A very FINE specimen of bright, micro-dendritic copper in a TERMINATED transparent gypsum cleavage from the Mission Mine of Arizona. OLD and very choice material, which comes with a 1960s-70s-era Styrofoam base with a pinned label. Such windowpane slices are almost never available, ESPECIALLY a terminated one! In person, looking at the internal meshwork, you can see how mesmerizing this is and why it is such a classic. Ex. George Elling Collection. very neat piece!