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Post by gmitch067 on Oct 27, 2017 9:56:04 GMT -5
I found this nice small agate slab piece at the Consolidated Rock and Mineral Shop here in Vacaville - only 1.5X2.5 inch. I was looking to work a 30X40 mm cab, but that size cut out a lot of it's beauty... so I rounded off the sharp edges and made it into a large worry stone - or a small display stone to give as a gift. Question-1: Anybody recognize the pattern enough to be able to ID it? Question-2: What process allows such a beautiful inclusion pattern to form? (I know... a totally newbi question... but I would like to include a description with the gift) ![](https://i.imgur.com/ilB19Puh.jpg) flip side... ![](https://i.imgur.com/8rYTSKhh.jpg)
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Post by rockjunquie on Oct 27, 2017 12:21:27 GMT -5
I don't know about the process of how it was formed, but you have some beautiful sagenite. Well done!
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Deleted
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Post by Deleted on Oct 27, 2017 12:31:12 GMT -5
This is sagenitic agate (often abbreviated as "sagenite"). It could be from Nipomo, or another area - difficult to tell without seeing the original rough. This type of agate starts in voids within or between harder rocks. First needle-like growths (either random, or in acicular "pom pom" clusters) begin to form within the void. There is no mineral known as "sagenite," and the needles can be zeolites, or any mineral that can grow in a needle-like habit (your piece could be something like aragonite). Later, the remaining open space in the void is filled with chalcedony, resulting in sagenitic agate.
In some sagenitic agate, the mineral needles can be partially or totally dissolved away, leaving just the impression of the original mineral. If more chalcedony or some other mineral later replaces the voids once occupied by the needles, then you would have a pseudomorph sagenitic agate. This doesn't appear to be the case with your cabochon.
Often, the needle-like inclusions get surrounded by banded agate, instead of the less common transparent chalcedony, and results in Crazy Lace and other intensely fortified patterns where the sagenitic needles aren't the focus of attention.
I agree: very attractive cab.
PS: the same process is responsible for "rutilated" quartz, where the inclusions are very often not the mineral rutile, but other needle-like mineral growths which have later been encapsulated within macro-crystalline quartz crystals.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
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Post by Sabre52 on Oct 27, 2017 14:28:18 GMT -5
Beautiful cab and great explanation. To me also, it does have the look of Nipomo sagenite....Mel
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fishnpinball
Cave Dweller
So much to learn, so little time
Member since March 2017
Posts: 1,491
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Post by fishnpinball on Oct 27, 2017 14:33:18 GMT -5
Nice cab. There are so many different types of agate formations it is really neat to interpret how some of the different types are created. I love the variety that agates have.
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Post by gmitch067 on Oct 27, 2017 15:06:06 GMT -5
This is sagenitic agate (often abbreviated as "sagenite"). It could be from Nipomo, or another area - difficult to tell without seeing the original rough. This type of agate starts in voids within or between harder rocks. First needle-like growths (either random, or in acicular "pom pom" clusters) begin to form within the void. There is no mineral known as "sagenite," and the needles can be zeolites, or any mineral that can grow in a needle-like habit (your piece could be something like aragonite). Later, the remaining open space in the void is filled with chalcedony, resulting in sagenitic agate. In some sagenitic agate, the mineral needles can be partially or totally dissolved away, leaving just the impression of the original mineral. If more chalcedony or some other mineral later replaces the voids once occupied by the needles, then you would have a pseudomorph sagenitic agate. This doesn't appear to be the case with your cabochon. Often, the needle-like inclusions get surrounded by banded agate, instead of the less common transparent chalcedony, and results in Crazy Lace and other intensely fortified patterns where the sagenitic needles aren't the focus of attention. I agree: very attractive cab. PS: the same process is responsible for "rutilated" quartz, where the inclusions are very often not the mineral rutile, but other needle-like mineral growths which have later been encapsulated within macro-crystalline quartz crystals. @rocks2dust Wow! 'A really nice explanation rocks2dust! Rather than paraphrase you in my gift write-up, I think I will just copy/paste it into a Word doc, get a printout and include it in the gift box. Thank you! Glenn
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Tommy
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Post by Tommy on Oct 27, 2017 17:49:35 GMT -5
Hi Glenn, just to illustrate @rocks2dust's excellent explanation that really needs no illustration - this is a chunk of rock I found in the N.Cady mountains, a place known for beautiful plume agates. This piece had all the makings of a beautiful plume agate growing in a seam between host rocks, but for whatever reason it never got filled in with chalcedony. ![](http://rockshow.rocktumblinghobby.com/i.php?/upload/2017/10/27/20171027154429-5e65e64f-me.jpg) ![](http://rockshow.rocktumblinghobby.com/i.php?/upload/2017/10/27/20171027154430-bb49655e-me.jpg)
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rockpickerforever
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Member since July 2011
Posts: 12,069
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Post by rockpickerforever on Oct 27, 2017 18:04:40 GMT -5
I've got a bunch of stuff like that from the Brenda fieldtrips in years we went to Q. But mine is red!
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Post by gmitch067 on Oct 27, 2017 19:41:45 GMT -5
Hi Glenn, just to illustrate @rocks2dust 's excellent explanation that really needs no illustration - this is a chunk of rock I found in the N.Cady mountains, a place known for beautiful plume agates. This piece had all the makings of a beautiful plume agate growing in a seam between host rocks, but for whatever reason it never got filled in with chalcedony. ![](http://rockshow.rocktumblinghobby.com/i.php?/upload/2017/10/27/20171027154429-5e65e64f-me.jpg) ![](http://rockshow.rocktumblinghobby.com/i.php?/upload/2017/10/27/20171027154430-bb49655e-me.jpg) Mini- Stalagmites and Stalactites! 'Way COOL! I was working with Graveyard Point Plume the other day... asking how to clean it without impacting the integrity of the rest of the slab; forum.rocktumblinghobby.com/thread/80249/clean-rough-slabNow I can see and understand their formation better. Thank you!
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Deleted
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Post by Deleted on Oct 28, 2017 13:57:50 GMT -5
That actually looks like it might make interesting gems, cut to shape and flat-polished. Anyone ever try that? Cabs with angel-wing edges and crystal vugs seem to attract a lot of attention at shows, but don't recall seeing finished pieces that were all-over lacy plume interior (minus any holding agate) like this. As well as plume, I've come across thunderegg interiors where the moss had formed, but not filled with chalcedony/agate. Those definitely were too delicate even to slab, let alone polish, but that Cady plume looks like it could hold up.
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Post by fernwood on Oct 30, 2017 5:49:00 GMT -5
Great piece. LIke what you plan to do with it.
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Post by pghram on Nov 6, 2017 20:46:22 GMT -5
Beautiful cab!
Peace, Rich
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Post by Pat on Nov 6, 2017 20:49:04 GMT -5
gmitch067 I'm so glad you asked, and I am also very glad @rocks2dust answered. Now if someone can tell me at what point serpentine becomes jade, or just what is the relationship..
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