What's your opinion on Spodumene/Hiddenite?

Hello all,

I have this specimen of Hiddenite from "Afghanistan" (no further info on locality).

[www.mindat.org]

There seems to be some debate on when people should call it Hiddenite or just plain Spodumene. Quoting the Mindat Hiddenite entry:

"There are disagreements between different people as to what now constitutes a "hiddenite", some claiming it must contain some chromium, others claiming it must be a particular shade of green, others claiming both of the above and that it must be from the Hiddenite area of North Carolina. Colorless or yellow spodumene should not be referred to as Hiddenite."

According to this (http://mcrocks.websitetoolbox.com/post/Hiddenite-2769253), "the Afghan material does not contain Chromium." Mind you, this dates back to 2008, things may be different by now.

I haven't tested my specimen for chromium yet, although it does seem to have a very slight greenish tinge to it, but what do you think I should call it?

Vik

From a mineralogical point of view, it's spodumene.
All "hiddenite" is spodumene.

The International Mineralogical Association only approves definitions of species, not varieties. There are no good, universally accepted definitions of varieties. So you are free to use the name "hiddenite" any way you like. In my personal opinion, I would always use the species name and label it "spodumene". Why bother using varietal names? It is obvious to the viewer that it is green; so no need to write that on the label.

A similar discussion happened years ago with regard to another varietal name: emerald. There were those who wanted to limit "emerald" to those beryls coloured by chromium, in spite of the historical fact that centuries ago the element chromium hadn't been discovered yet, so no one made any distinction between beryls colored by chromium or vanadium or whatever. Similar arguments are circulating recently about whether blue copper-bearing tourmalines from Mozambique can be called "paraiba", like the brazilian ones.

Trying to limit varietal names to specimens from only one locality, even when identical stones are found elsewhere, seems a bit silly. It's like saying you can't call your dog variety a "german shepherd" or "afghan hound" unless it was born in Germany or Afghanistan; if born in America it's just a "big brown dog". Absurd, no?

Alfredo



Edited 1 time(s). Last edit at 03/02/2012 12:22AM by Alfredo Petrov.

My opinion is that if its green Spodumene it's Hiddenite, if its pink its Kunzite and if its yellow it's Triphane

In my catalogue it is simply "spodumene"....on the label in the case it is "spodumene, var. hiddenite". Strictly for the visitors.....

Don

What would you call this one?


How about this?


What about this?


Just spodumene!

Josele

To have a idea about the green color that Spodumene could have please take a look at some Hiddenites that are found in North Carolina: [www.mindat.org]

In my humble opinion we are only talking about a variety of Spodumene if the color is accurate enough to name it Kunzite, Hiddenite or Triphane.
So to me Vic, the specimen you have is Spodumene.

Best regards,
Mario Pauwels

Edit by Rob woodside: This is another interesting post by Dudley Blauwet

About 4-5 years ago, there was an unusual find of about 20 kg of very green gemmy spodumene from the Pech Valley of Kunar Province, Afghanistan. It seems to have occured in a massive seam and the material was highly stressed. It looked more like tremolite, rather than spodumene. I sent some pieces to GIA for an id and they did fade tests in the sunlight for two weeks and the color held, and they determined that there was sufficient chromium that they decided to call it the varietal name of hiddenite.If chromium is present as a chromophore, the coloration is usually more stable, such as in North Caroline hiddenite or the pink topaz from Katlang, Pakistan. There were a handful of pieces which could be called crystals, but mostly they were partings along the cleaveage planes, and nothing much longer than about 3 cm. Almost all of the material was sold to rough dealers, there were very few gems cut from this material as it was so highly stressed that only a handful of expert cutters could cut it without it breaking. It is highly unlikely that you obtained one of these. Many of the spodumene which comes out of Afghanistan and is not exposed to sunlight at the mine is a medium green on the a and b axis and is a blue lilac color on the c-axis. If you expose them to sunlight, they will change to a typical kunzite color rather rapidly. I had a very large one, about 40 cm long about 20 years ago which I put in the sun in June at rather high altitude and it changed as you watched, completing the transition in about 40 minutes, and the color stabilized and remained the same for years. The worst case is if you have an intensely emerald green spodumene. These have been irradiated at a nuclear lab in Pakistan, and are even an emerald green color down the c-axis. They are very unstable and will fade very quickly with the slightest exposure to UV. This intensely green spodumene will fade into a pale yellow gray color. Occasionally there are some found which are a light pastel yellowish-green and they seem to be somewhat more stable. Dudley



