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Identity HelpSterling hill fluorescent

16th Nov 2019 14:45 UTCBrian Fussell

Looking for an idea of what these granular dull yellow/green fluorescing  minerals could be, they fluoresce under long wave only. The rock is grey calcite with franklinite from Sterling hill, I thought willemite initially before turning on the uv lights. Photo above is longwave 365nm

16th Nov 2019 14:46 UTCBrian Fussell

short wave.

16th Nov 2019 14:46 UTCBrian Fussell


17th Nov 2019 14:35 UTCA. Mathauser

Humite/chondrodite or tephroite - ? But tephroite is not fluorescent.

19th Nov 2019 13:43 UTCBrian Fussell

Thx A.Mathauser. Chondrodite looks like a good candidate for sure. Didn't there used to be a fluorescent section to this forum?

19th Nov 2019 13:58 UTCChester S. Lemanski, Jr. Manager

Chondrodite/norbergite do not occur within the ore zone where this specimen comes from. Neither fluoresce under LW UV, only SW. This one puzzles me too!

Check the Franklin Mineral Museum website - there should be a list of all the fluorescent minerals that occur in the area.

Chet Lemanski

19th Nov 2019 19:40 UTCJeff Weissman Expert

Under the long-wave, is this really a pure fluorescent response, or is some visible light getting through, the calcite under LW should be much brighter red, looks like some visible light is washing out the response as imaged. If all I saw was the visible light image, I would have said andradite.

20th Nov 2019 13:27 UTCBrian Fussell

Are you referring to color or actual brightness Jeff? I did intentionally under expose the image a touch so the main minerals I was shooting did not get over exposed. I also am using a bandpass filter on the UV light which can make the color appear different than with out.

20th Nov 2019 22:40 UTCJeff Weissman Expert

Brian - the LW image looks as if there was some visible light leak contributing to the image, wanted to confirm. Otherwise, I am at a loss as to what this is. Some willemite is known to fluoresce yellow. Barite is another possibility. Are we looking at a fresh break or a weathered surface? If weathered, could be secondary calcite or aragonite.

21st Nov 2019 03:49 UTCBrian Fussell

Its not a freshly broken surface Jeff, so maybe it could be one of those.

Just for fun I stopped by a local rock shop that happened to have some Norbergrite, bought and took some images to compare since it was listed as a possible suspect.

21st Nov 2019 03:50 UTCBrian Fussell

long wave. Norbergrite

21st Nov 2019 03:50 UTCBrian Fussell

Short wave.

21st Nov 2019 14:12 UTCMatt Courville

Hi Brian,

perhaps you have some Sphalerite (var Cleiophane) found in this region?

21st Nov 2019 22:47 UTCA. Mathauser

Where was the specimen found? If from dump pile at Sterling Hill (next to museum), it is possible it's Franklin. Rocks have the feet - human feet ;-)

22nd Nov 2019 14:24 UTCBrian Fussell

Purchased this and 4-5 others from a  local shop in WI, so cant say what pile they may have come from.

22nd Nov 2019 15:16 UTCKevin Conroy Expert

Depending on where you are in Wisconsin, you may want to stop by a rock shop in the Minneapolis area.   Despite the "Enchanted Rock Garden" name, the owner (Pete Giangrande) is VERY knowledgeable on Franklin minerals.   I know that we have top experts here at Mindat on Franklin, but sometimes being able to see a specimen in person instead of on photos really makes a difference.   Anway, if you want to make the trek: 

22nd Nov 2019 12:36 UTCMatt Courville

Chondrodite/norbergite do not occur within the ore zone where this specimen comes from. Neither fluoresce under LW UV, only SW. This one puzzles me too!

Chester has pointed this out - the latest photo above does look quite close to yours...

For such a well known area to collect I would assume someone has analyzed for the chondrodite by now, but perhaps what was always assumed to be chondrodite, was in fact not?? 

If the rocks were dumped, then it's unfortunately always a mess to sort-out, but peple generally don't dump their 'leaverites' far from parking areas because of laziness;)  If it came from deep in a pile or far-in a quarry I would generally assume it's local.
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