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Improving Mindat.orgBower Powers Black Tourmaline

14th Oct 2015 21:27 UTCJohn Betts

The locality description for the Bower Power's site (http://www.mindat.org/loc-7930.html) in correctly states:


"The black tourmaline from this locality was historically called schorl and then iron-rich uvite. However, when the published rules of the recent IMA tourmaline nomenclature committee are followed, the correct species is dravite. See Chamberlain & Robinson (2013) Collector's Guide to the Minerals of New York State, Schiffer Books."


Steve Chamberlain unilaterally decided to lump ALL black tourmaline specimens as dravite, when in fact uvite was detected. Following is an email from Steve:


"In our coming book (due out in January, 2013) George Robinson and I have adopted Marian's unpublished analyses and nomenclature of tourmalines from New York State. Marian was the technical reviewer for our book and provided all his tourmaline data. We list the black tourmaline from Bower Powers as dravite. If you analyze enough specimens from this locality you can go crazy since a few xls are compositionally zoned. However, comparing samples from five different sites across the occurrence, we are pretty certain they are all the same thing. Since the preponderance of Marian's analyses are dravite, we went with that. It is better to pick a name and use it than confuse everyone with all the hedging, ifs ands and buts."


But there should be both Dravite and Uvite listed for the locality.


Marian Lupulescu of the New York State Museum wrote:


"I did analyzed many crystals from that location and the results are uvite or dravite! I would not say that all the crystals are uvite or dravite. I cut one crystal along the ‘c’ axes and probed it. When I calculated the empirical formula the interior appeared to be uvite and the rim…dravite! But, I do not think this is true for all the specimens that were collected from Bower Powers Farm. Taking into consideration the range of compositions close to the uvite-dravite bounday, I advise people to call it uvite-dravite or “black tourmaline from BP’ unless the chemical composition of the specimen is known.

14th Oct 2015 21:29 UTCJohn Betts

Additionally the strikethrough text style for "Uvite" should be removed from the species list to make uvite a valid species for the locality.

14th Oct 2015 21:48 UTCAlfredo Petrov Manager

Thanks. John.

Fixed.

14th Oct 2015 23:27 UTCRob Woodside Manager

So we said a RRUFF photo http://www.mindat.org/photo-309566.html posted in 2010 was wrong until now! Thanks for finding this!

15th Oct 2015 17:07 UTCRichard Gunter Expert

Are these F or OH dominant Dravite-Uvite?

15th Oct 2015 17:33 UTCGerhard Niklasch Expert

The particular sample studied by RRUFF mentioned by Rob is F-dominant at the on-axis site (55 atom %, see the caption of that photo), but these tourmalines are near the midpoint in this regard, too - so they may lie on either side, and this may even vary from one zone to another.


Enjoy,

Gerhard

15th Oct 2015 18:19 UTCRichard Gunter Expert

So what do we call them? Fluoruvite-Fluordravite-Hydroxyuvite-Hydroxydravite sounds a bit too cumbersome.

15th Oct 2015 18:23 UTCRob Woodside Manager

Unless the piece is analysed, it is all tourmaline!

15th Oct 2015 18:53 UTCRichard Gunter Expert

Hi Rob;


Tourmaline does not fit on the locality page. Even if the samples are analyzed all four phases might be present so in this case it is tourmaline whether analyzed or not.

15th Oct 2015 19:03 UTCReiner Mielke Expert

I'm changing all my labels to tourmaline! I've had enough of this.

15th Oct 2015 19:26 UTCRichard Gunter Expert

I have as well. It seems the simplest solution.

15th Oct 2015 19:46 UTCAlfredo Petrov Manager

I've always said that "tourmaline" is a beautiful name, and there is no shame in writing it on a label! Let the systematik fanatics keep on trying to guess what they really have :-D
 
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