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Large Franklin Zincite Crystal Group

Posted by Dana Slaughter  
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Dana Slaughter June 02, 2012 08:03AM
Hello,

I picked up a very large zincite crystal group at the 2012 Minerals of Arizona Symposium in Phoenix. See the following attachment:

http://www.mindat.org/photo-468416.html

The specimen measures 8.5 x 4.7 x 3.5 cm and is virtually pure zincite. I've shown this to friends and we all seem to think that the faces on this piece are actual crystal faces; if so, this is a very large zincite crystal. Is it possible that these could represent a contact with now-dissolved calcite cleavages or could this really be a zincite with over 3 inch crystal faces? I'm no expert on Franklin material and wondered what such a specimen might be worth. Any comments from Franklin aficionados out there would be greatly appreciated.

I don't believe that the flat faces throughout the specimen represent cleavage planes, etc. and one will notice the difference in color between the faces and the contacted or damaged areas on the crystal group (two crystals).



Edited 1 time(s). Last edit at 06/02/2012 08:05AM by Dana Slaughter.
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Rock Currier June 02, 2012 09:04AM
It appears to be a nice pure chunk of zincite without crystal faces.

This is what a good Zincite crystal looks like.

Zincite, Franklin, NJ


Also, check out our Zincite gallery if you have not already done so.

Rock Currier
Crystals not pistols.
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Dana Slaughter June 02, 2012 03:22PM
Hi Rock,

I've admired those somewhat pointed zincite crystals from NJ but I think that other habits are present. The piece that I have does have crystal faces and I'll try to get some better pics. The faces are quite sharp on portions of the specimen and are quite distinct. I'll come back later with a better photo that highlights the sharpest area of presumed crystallization.
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Tim Jokela Jr June 05, 2012 02:37AM
I'm no Franklin expert, but I'm not seeing anything approaching external crystal form there.

Occam's Razor. Look at Rock's photo again.. it's the world's best... quite distinctive.

Mebbe some Franklin experts will chime in.

Given the going rate for genuine zincite crystals, their rarity and small size... that is a truly phenomenal piece if it's a crystal. Surely the world's largest, so you could basically name your price, 5 figures easy.
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Dana Slaughter June 05, 2012 04:08AM
Hi Guys,

I'm no Franklin expert either and I'm basing the possibility of crystal faces on the very smooth and well-defined "faces" on the specimen and the fact these smooth-faced portions have a much duller luster than the areas on the specimen that are contacted. I've sent additional photos off to someone very knowledgeable about Franklin minerals and I'll defer to his judgment. I showed it around at the Minerals of Arizona Symposium and all agreed that the faces appear to be crystal faces but none of those queried is particularly knowledgeable about Franklin material. We're just basing our opinions on personal observation with the specimen in hand.

Perhaps it could be cleavage, parting, etc. but this doesn't adequately explain (to me) the very obvious difference in luster between the dull presumed faces and the relatively bright contacted areas. I think that most of us have used this difference at times to differentiate between cleavage and crystal faces. Thanks for chiming in and I'll check back every now and again to see comments and post new ones where appropriate.
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Dana Slaughter June 06, 2012 04:06AM
Hello,

I've just received a good explanation for this specimen and my hopes that I had a crystal specimen have been dashed! The smooth and somewhat sharp faces are the result of the specimen forming as a fracture filling. 40 years of collecting and dealing and I'm still learning every day.....one of the great things about mineralogy and the hobby! Thanks for the input everyone!
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Jeff Weissman June 06, 2012 02:16PM
Dana - when on a field trip into the Sterling Mine, in 1982, on about the 600 level "central zincite zone" there was a house-trailer, double-wide size, room filled with this stuff, I carried out only a few small samples, unfortunately.
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