““surprisingly dramatic glow some minerals gave off when illuminated with ultraviolet light, or “black light.” In daylight, for instance, the mineral fluorite is a drab, chalky color; in a dark room under UV light, though, fluorite glows a brilliant blue; the mineral calcite shines bright red; and aragonite gives off a neon green. If you’ve ever stepped into a teenager’s cavelike room decorated with black-light posters (less common now than they were in the 1970s, when my three sons were growing up), you’ve seen another version of UV fluorescence in action.””
