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Post by Toad on May 2, 2006 20:46:23 GMT -5
Got this at the auciton I just won. Most of it appears to be chevron amethyst, but the point looks to be mottled brown. Very odd:
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Rockygibraltar
fully equipped rock polisher
Member since February 2006
Posts: 1,404
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Post by Rockygibraltar on May 2, 2006 20:47:06 GMT -5
That is Amethyst from Thunderbay Ontario. The reddish brown you see on the top is from iron oxides. It's the only place in the world that this type of Amethyst comes from.
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earthdog
Cave Dweller
Don't eat yellow snow
Member since June 2006
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Post by earthdog on May 2, 2006 21:45:11 GMT -5
I just read that all Amethyst is formed and colored by small amounts of iron (approx. 40 parts per million). Amethyst color develops when iron-containing quartz is exposed to ionizing radiation. It contains a little more iron oxide than any other variety of quartz, and its color arises from this iron content. Even quartz crystals from South Carolina have the redish brown iron stains. Same with Amethyst from brazil. I beleive that Ame crystal just hasn't had the iron stain removed yet. Rocky, where did you get the info on thats the only place in the world the iron stained Ame comes from? Notable deposits with iron stains are found in Brazil, Uruguay, Ontario, and North Carolina.
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Rockygibraltar
fully equipped rock polisher
Member since February 2006
Posts: 1,404
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Post by Rockygibraltar on May 2, 2006 23:51:40 GMT -5
Earthdog, the first place I had heard this is from a miner in one of the Thunderbay mines. After reading your post I did a little digging around and found the same information that you gave documented in a number of different places. However, amethysts from different localities do have differing characteristics. The link below is one source of info about the differences between the amethysts from around the world. If you scroll down you can compare them. This source notes that this particular red hematite inclusion is unique to Thunderbay amy. www.galleries.com/minerals/gemstone/amethyst/amethyst.htm
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