I've been finding a number of localities for fluorescent drusy quartz crystals in western Wisconsin. They show a yellow to orange fluorescence under medium and short wave UV. There are occasionally green fluorescing areas. The fluorescence does not appear to be from inclusions, coatings or matrix - it seems to be from the quartz crystals themselves. The environment seems simple geochemically - vugs in Ordovician dolostones of the mid-continent with only associated dolomite, calcite and goethite pseudomorphs after marcasite and pyrite. Any thoughts on what the activators may be? My sense is that luminescent quartz (not chalcedony) isn't too typical. Thanks!