A very rare example of this fantastically beautiful mineral, one of the few species that forms purest yellow crystals (and isn't sulfur!). The crystals here reach over 1 cm and are clustered nicely in the middle of the specimen. It is, really, display-quality AND significant. It has been since around 1999 when I last had a good example of this species to offer for sale; and I have not seen any elsewhere in the meantime, either. An American classic, it should be - but its so rare, that few know of it these days! This comes out of a small midwestern museum collection