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 Post subject: A Determinitive Use for the Chelsea Filter
PostPosted: Sat May 12, 2012 8:28 am 
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:shock: I really never expected to be made aware of a determinative use for a Chelsea, but I've discovered one.
Courtesy of Dr. Ulrich Henn (current head of DGemG) at the SGA conference.

re: Prasiolite
As you are aware most prasiolite is artificially produced by heating amethyst from certain locations, like Montezuma, Brazil. Certain heated amethyst goes green as opposed to golden (citrine).

It is also possible to produce a greenish quartz through irradiation of colorless quartz found within certain types of geodes.

Heated green quartz (true prasiolite) remains green when viewed with a Chelsea.
Irradiated colorless quartz which was altered to green appears reddish with a Chelsea.


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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Sat May 12, 2012 9:47 am 
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Thnaks Barbra, good info!!

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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Sat May 12, 2012 11:04 am 
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:smt023 8)

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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Sat May 12, 2012 11:22 am 
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Dang! Now I have to search under my window for the Chelsea! 8)

Thanks for sharing that with us, Miss B. :D

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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Sat May 12, 2012 2:20 pm 
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Thank you Barbra!
I've just added this info in my GIA Gem identification lab manual...this tip isn't mentioned.

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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Sat May 12, 2012 3:43 pm 
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Dr. Henn presented an excellent talk on quartz treatments.
The presentation reflected his personal experimentation and experience.
The results are currently in print (auf Deutsch) in the latest DGemG publication.
He promised to send me a copy via snail mail.
I'll post specifics when I get the report. :D


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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Sat May 12, 2012 10:27 pm 
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Well, don't that take the cake? lol, it's good for something after all. :)

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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Mon May 14, 2012 5:49 am 
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And now I have to go through "ALL" my prasiolite with my chelsea (IF I can find the filter again...). [-o< #-o :^o :wink:
Thanks Barb! :roll: :lol:

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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Mon May 14, 2012 6:37 am 
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Well, it turned out that I have no prasiolite so I don´t have to look for my chelsea... :oops:
Thought I had some peaces...

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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Mon May 14, 2012 7:27 am 
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Don't have any prasiolite,I will going to buy any , to test them with my Chelsea filter LOL !


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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Mon May 14, 2012 11:51 am 
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I checked out a couple pieces of my prasiolite - a large 9+ carat and a small 3+ carat. They both look slightly pinkish through the Chelsea. I have quite a few more I'll check out and see if I can get any other reaction.

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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Mon May 14, 2012 12:05 pm 
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Image
The arrow above points to the colorless quartz in amethyst geodes which can be irradiated to green.
The amethyst is NOT altered; only the white quartz around it goes green.


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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Mon May 28, 2012 10:39 am 
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as we are talking green quartz,
green quartz from natural heating or natural radiation should be considered a possibility but it's probably very rare if any. These are obtained through man-made treatment.
There's also synthetic green quartz (colored by the same treatments, or colored by dopants)

On the other hand there are green quartz from green mineral inclusions: hedenbergite, chlorite, actinolite, fuchsite...


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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Mon May 28, 2012 11:50 am 
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Excellent update, cascaillou.
Do you have some pictures to post of your examples?
That would be great.


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 Post subject: Re: A Determinitive Use for the Chelsea Filter
PostPosted: Mon May 28, 2012 7:06 pm 
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let's note that when a quartz is coloured (green, blue, turquoise, red, orange, yellow, pink...) by homogeneously spreaded fine mineral inclusions, then the quartz will usually be translucent or opaque, and in my experience, when it's rather transparent (very fine inclusions) then it's not perfectly transparent (slightly blurry)

The green color is most often an herbaceous green, but in some cases you can get very nice green or bluish-green shades.
Here's a beautiful pastel-green shade of chlorite included quartz:
Image

ps: keep in mind that microcrystalline quartz isn't the same as monocrystalline quartz, but both can be coloured by fine mineral inclusions (for instance I've seen green monocrystalline quartz coloured green by fuchsite inclusions, which is different from aventurine which is coloured by the same inclusions but it is microcrystalline quartz form)


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