gemfeller
Cave Dweller
Member since June 2011
Posts: 3,813
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Post by gemfeller on Nov 4, 2013 12:51:22 GMT -5
1dave, I'm not the expert here, nor am I a scientist. But I am very familiar with the scientific method, i.e., the formation of a theory which is then defended against critical peer review. I recently read Mr. Campos-Venuti's new theory and as a layman (with a whole lot of field collecting and observational experience like yours) found it quite compelling. But I'm well aware of competing theories and know his ideas will be very critically vetted. He's the person you should be directing your comments to. As an experienced volcanologist and editor of a prominent Italian gemological publication he's more than capable of defending his own views.
I posted his comments only as food for thought and discussion. If you look at pages 130 and 131 of his book you'll see images of channels quite similar to those in the Deming image you posted. I believe (but am not certain) he was referring only to the plane banding within the channel, not to the channel itself).
However I'm not here to defend him. He's quite accessible by email although he's probably pretty busy preparing for Tucson 2014. If you have the chance you should visit him there -- he has some fascinating specimens.
Rick
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Post by 1dave on Nov 4, 2013 14:42:56 GMT -5
1dave, I'm not the expert here, nor am I a scientist. But I am very familiar with the scientific method, i.e., the formation of a theory which is then defended against critical peer review. I recently read Mr. Campos-Venuti's new theory and as a layman (with a whole lot of field collecting and observational experience like yours) found it quite compelling. But I'm well aware of competing theories and know his ideas will be very critically vetted. He's the person you should be directing your comments to. As an experienced volcanologist and editor of a prominent Italian gemological publication he's more than capable of defending his own views. I posted his comments only as food for thought and discussion. If you look at pages 130 and 131 of his book you'll see images of channels quite similar to those in the Deming image you posted. I believe (but am not certain) he was referring only to the plane banding within the channel, not to the channel itself). However I'm not here to defend him. He's quite accessible by email although he's probably pretty busy preparing for Tucson 2014. If you have the chance you should visit him there -- he has some fascinating specimens. Rick Ditto! Dave
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Nov 4, 2013 15:42:20 GMT -5
but how does the entire inner surface get coated equally, as tho' there's no gravity?
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Post by 1dave on Nov 4, 2013 16:57:45 GMT -5
but how does the entire inner surface get coated equally, as tho' there's no gravity? In my mind's eye, I see silica tetrahedra adhering to the outer walls, the tetrahedra in the fluid flying around in Brownian Movement oblivious to gravity, being caught by the already attached and cooler (at least slower) tetrahedra. As they crystallize, they generate heat, briefly stopping the process, then a new layer begins to form. Dave
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gemfeller
Cave Dweller
Member since June 2011
Posts: 3,813
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Post by gemfeller on Nov 4, 2013 16:59:48 GMT -5
I humbly suggest that the book answers such questions far better than I can. I'm still absorbing a lot of the technical information he presents and can only say that he deals with the matter of gravity in detailed fashion in several examples, especially in the formation of mosses and plumes.
He believes the first chalcedony layer in a nodule starts with the cavity filled with a solution of silica in water. When it dries it leaves a thin layer of chalcedony that sticks to the walls. He believes that agate nodules form from silica gel, and for thick chalcedony layers to form the cavity must be filled up, then dried repeatedly. The hydration and desiccation are related to seasonal cycles of precipitation and drying. At least that's how I interpret it. Band or layer formation is a separate process.
Rick
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Post by rockpickerforever on Nov 4, 2013 17:08:55 GMT -5
Awesome! It looks like a parasite burrowing its way into its host - shiver...
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Post by pghram on Nov 5, 2013 15:02:42 GMT -5
That's another nice agate, very beautiful.
Rich
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snuffy
Cave Dweller
Member since May 2009
Posts: 4,319
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Post by snuffy on Nov 5, 2013 22:25:33 GMT -5
Found another tonight,guess these aren't too rare! snuffy
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