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"Yooperlite" - What's in a Silly Name? What are they really?

A rock just went viral! A fellow found some glowing rocks on the beaches of Lake Superior and quickly realized how neat they were. He did some investigating, wandered over to the Facebook Fluorescent Mineral Group, had some ID work done, and confirmed that they were actually a mix of several minerals - sodalite, an alkali feldspar, and a bunch others - usually referred to as (nepheline?) syenite (an igneous rock containing several minerals). Sodalite is the mineral that is fluorescing orange and is very often one of the minerals in syenites from alkaline complexes . In Greenland's Ilimaussaq Complex the combination is a basic rock-building assemblage- usually referred to as naujaite.

These "Yooperlite" rocks have been worn smooth by wave action over eons, and it is generally accepted that glacial activity transported them to the shores along the Great Lakes from the Caldwell Alkaline Complex in Canada. They seem to be also found in Wisconsin, and maybe even Illinois. For more musings on these glowing rocks visit

(From a paper written by ROGER H. MITCHELL AND R. GARTH PLATT, Department of Geology, Lakehead University, Thunder Bay, Ontario, Canada these rocks from the Caldwell Complex are nepheline syenite with minor and accessory pyroxene, biotite, natrolite, titanomagnetite, apatite, zeolite, fluorite, zircon, sphene and sodalite.)


Yooperlite fluorescing under 365nm longwave UV. Photo courtesy Erik Rintamaki, FB Group

He nicknamed them "Yooperlites" and they quickly gained fame. There was a write-up in the Mineral News, the "discovery" was picked up by local news stations and then by CBS News, online posts went viral, and the rest is history. People started listing them on Ebay and they instantly were bid up over $100 for a little river pebble. It's the first rock fad I've seen since pet rocks! Personally I hope it grows and Walmart starts carrying them - what better way to spread the word about fluorescent minerals!?!?!

Many people discourage the use of nicknames, or inventing new names, for a rock. It causes confusion and is not terribly professional. I don't disagree but understand the reasoning behind this. There is a certain amount of regional pride in the Upper Peninsula in the name - and he does get bragging rights, having done the work to ID the minerals and get the data published.

But - it is a nickname for a rock with relatively common minerals (sodalite being the fluorescent mineral) that have been water-polished over centuries or more. There's a lot of misinformation floating around on the IDs. Many are calling it syenite. While true the "rock" is referred to as syenite, it's the "mineral" sodalite that is fluorescent. The orange "glow" is a common response of sodalite under LW UV and similar can be found in Canada, Greenland, Norway, Afghanistan, and several other places around the world. If any of the localities in those places have a river running through it you will likely find this tumbled variety. I guess you could give it your own name, or call it a "Yooperlite Type" sodalite, or just call it what it really is - sodalite.

Not to be left out, Greenland has its own “Yooperlite style rock” (but we just call them sodalite). Glaciers eroded sodalite out of the Ilimaussaq Complex and carried them towards the ocean, grinding and polishing all the way. Many were deposited in the glacial moraines near the village of Narsaq. Lots more can be found on the pebble beaches in the fjords cutting through the complex. The sodalite is brightly fluorescent under LW (365nm). The pic below shows 6 rocks, three of which are the result of splitting one larger rock to reveal the interior. When split, many (such as this one) exhibit a strong tenebrescence after exposure to shortwave (SW) UV (see animation below). This is (so far) a Greenland exclusive. Minerals include sodalite, arfvedsonite, aegirine, eudialyte, and probably a few others, all in a syenite type rock.

Greenland Style Yooperlite

Sodalite from Greenland that has been worn and tumbled by water and glacial activity

Pieces from Greenland look identical to the Yooperlites from Michigan with only a couple of exceptions: they are quite large usually, and they are often tenebrescent inside. The pics above shows the big rock split in two, before and after exposure to SW UV. Animation below shows it a little better.

Tenebrescent Sodalite

A quick note on photography: Lots of new people (new to fluorescent minerals) are taking pics of these and selling online. The pictures are terrible. They are using unfiltered, 395nm UV lights and taking pics on fluorescent backgrounds. Some complain that it requires expensive lights to take good pics - but the $25 Convoy S2 works just fine. Here's a sampling of photos from Ebay: (in this comparison I'm just worried about the terrible purple haze. Sodalite, when overexposed, will appear yellow as seen in the last pic. It should be orange but I won't worry about that right now since most photos barely show any resemblance to acutal fluorescence.)

The following is an opinion piece I posted a few days ago in the FB FLM Group. Views expressed here are my own:

For the past few days “Yooperlites” have dominated the conversation in our group. Some folks have been having a lot of fun, while others seem distressed by the somewhat trivial discussions. I, for one, am amazed that any FMS member would consider this topic frivolous. It is the most important development in our hobby since the Convoy. From the FMS website: “The mission of the Fluorescent Mineral Society is to bring together people who are interested in fluorescent minerals, and to introduce the public to the hobby of fluorescent mineral collecting. This mission is pursued by promoting fellowship and educational activities, and supporting research that increases basic knowledge of fluorescence and fluorescent minerals.” Yooperlites have introduced far more people to our hobby than any other happening in recent history. Along with the Convoy UV flashlight, more folks can enjoy our hobby than ever before. So far this week we have seen over 50 new members join our Facebook group – a record. Howie coincidentally decided to run a promotion for new FMS members and, by my count, has had at least 7 new members join the FMS; probably would have been more if the FMS signup page weren’t so screwed up (and he must now embark on another collecting trip to fulfill his rock offer). Last week there were no Yooperlites offered on EBay. Today there are over 50, with many bid up to $100 or more. These are being sold by newbies to Ebay and are listed in random categories instead of the FLM category, further spreading the FLM word to non-fluorescent collectors. (Don’t worry, this Ebay fad will die quickly. I posted a quasi-yooper auction just so I could advertise the FMS and our FB group.) Yooperlites have gone viral. There are at least 452 official news stories returned by Google compared to none a year ago. CBS News, MSN, dozens of local news stations, several write-ups in newsletters, 16 videos on Youtube (one was even posted on WeChat in China), they’re even posted on Instagram already. On Reddit (“the front page of the Internet”) Yooperlites reached the front page (a major win) as one of the most popular topics and there are no less than 40 different posts made about them. Traffic to Nature’s Rainbows has experienced a major uptick, with folks going on to explore mineral lights, the Convoy article, and more (see the entry page table below for the past week). Referrals to Nature’s Rainbows have hit an all-time record high (see graph) of people searching for fluorescent mineral topics. Collecting FLM, the Convoy, FLM lights, are among the top blog posts on Nature’s Rainbows for the past week (see graphic). Visits per/day have doubled. New members in our FB group have skyrocketed (last graph). Yes, “Yooperlite” is a silly made-up name. But it is derived from a proud regional moniker and is fun to say. Hundreds, maybe thousands, of kids (and adults) are/will be searching for them on the shores of the Great Lakes. Their parents will have to buy a Convoy and teach them about fluorescent minerals. That will result in an influx of new hobbyists not seen since the Convoy hit the stage three years ago (and will easily become the most important source of new members for our hobby - all-time. This mania does exactly what the FMS wants – spreads the word about our hobby. So – I say lighten up. Embrace it, don’t fight it. Have some fun, help new people learn, contribute to their understanding of FLM. Make scientific posts, expand on collecting, guide new folks as they learn about our hobby. At the very least, stop complaining about all the Yooperlite posts. This will grow our hobby.

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