Yooperlite

Yooperlite is the popular trade name for a fluorescent sodalite-bearing syenite rock found especially along the shores of Lake Superior in Michigan’s Upper Peninsula. In normal daylight, Yooperlite can look like an ordinary grey, speckled or pale igneous rock. Under ultraviolet light, however, patches and veins containing fluorescent sodalite can glow vivid orange or yellow-orange. The name Yooperlite was popularised after rock hunter Erik Rintamaki discovered the fluorescent stones along the Lake Superior shoreline in 2017. The word combines “Yooper”, a nickname for people from Michigan’s Upper Peninsula, with “-lite”, giving the stone its distinctive commercial name. Yooperlite is not a separate mineral species. It is a multi-mineral syenitic rock containing fluorescent sodalite alongside feldspar and other minerals. The Lake Superior examples are believed to have originated farther north, most likely from the Coldwell Alkaline Complex in Ontario, Canada. Glacial activity transported pieces of the rock southward and deposited them around the Lake Superior region, where waves later rounded and polished many of the stones. The dramatic contrast between its plain daylight appearance and intense ultraviolet fluorescence has made Yooperlite especially popular with mineral collectors and UV rock hunters.