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 Post subject: Montana Sapphire GIA Field expedition
PostPosted: Thu Feb 25, 2016 4:04 pm 
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New video on the GIA website about Montana Sapphire Mining. Enjoy.

Nathan

http://www.gia.edu/gia-news-research/ro ... -sapphires

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 Post subject: Re: Montana Sapphire GIA Field expedition
PostPosted: Thu Jun 02, 2016 6:17 am 
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Dr. Aaron Palke and Nathan Renfro performed extensive colorimetric tests on samples to analyze the color change and the factors that influence it. They determined the range of stone sizes that maximize the color change, although the difference is not significant enough, according to some definitions, to be the classified as an actual color change.

Admin note: The study toptanzanite refers to above does not apply to Montana Sapphire, but garnet. See Nathan's post below


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 Post subject: Re: Montana Sapphire GIA Field expedition
PostPosted: Sat Jun 04, 2016 1:21 am 
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Great video, thanks for posting. Brings back some great memories for me. I did some interesting work with Montana sapphires, mining, and processing back in the 1990's. I love the area, and the stones.

Steve


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 Post subject: Re: Montana Sapphire GIA Field expedition
PostPosted: Sat Jun 04, 2016 1:36 pm 
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That's awesome! I am from Montana and lived in Helena. Years ago, we used to go to the sapphire mines for Yogo Sapphires. Back then they were not in demand and as expensive as they are now. My dad has a color change Yogo Sapphire that he bought for my mom. It is beautiful!


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 Post subject: Re: Montana Sapphire GIA Field expedition
PostPosted: Sat Jun 04, 2016 11:02 pm 
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Um... the Yogo Sapphires are of course on the other side of the state, near Utica. The sapphire from the mines near Helena are very nice - but they aren't Yogos. I have been to the mines in Helena and around Philipsburg, but the Yogo mines haven't been accessible to rockhounds for a VERY long time - my family went there in the 60's and they had already been closed for a while.


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 Post subject: Re: Montana Sapphire GIA Field expedition
PostPosted: Sun Jun 05, 2016 12:28 am 
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Yes i do remember where the Yogo mines are. We had one sapphire mine outside of Helena that was a smaller one that we used to take family to. I also knew someone who had a small gold mining operation and we used to pan for gold. Fun times and great memories!


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 Post subject: Re: Montana Sapphire GIA Field expedition
PostPosted: Mon Jun 06, 2016 1:06 am 
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toptanzanite wrote:
Dr. Aaron Palke and Nathan Renfro performed extensive colorimetric tests on samples to analyze the color change and the factors that influence it. They determined the range of stone sizes that maximize the color change, although the difference is not significant enough, according to some definitions, to be the classified as an actual color change.



This was for garnets, not Montana sapphires. I think the above post made it to the wrong thread somehow.

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