This is a sharp cube of fluorite with gas and liquid phase inclusions. The crystal has an odd almost cloudy or foggy inclusion in its interior. It also has several phantoms of light violet coloration. http://www.mineralatlas.com/specials/phantoms.htm
Fluorite: No more info given at site, really large image linked. Thingofinterest ~I almost suspect tomfoolery with this Unbelievably awesome specimen unlike any I have ever seen, but I post it in the hope it is real and not photoshop.