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 Post subject: Re: Green Zircon
PostPosted: Wed Sep 16, 2020 2:33 pm 
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But all Low Zircons are some shade of green as I understand it.

So:

All Low Zircon are Green

but

All Green Zircon are not Low Zircon

And that is the basis for the confusion.


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 Post subject: Re: Green Zircon
PostPosted: Sun Dec 06, 2020 1:05 am 
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1bwana1 wrote:
But all Low Zircons are some shade of green as I understand it.

So:

All Low Zircon are Green

but

All Green Zircon are not Low Zircon

And that is the basis for the confusion.


This isn't what I've found. You can get greenish-yellow or brown colours in Zircons that would also be considered low-type.

As was mentioned by Tim earlier in this topic:
Tim wrote:
Frank and I discussed this recently in one of the chats.
this was the outcome:
All green zircons are metamict
not all metamict zircons are green.


Metamict zircons are the low-type zircons due to the damage the radioactivity has had on their crystal structure. Then again it would depend on what you would consider the point for a zircon to be labelled as low-type vs medium or high.

I just came across a yellow zircon with a B/D ratio of around 0.4 - 0.5 so it's birefringence would probably have been around 0.015 - 0.02. Much lower than the high type which is usually in the 0.05 - 0.059 range but not completely 0 either so it would depend on where you put your line for low, medium or high type.


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 Post subject: Re: Green Zircon
PostPosted: Sat Jan 02, 2021 7:47 pm 
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S. Rautiainen wrote:
1bwana1 wrote:
But all Low Zircons are some shade of green as I understand it.

So:

All Low Zircon are Green

but

All Green Zircon are not Low Zircon

And that is the basis for the confusion.


This isn't what I've found. You can get greenish-yellow or brown colours in Zircons that would also be considered low-type.

As was mentioned by Tim earlier in this topic:
Tim wrote:
Frank and I discussed this recently in one of the chats.
this was the outcome:
All green zircons are metamict
not all metamict zircons are green.


Metamict zircons are the low-type zircons due to the damage the radioactivity has had on their crystal structure. Then again it would depend on what you would consider the point for a zircon to be labelled as low-type vs medium or high.

I just came across a yellow zircon with a B/D ratio of around 0.4 - 0.5 so it's birefringence would probably have been around 0.015 - 0.02. Much lower than the high type which is usually in the 0.05 - 0.059 range but not completely 0 either so it would depend on where you put your line for low, medium or high type.

I am not a gemological scientist, but this seems to be the splitting of the finest of hairs. Or is that really what zircons in these categories come down to?

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 Post subject: Re: Green Zircon
PostPosted: Sun Jan 03, 2021 12:48 am 
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glhays wrote:
I am not a gemological scientist, but this seems to be the splitting of the finest of hairs. Or is that really what zircons in these categories come down to?


What do you mean come down to?

Zircon stones are, at least in my opinion, very interesting stones so I completed a bit of research on top of what was being taught in my gemmology program. To my knowledge, however, there hasn't been a consistently specific way that people classify them based on their birefringence or anything. It is generally accepted that there are low and high type zircons and most people recognize medium zircons but depending on your source of information I've seen different classifications of what is high vs low type.

If you want to look at it a little more technically, basically anything that isn't a high type zircon (however you might classify it) is technically metamict to an extent because it has had some radiation damage to make it something other than high type zircon.

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 Post subject: Re: Green Zircon
PostPosted: Sun Jan 03, 2021 2:19 am 
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I guess what meant was the colors green verses greenish yellow or yellowish green and so forth, determinations of low high. That's all. Just trying to understand a bit better.

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