? about Hiddenite

[daniil]

Hello all, I am brand new to this forum. I have been collecting colored stones for few months now and found this forum very helpfull. I was wondering if hiddenite color fades when exposed to light as another member of the spodumene family, kunzite does? Thanks in advance for your help.

 

[Richard M.]

Interesting question. According to Schumann yes, its colors can gradually fade. It''s pretty rare stuff although I read about a discovery of some nice crystals in North Carolina about a year ago.

Richard M.

 

[MJO]

I accidently left a stone out in the sunlight for a coulpe of days and it is now a clear colorless stone. If you ony wear it at night and put it in a dark area it will be ok. There has been a large find of wonderfully large clean crystals in Afganistan.

Regards,
Maurice

 

[rainbowtrout]

richard: sorry for my ignorance, but what exactly *is* hiddenite?

 

[Richard M.]

Date: 12/11/2005 10:14:17 PM
Author: rainbowtrout
richard: sorry for my ignorance, but what exactly *is* hiddenite?

It''s the green variety of the mineral spodumene. The pink to purple variety is kunzite. It was named after W.E. Hidden who discovered it in 1879 in North Carolina. For many years that was the only known location but deposits have now been found in Brazil, Burma, Madagascar and Afghanistan.

 

[daniil]

Thanks a lot for you help Richard and Maurice. I have another question for you. Once the color is gone is there any way to get it back, like heat or radiation?

Thanks, daniil

 

[MJO]

Date: 12/11/2005 10:43:19 PM
Author: daniil
Thanks a lot for you help Richard and Maurice. I have another question for you. Once the color is gone is there any way to get it back, like heat or radiation?

Thanks, daniil

I''m not sure but I have heard it can be irradiated back to it''s original color. There is also a rare blue spodumene called blue Hiddenite from Afghanistan.

Regards,
Maurice

 

[rainbowtrout]

I read a bit about this stone on the web, and it apparently is a chain silicate, so it and opal are made out of the same base mat''l...this does not explain to me why the color fades so easily, however..nothing seems to note why this happens, just that it does.

Would the silica mat''l have anything to do with its pleochroism?

 

[Richard M.]

Pleochroism is a function of a mineral''s crystal structure. Diamond, garnet and spinel, are singly refractive because they''re all isometric/cubic. So are amorphous gems like opal with no crystal form. All other crystals are doubly refractive with either one or two directions of single refraction.

Doubly refractive stones split light rays in two directions and show two different colors due to differing absorption of light. Some crystals like zoisite (tanzanite) are trichroic and show three different pleochroic colors. Spodumene crystallizes in the monoclinic system so it''s doubly refractive with two directions of single refraction. There''s no pleochroism in singly refractive directions.

Color change due to exposure to sunlight, heat or radiation (light and heat are radiation too!) is caused by the arrangement of atoms in what are known as ''color centers.'' It''s complicated subject and several excellent books have been written about it. I believe fading in gems like topaz and spodumene is due to removal of color centers by heat or light. Here''s a tutorial about the causes of color in gems.

Richard M.