That white "crystal" atop this large plate of amethyst from Morocco is not what it appears to be. What you are looking at is an eggshell-thin cast of quartz that formed around a calcite crystal, retaining its form perfectly after the calcite inside was etched away by corrosive solutions in the pocket. There is a little peephole that lets you look inside. What a stunning pseudomorph, and perched right up there on a perfect setting! A very unusual specimen, not something that came out in quantity from this locality.