Lapidaryforum.net
Let's Rock => Rock Talk => Topic started by: ileney on January 06, 2018, 02:34:55 PM
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40+ years ago, a good lapidary friend of my dad's passed away and he was given by the widow this massive geode that looks sort of like a brain, but also is about the exact color and size of a largish canteloupe, along with some equipment and other things she didn't know what to do with. It weighs a ton. It was just boxed and mailed to me from Florida. My dad says his friend only bought the best material available (and it is from Brazil, as you would assume based upon the age and appearance). Based upon its weight, I am not too sure it has anything but solid rock inside it, though my dad seems convinced it does and is from an area that was yielding really great stuff at the time, including supposedly amethyst and citrine. My 10" saw is not going to make much headway on this 6.75" by 6.25" geode but I do have one lapidary friend who is quite inventive and will ask him if he can possibly devise a way to cut it open. Any thoughts on determining what might be inside? Any thoughts on cutting it open that don't involve taking it to another state and paying absurd sums? Or shoud I just hold onto it? The suspense may kill me.
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It doesn't look like brazilian and first impressions, not an agate either. It looks like a concretion (which could have a crystal pocket center) or septarian nodule.
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I agree, possible septarian. I have cut hundreds of Brazilian agates and they all had an agate rind.
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Hmm... he did give me a very impressive huge septarian that was already split and polished, but I gave it to a lapidary friend as I am not a huge fan of those. I can’t recall what the rind on it looked like. I do have a fair number of smaller agate geodes and I agree that their rinds are not dusty like this. I’m slapping myself on the head because it didn’t even occur to me that was significant.
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You could always try splitting things that are too big for your saw. I’ve had surprisingly good luck with this
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My money would be on white solid crystal center as is so typical for Brazilians. Sometimes the rind is variable in brown layers before you expose the white crystal core.
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Another thing to take into consideration towards septarian and not brazilian are the segments which are not in Brazilian but are easy ways to distinguish Septarians. The 2 images you can see easily the valleys between each area.
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geothermal-Mud ball, Hollow like a geode. just not a hot flow gas pocket as in basalt flows.
pot of hot mud cooling with hollows in in the mud.
With lime stone traps / ( Strata ) up hill washing down forming sedimentation formation in the void, the concretion voids in the MUD-POND sink hole. or a hot swamp.
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I'm pretty well convinced by these points that it is a Septarian and was assumed to be Brazilian because it was in with the geodes.
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Whatever it turns out on cutting it is always like Christmas opening them up. Sure to be amazing.