsum, both of which are monoclinic. The color has deepened over time with a natural patina, in this specimen, for when it first came out it was a sky blue. On the back side, there is an unterminated crystal but it does not materially affect either the appearance or value. Most people seem to be labeling these as after azurite now, in this habit, although some others DO look more like selenite and get that appellation. Anyways, a fine one of competition quality!