Yooperlite

This is a rare thing: a well known mineral find that happened in living memory, on a public beach, by somebody walking with a torch.

In 2017 Erik Rintamaki was working the Lake Superior shoreline in Michigan's Upper Peninsula with an ultraviolet light and started turning up stones that burned bright orange under it. Michigan Technological University analysed them and confirmed what they were: syenite, an igneous rock, carrying fluorescent sodalite. The fluorescent material had also been identified as sodalite by the California collector Gabe Reyna.

The rocks were not new. They had been rolling in that surf for a very long time. What was new was anybody confirming fluorescent sodalite in Michigan at all, and the name, which Rintamaki coined from Yooper, what people from the Upper Peninsula call themselves, and then trademarked.

In daylight a yooperlite is a grey pebble and you will walk past it. The whole thing depends on the light you bring. You need a proper 365 nanometre ultraviolet torch, not one of the cheap 395 nanometre ones sold for spotting pet stains, because the shorter wavelength is what makes the sodalite fire and the longer one mostly floods everything with visible purple.

That means hunting at full dark, on cold wet cobble, next to the largest freshwater lake on earth. Go with somebody, keep a headtorch on white for walking, and watch the water: Superior does not forgive much. The beaches around Grand Marais are where most people start.

Wear UV eye protection. Shortwave and longwave ultraviolet are genuinely bad for eyes over a long session, and this is a hobby people do for hours.