Edited 1 time(s). Last edit at 03/04/2012 06:50PM by Rob Woodside.

Relating green colour on spodumene, is not so clear that it is only the Cr which gives the green to the hiddenite. Table No. 1 is an analytical of trace element in spodumene from different origins and colors. Type 5, hiddenite from California, barely containing Cr.
Table No. 2 shows the changes that occur in the valence elements responsible for the color of multiple gems to be irradiated with gamma rays (Co 60). According to this table, clear or pink spodumene turns green due when the valence of Mn increases, Mn is a common trace element in all spodumenes.
From this it follows that some hiddenites are green due to Cr and others may be due to Mn, following irradiation naturally or artificially.

What I know for sure from own experience is that green spodumene coming from Afghanistan (via Peshawar, Pakistan) gradually lose color over time, even saving them in a dark box. And that if you heat a little it lost colour instantly. Not long ago I cleaned with soap and water a green spodumene on matrix for make photograph and as the matrix was somewhat porous and slow to dry, I let it front to the fireplace, about 1 m from the fire. After half an hour you could grab the copy by hand, would be at most 40 or 50 °, was dry, yes, but the green color became light pink.







Bibliography:

Radioactive and Radiation Treated Gemstones
Charles E. Ashbaugh III
Gemological Institute of America

COMPOSITION, TENEBRESCENCE AND LUMINESCENCE OF SPODUMENE MINERALS
Esther W. Claffy
Naval Reseorch Laboratory, Washington DC

RADIATION DETECTION USING THE COLOR CHANGES OF LILAC SPODUMENE
Raquel A. P. Oliveira, Ana Carolina S. Mello, Héstia R. B. R. Lima, Simara Santos Campos and Susana O. Souza
Universidade Federal de Sergipe Departamento de Física Av. Marechal Rondon, s/n 49100-000 São Cristóvão, Brazil

Josele

Here's an apple green spodumene crystal I have. I'm pretty sure it's from Afghanistan:





Would I call it hiddenite? Not really as it isn't the rich deep emerald green of the best North Carolina specimens. The colour has been stable over several years under normal light conditions, and I have had it exposed to sunlight briefly with no ill effects.

Regards,
Nick

Nick, I think your "chartreuse" spodumene is natural colour, not irradiated. Next specimens yes they are irradiated:

Parallel growth crystals sharing (010) face. The color has decreased over time. 10,5 x 3,6 x 2,5 cm.


It was deeper green when I bought it time ago. 8 x 2,5 x 1,8 cm.


Josele

Just to muddy the waters a bit, I ran emission spectra on specimens of "hiddenite" and "kunzite" from Brazil using a 405nm diode laser. The "hiddenite" showed broad peaks at 530 nm, and in the NIR at 740 nm. There was a sharp Cr peak at 690 nm superimposed on the 740 peak with a suggestion that other Cr peaks were not resolved from the broad peak overlap. The "kunzite showed only a single broad peak at 600nm. Not certain how to interpret this in spodumene, but there is little doubt that at least some of the "hiddenite" of lighter green color does contain Cr.

Henry Barwood
Troy University
Troy, Alabama USA

Here is a strangely coloured one I have from the same general area. I also have a few of the ones Rob speaks of and will attach some photo's soon.

What should we call this one

Perhaps KRYPTONITE irradiated? So dark sidecar Q use to be irradiated.
Craig, very nice piece, in the picture it looks as hexagonal prism, a rare spodumene!

Josele