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UV Mineralsphosphorescent petoskey stones?

25th Sep 2018 08:34 UTCDon Windeler

Folks:

While I've been collecting a long time, I've never had a good UV light with which to play around. I've borrowed a SWUV light from a friend and am now getting myself into all kinds of trouble, some of which will get photographed when I can drag my wife into the fray.

She's got a bunch of random polished agates and other rocks she keeps in a bowl and we were running them under the light tonight. Much to my surprise, a Michigan petoskey stone showed up as somewhat yellow and then phosphoresced weakly for about five seconds after I turned the light off. (Petoskey stones are the state rock of Michigan, basically fossilized hexagonal corals that show cool patterns.)

I guess I'm not that surprised about the fluorescence because I've read about fossils doing so (and many are calcite) but hadn't ever heard about phosphorescent petoskey stones. (No, I'm not trying to kick off the next yooperlite craze!) I'm honestly pretty ignorant about fluorescent rocks -- is this something others have run across with petoskey stones? Sorry no photos -- we haven't tried playing with UV photography yet.

Cheers,

D.

25th Sep 2018 14:13 UTCPaul Brandes 🌟 Manager

Thank goodness. Don. I don't believe Michigan could handle another mineral craze..... ;-)

I too have some petoskeys that are fluorescent and stay lit for a few seconds after the light is removed. What I find interesting is that not all petoskeys show this habit; I have about an equal amount of each. I have searched around Rockport on Lake Huron and also observed this phenomenon. I don't know exactly why some fluoresce and others don't. I just assume it has to do with the amount of activators in the fossil/calcite that react to a uv light.

30th Sep 2018 18:24 UTCDon Windeler

Thanks for the comments, Paul. I really don't have a lot of knowledge on fluorescents, but can totally understand how people get into it. Just running the light over my collection pops up all sorts of unexpected surprises. I have an ugly little calcite on breccia I collected from the Barney's Canyon Mine in Utah almost 30 years ago that I only kept as a memento. Turns out under SWUV the breccia fill material screams orange-red like Franklin! Now I have to figure out how to get a couple of these rocks photographed...

Cheers,

D.

3rd Oct 2018 23:11 UTCBecky Elizabeth

Hey All,

I hope I'm not being rude asking a question on someone else's thread but I was about to post a question about fluorescent sodalite v. hackmanite v richterite etc when I saw this question.

I started collecting stones and crystals in the "metaphysical realm" for gifting to others and as an alternate form of healing etc. However after studying and becoming a member here I've learned about so many literal Hacks that are cheating people out of money by using trademarked names etc and I'm trying to educate that community about some of it.

On to why I'm here- I've been debating on ordering Petoskey stones for a while but can never get a straight answer about them. On various websites they look like "lionskin quartz" on others they look like "lodolite"/garden quartz.. I know these are also trade names for quartz with inclusions but these "common stones from Michigan" sell for upwards of $4/ each online and if they're that common I cant justify it and was hoping for a little insight. Are we talking about the same stones?

Thanks so much!

Becky Elizabeth

Wilmington, NC

3rd Oct 2018 23:50 UTCRoger Ericksen 🌟

Petoskey stones are fossilized coral composed mainly of the mineral Calcite.

Mindat photos and info

3rd Oct 2018 23:55 UTCBob Harman

BECKY, The accompanying photo is of my examples of self-collected natural and polished petoskey stones. Genuine Michigan examples of polished petosky stones should sell for more than your mentioned price. There are polished look-a-likes from other places, such as China, that use similar, but non Michigan species of colony corals. Best way I have found to tell a genuine Michigan example is to have an invertebrate fossil expert examine the example. Is the coral from Michigan or is it a similar species found in another part of the world? CHEERS....BOB

4th Oct 2018 01:11 UTCBecky Elizabeth

Cheers Bob!

These definitely look extremely different from the stones I saw so I will look and take a screenshot of what they are selling. These stones do not remotely resemble fossils, coral or fossilized coral! I remember reading they were very "rare" and I threw $4 out there because that was the lowest price I'd seen for "chip" sized stones.

I'm about to post under a sodalite question with my 1st attempt at taking a photograph with a small shortwave uv/backlight flashlight from Amazon. I know it's not too of the line equipment but for $7.99 and free 2 day shipping it's been a fun gadget- I don't work for them or anything but I read that you and your wife were looking at them so I figured I'd share my new toy as well.

Thanks again for the responses and I'll be back!

Becks!!

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