Lapidaryforum.net
Let's Rock => Identifications of Materials => Topic started by: Kaljaia on May 04, 2020, 07:54:39 AM
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So I had a fun moment over on Facebook posting this on the NW Rockhounds page. I stated it isn't carnelian. Since most of that group is based in the PNW in carnelian-rich areas, it may be the primary form of red and colored agate they've interacted with. Most of them replied that they thought it was still carnelian because it's colored red. I still don't believe this fits the definition of carnelian, as the color comes from a dense flecking of inclusions, the material is fresh from its host rock and is probably a tegg tube core, as opposed to an iron-staining leaching through an agate formed in basalt.
At any rate, what do you all think, and how do you define carnelian as opposed to red-colored agate? Images are brighter than real life, but not by a ton. This thing is vivid in direct sunlight. Wasco county material. If I hadn't picked it up off the dirt myself I'd have thought it was dyed. There's a tiny rhyolite outcrop that is producing these in association with thunder eggs.
(https://66.media.tumblr.com/6fced976e075799a8ca20f75c90a66f3/219bd263c6d568ca-6c/s2048x3072/ce503eb485f1ddd7beefe9cc96b90ab57e26b862.jpg)(https://66.media.tumblr.com/bc30bd3f0269eadb8cfbb9c71fb36d7c/219bd263c6d568ca-b8/s2048x3072/937b7e609b5a9c1de7c2c4d3197fe00d9d6b73e5.jpg)
(https://66.media.tumblr.com/fc22825d8cb39281ce3f2a76c2df69a4/219bd263c6d568ca-28/s2048x3072/f92fc6458d307e48fc5ac4dfc9c04d256ebdd420.jpg)(https://66.media.tumblr.com/618d0755075b4339b809fefa47d1a3a1/219bd263c6d568ca-7a/s2048x3072/8875a659e5e61ef59a8ff7348afd508758620777.jpg)
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Your coloration seems to be in layers which would be agate. Carnelian is massive chalcedony without discernible layers by naked eye. Most carnelians in the trade are impregnated with iron which is easy to do then heat treated.The heat treating is often very superficial as the heat has only changed the outer few mm of the preformed stones in most cases. The carnelian bead business in India has traditionally used naturally iron infused chalcedony which is heat treated multiple times before the bead is finished. Washington carnelian is especially superficial in color .When you cut the red surface down a few mm you find just yellow iron infused chalcedony which has to be heat treated to get the red color. There are very few exceptions but lots of experts who fantasize about the rough they collect without putting it to the saw and wheel to determine it's quality.
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Sure is beautiful material...
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So red banded agate it is, and beautiful colors at that! I learn something new each day I access this board. Thanks.
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As Lithicbeads says, most carnelian is heat-treated. It's also chalcedony, not agate, though as the following points out red or reddish chalcedony without banding can be found in some agates. I think the generally accepted definition of agate is "chalcedony with banding." For reference:
http://www.quartzpage.de/carnelian.html
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That's a beautiful piece of red banded agate! :icon_sunny:
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Yes, you are right that it’s not carnelian (and also, it’s lovely! )
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It is still one of the most beautiful and unique pieces I have seen of late!!!
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I think those colors are actually prettier than carnelian, but some of those oranges are great, and work well with others stones.