While Illinois fluorite once was common, it certainly is not so common now on the market and many people search for the even more rare varieties of the color palette once found here in the 1970s-1990s. This specimen, showing a yellow amber colored core with blue exterior phantoms lining, is highly unusual and very beautiful for the contrasts! It is an old specimen from the Ross Lillie collection (of which we bought over 1000 specimens many years ago!). The minute flecks of metallic gitter you see at the edges are small chalcopyrite inclusions, also unusual. The specimen is in good shape overall, although as is common these days, we have sent it to the lab to have small nicks along the edges restored (and they cannot be seen even in UV as the whole specimen glows). The fluorescence is presumably due to petroleum inclusions.