<'))))>< Fish
Cave Dweller
Gone Fishing
Member since April 2005
Posts: 1,838
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Post by <'))))>< Fish on Dec 15, 2018 17:40:18 GMT -5
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Post by vegasjames on Dec 15, 2018 19:00:27 GMT -5
Beautiful. That last one is my favorite.
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Post by MsAli on Dec 16, 2018 8:57:24 GMT -5
I really like the last one as well
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Post by fernwood on Dec 16, 2018 9:48:45 GMT -5
All are great.
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Post by hummingbirdstones on Dec 16, 2018 10:28:26 GMT -5
Nice group of cabs! I like the last one best, too.
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Post by rockjunquie on Dec 16, 2018 10:30:15 GMT -5
A few?? What's a lot? LOL! They are great, but I'm going with the last one, too. What is it?
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<'))))>< Fish
Cave Dweller
Gone Fishing
Member since April 2005
Posts: 1,838
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Post by <'))))>< Fish on Dec 16, 2018 11:16:57 GMT -5
not sure what it is, a friend gave me a small slab, two years ago, and I am just getting around to cab it.
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gemfeller
Cave Dweller
Member since June 2011
Posts: 3,732
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Post by gemfeller on Dec 16, 2018 15:29:48 GMT -5
Good job! My eyes go to Number 4...lapis? Or...
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Post by Bluesky78987 on Dec 16, 2018 19:52:19 GMT -5
Yup, I'm loving all of them but the blue (Lapis? Dumorterite? Azurite?) one is my favorite.
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<'))))>< Fish
Cave Dweller
Gone Fishing
Member since April 2005
Posts: 1,838
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Post by <'))))>< Fish on Dec 16, 2018 20:08:42 GMT -5
the blue one is Azurite
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hummingbirdstones2
fully equipped rock polisher
Vince A., 1958-2023
Member since August 2018
Posts: 1,461
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Post by hummingbirdstones2 on Dec 16, 2018 20:39:36 GMT -5
You sure had a good day. You do good work, and we all know you have great rough.
You're the first person I've seen cut a cab from that Limonite in photo #6. That's a great polish on that stuff - not even a sign of undercutting in the purple spots. We got a chunk of it a few years ago and have never seen another piece of it for sale.
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<'))))>< Fish
Cave Dweller
Gone Fishing
Member since April 2005
Posts: 1,838
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Post by <'))))>< Fish on Dec 16, 2018 21:15:30 GMT -5
had to google Limonite. number 6 cabochon is Bristlecone Pine Forest Oolite
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Post by stephan on Dec 16, 2018 22:24:28 GMT -5
Limonite is the "fire" in fire agate, and can also be the matrix of variscite.
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hummingbirdstones2
fully equipped rock polisher
Vince A., 1958-2023
Member since August 2018
Posts: 1,461
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Post by hummingbirdstones2 on Dec 16, 2018 23:25:25 GMT -5
Yeah, the Bristlecone Pine area. It took us a long time to find that info after buying the rough. A professional lapidary in the business for over 40 years told us later that the pale green color was due to some limonite content. Not being mineralogists, we said "okay"... .
I've always wanted to know more about this material, but good info isn't easy to find. We've been told by a few people now that the area this came from has been closed to collecting.
Have since learned (from real expert) that after the "eyes" get above 2 mm they're "pisolites", and the oolites are smaller than 2mm. We usually just stick with the common usage and call them all oolites.
If anyone has links to more info about this stuff I'd love to read more about it. Too many people in the "real world" blow smoke. That's one thing I like about these forums - no one has anything to gain by BS-ing other people, and everyone is willing to share what they know.
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gemfeller
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Post by gemfeller on Dec 17, 2018 0:56:08 GMT -5
Limonite is the "fire" in fire agate, and can also be the matrix of variscite. My research shows that the iridescent structure in fire agate is goethite, another closely associated iron mineral, not limonite. Both minerals are the product of iron oxidation. Limonite is amorphous, with no crystal structure, while goethite has a fibrous, silky structure. It's the golden "needles" in some amethyst and other crystalline quartzes often mistakenly called cacoxenite. Ironically, goethite was called limonite for many years so it can be confusing.
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Post by vegasjames on Dec 17, 2018 1:34:40 GMT -5
</div> Limonite is not an actual specific mineral. Instead it is a mix of iron oxides and hydroxides. Very common with the copper ores and gold mines. If you have seen some of my copper ore cabs the browns are almost always limonite.
It also occurs in chunks around here all by itself and there is a location of petrified wood just North of here that is almost all limonite.
It can make some really beautiful cabs. I have cabbed several pieces of limonite. One had a pattern that made it look like polished burl wood and the other looks like suede leather.
The brown in this chunk of malachite is limonite.
The golden color in this middle of this vein is limonite.
The gold, red, yellow and brown in this mine is also limonite
And the brown in this cab. As you can see it cab polish very well.
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Post by vegasjames on Dec 17, 2018 1:46:10 GMT -5
Limonite is the "fire" in fire agate, and can also be the matrix of variscite. My research shows that the iridescent structure in fire agate is goethite, another closely associated iron mineral, not limonite. Both minerals are the product of iron oxidation. Limonite is amorphous, with no crystal structure, while goethite has a fibrous, silky structure. It's the golden "needles" in some amethyst and other crystalline quartzes often mistakenly called cacoxenite. Ironically, goethite was called limonite for many years so it can be confusing. From my understanding fire agate is a chalcedony stained by limonite. And the fire is supposedly from both thin layers of limonite and goethite. That would account for the different colors in the "fire".
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Post by stephan on Dec 17, 2018 10:44:43 GMT -5
My research shows that the iridescent structure in fire agate is goethite, another closely associated iron mineral, not limonite. Both minerals are the product of iron oxidation. Limonite is amorphous, with no crystal structure, while goethite has a fibrous, silky structure. It's the golden "needles" in some amethyst and other crystalline quartzes often mistakenly called cacoxenite. Ironically, goethite was called limonite for many years so it can be confusing. From my understanding fire agate is a chalcedony stained by limonite. And the fire is supposedly from both thin layers of limonite and goethite. That would account for the different colors in the "fire". That is what I have read as well. I should have said that it is "one of the sources of 'fire' in fire agate."
It is, also, the yellow in variscite matrix:
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mossyrockhound
fully equipped rock polisher
Member since January 2011
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Post by mossyrockhound on Dec 17, 2018 12:16:29 GMT -5
Great batch of cabs! I like them all. Now I know a little about limonite too.
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gemfeller
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Member since June 2011
Posts: 3,732
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Post by gemfeller on Dec 17, 2018 12:47:03 GMT -5
vegasjames , stephan : Limonite or goethite? I've done a lot of reading about fire agate over the years because I've cut a lot of it and have been curious about the cause of its iridescence. Much conflicting theorizing has been published about it. I rely on the GIA for authoritative information on gems because the organization has the resources, equipment and expertise to do reliable research. So here's the verdict from John Koivula, the GIA's top research gemologist: www.gia.edu/gems-gemology/winter-2015-microworld-dragons-eye-fire-agate
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