‘Yooperlite’ is actually a trademarked brand of what is officially known as a “syenite rock rich with fluorescent sodalite”. But if you’re unsure of what exactly it is we’re talking about here, a ‘Yooperlite’, in short, is a special kind of fluorescent rock that you can find predominantly along the shores of Lake Superior that, as the trademarked name suggests, can glow when subjected to specific lighting conditions.
