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Non-siliceous

Hello, all,
I have been looking for these in the house for awhile.. they exhibit classic agate banding patterns, but the material they are made of is DEFINITELY not siliceous!

Handling them leaves a white, talc-like residue on my hands, and they quickly absorb any water thats dropped on their surface.. Due to this "sponge" action, I hav'nt got much effervescence from vinegar. (Will detach a small piece and put some stronger acid on it).
I have always been told that agate formation came about due to the intermittent flows of hydrothermal silica solutions into spaces in a solid or semi-solid lava flow, building up the typical agate layers (like a tree's growth rings). But this is something else... maybe the agates "rings" are pre-formed" out of a carbonate material, and then replaced by the hydrothermal silica. ??? Any comments??

There is a gentleman at Stanford nicknamed "The Agateer", who I would love to comment on this...but he's a difficult man to reach.. ( Prof, I Hope you see this !!)

P.S. See the pictures submitted at the same date in the "photo" section..

From tony goffe - November 21, 2012 at 01:40:24
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Message: 70538



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