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Identity HelpFranklin NJ Mineral Identification

14th Jan 2018 16:57 UTCDoug Gardner

This specimen comes from the Buckwheat Dump in Franklin NJ and is fluorescent in light blue in UV-SW. I’m trying to figure out what the green crystals are which I think is the fluorescing mineral. The small crystals are transparent and vitreous and cover the specimen as can be seen in the 20x magnified version and range from green to deep green to brown/black. The matrix is probably Calcite. From a distance the piece looks like Microcline but I don’t think it is. My guesses for the green crystals are Pargasite or Diopside.

14th Jan 2018 17:19 UTCHarold Moritz 🌟 Expert

Did you put any acid on the white matrix? What is its hardness? What fluoresces light blue? The matrix? Grains in the matrix? Need more information.

The pix looks like marble matrix. If there is no orange-red fluorescence, then it's not calcite from the orebody, just a hunk of Franklin marble.

But microcline from there can fluoresce light blue. Would be the whole mass if that is the matrix. If the fluorscence is just some colorless grains, then they are likely diopside (it does not have to be in the orebody to fluoresce).

The green grains could be an amphibole or a pyroxene, cant tell by the color, so many have been redefined as species or the IDs have changes since the reports were written - could be diopside, hedenbergite, augite, pargasite, edenite, actinolite, a hornblende species, etc. But I think light blue fluorescence is limited to diopside, but if the diopside grains are green then the Fe content will quench the fluorescence.

If the green grains are not fluorescing, then they are likely an amphibole as it would be unusual to have two pyroxene species together, more likely to have a pyroxene and an amphibole together.

14th Jan 2018 17:42 UTCDoug Gardner

Thanks for the response. Your questions made me look closer. It is the matrix that is fluorescing blue-green not the green crystals. There is no orange-red fluorescence anywhere so the matrix is not Calcite. The matrix does not scratch glass. The green crystals are too small for any physical analysis. I thought diopside from Franklin was more of a gray color.

14th Jan 2018 18:56 UTCMark Heintzelman 🌟 Expert

Looks to me like a mix of marble and pyroxene, a fine grained Coccolite (a rock).

Here are two samples with larger grains, one from Sulfur Hill Mine, NJ diopside and calcite (marble), the other is from Till Foster Mine, NY diopside chondrodite and calcite (marble).

I wouldn't expect any fluorescent response from marble. As Harold points out, iron quenches UV. I know the fluoresent diopside I have from Frankiln marble, associated with fluorite, is very pale and translucent and you might not distinguish it from the surrounding marble without a closer look.

diopside & marble, Andover, NJ - 6.3x5x5cm diopside, chodrodite & calcite, Brewster, NY 7x5.5x5cm

14th Jan 2018 19:10 UTCChester S. Lemanski, Jr.

The matrix may be microcline. Microcline from Franklin fluoresces an unusual gray to blue-gray, and even bluish under SW.

14th Jan 2018 19:24 UTCDoug Gardner

Thank you Mark. The green crystal Diopside grains in your sample on the left from Andover looks similar to mine. I believe I'm not seeing fluorescence from the Diopside if that is what it is.

14th Jan 2018 19:26 UTCGary Moldovany

Second vote for microcline. I have even had a specimen of microcline be mistaken for a margarosanite, it was that bluish-white fluorescence. The matrix is typical Franklin. What you have is a common specimen with no special value. There are many specimens of this on the Buckwheat Dump.

15th Jan 2018 07:29 UTCA. M.

Third vote for microcline, with green minute gahnite and mica.

https://www.mindat.org/photo-652541.html

15th Jan 2018 12:07 UTCDoug Gardner

Thank you. Identifying Franklin minerals requires more experience than I have. With these suggestions under 40x the small green crystals look Spinel shaped. Gahnite on Microcline is starting to feel right.

15th Jan 2018 13:23 UTCHarold Moritz 🌟 Expert

Just because there is no orange-red fluorescence does not rule out calcite because only the calcite from within and immediately near the ore veins fluoresces. Use lemon juice or vinegar to test for calcite if you dont have any other acid. But the overall pic looks like microcline to me, I have a similar chunk. Green grains could be many things, including gahnite (if this piece is from the ore vein), but I think they are pyroxene or amphibole.

22nd Jan 2018 01:07 UTCDoug Gardner

Harold,

Under magnification the green mineral doesn't look like an amphibole at least not to me with limited experience.

There was no reaction on the matrix with 5% Vinegar.

Doug

22nd Jan 2018 01:43 UTCKevin Conroy Manager

You may want to contact Peter Giangrande, who owns The Enchanted Rock Garden. Although his shop is in Minnesota he grew up around Franklin, and he's one of the leading experts on the minerals of that area. Here's his info: http://www.enchantedrockgarden.com/contact/

22nd Jan 2018 02:13 UTCKevin Conroy Manager

I forgot to mention that there are two outstanding museums in the Franklin area that you can also try.

Franklin Mineral Museum: https://franklinmineralmuseum.com/contact/

The Sterling Hill Mining Museum • 30 Plant Street, Ogdensburg, NJ 07439 • Tel: 973-209-7212 • info@sterlinghillminingmuseum.org

At this museum you may want to try contacting Robert Hauck: http://sterlinghillminingmuseum.org/aboutus/bios/rhauck.php

22nd Jan 2018 16:45 UTCDonald B Peck Expert

Chet Lemanski and Gary Moldovany are also from the Franklin/Ogdensburg area and i would definitely call them experts . Chet worked in the Sterling Hill Mine, and I would bet that Gary did too.

22nd Jan 2018 18:10 UTCMark Heintzelman 🌟 Expert

Agreed . . it takes "boots on the ground" to really know the local gangue material.

I both trust and defer to Chet's assessment and Gary's confirmation of it.

22nd Jan 2018 18:56 UTCKevin Conroy Manager

I also agree that Chet and Gary are top experts. It just seemed that Doug was looking for further confirmation so I was providing alternatives.

23rd Jan 2018 12:18 UTCGary Moldovany

Thanks for the recommendation, Don, but I never worked in the mine (except in my dreams!). I have been collecting Franklin/Sterling Hill minerals for about 15 years but I am not an expert, just an enthusiast with a pretty nice collection. There are far more knowledgeable folks than me in this community!

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