Add Yahoo as a preferred source to see more of our stories on Google. Most people do their rock hunting during the day, but you can't find "Yooperlites" until the sun goes down. Yooperlites are rocks ...

Yooperlites are rocks that fluoresce under UV light. The best time to search for Yooperlites is after a storm, when waves may have unearthed new rocks along the shores of Lake Superior. Rock hunters ...