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Post by Jugglerguy on Apr 4, 2022 11:37:04 GMT -5
At least I think it's a thunder egg. A friend of mine gave me a bucket of rocks and there are a couple that I believe are thunder eggs. I'd like to cut this one, but I'm not sure if there's a proper way to do it. There's a very obvious "seam" around it. Should I cut along the seam, perpendicular to it, or some other way?   |
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Post by HankRocks on Apr 4, 2022 18:20:15 GMT -5
Rob, In my opinion it appears to me to be a Choyas - Geode from Mexico. I have never tried to figure out cutting plane on Choyas, clamp and cut. For Baker Ranch and other thundereggs I believe the Geode Kid said that cutting perpendicular to the horizontal formation plane of the piece was best. The trick was that some of the pieces shifted in the ground during formation and actual horizontal plane could only be discovered by how it was laying when dug. That's not very practical for non-self dug pieces so i always look for outside rings of planes as they usually form in the horizontal.
Have not seen many Choyas(if yours is indeed a Choyas) with any sort of surface signs of horizontal. Since most are concentric it should not really matter. I would say the ring on yours is a horizontal sign, so if it were me I would cut perpendicular to it.
Did I manage to talk in a complete circle??
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Post by hummingbirdstones on Apr 4, 2022 19:30:43 GMT -5
Rob, In my opinion it appears to me to be a Choyas - Geode from Mexico. I have never tried to figure out cutting plane on Choyas, clamp and cut. For Baker Ranch and other thundereggs I believe the Geode Kid said that cutting perpendicular to the horizontal formation plane of the piece was best. The trick was that some of the pieces shifted in the ground during formation and actual horizontal plane could only be discovered by how it was laying when dug. That's not very practical for non-self dug pieces so i always look for outside rings of planes as they usually form in the horizontal. Have not seen many Choyas(if yours is indeed a Choyas) with any sort of surface signs of horizontal. Since most are concentric it should not really matter. I would say the ring on yours is a horizontal sign, so if it were me I would cut perpendicular to it. Did I manage to talk in a complete circle?? Heck Henry, if I understood it, anyone can!  |
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Post by Rockoonz on Apr 4, 2022 20:24:11 GMT -5
I also think it looks more like a geode of some kind. judging from weight do you think it's hollow? With thunder eggs the preferred direction of cut can vary by the person as they can yield different shapes. If I were to cut it I think I would cut parallel to the ridge feature that appears to go kinda horizontally in your first picture.
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Post by Jugglerguy on Apr 4, 2022 21:18:26 GMT -5
Ok, so far I have one vote for parallel and one for perpendicular. Maybe I should average the two opinions and cut it at 45°. The guy who gave me the rock stopped by today and I asked him. He didn't know what kind of rock it was, but didn't think it would be a thunder egg because he said he doesn't really get too excited about them. There were two other rocks like this in the bucket he gave me. The others don't have the ridge around them. None of them feel lightweight for their size to me. Here's a picture of a chipped spot on the smallest of the bunch.  |
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Post by hummingbirdstones2 on Apr 4, 2022 21:44:55 GMT -5
We've been told to look for a "belly button" on thundereggs that would indicate the point where the secondary minerals would've entered the vug.
I think the reasoning was to find that point and visualize a line from there through the center of the egg. Cutting perpendicular to that line through the center is what was recommended to us. I'm thinking that might correspond to the feature running around the outside of yours.
We've cut a few, but there are people on here who have cut lots more than we have. I'll be reading any of their opinions with great interest.
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Post by HankRocks on Apr 5, 2022 6:54:48 GMT -5
The exposed agate in the 2nd one you posted does appear to be the inside color of a good many Choyas I have cut. Probably try cutting it first. If they are solid it probably does not matter, most I have seen have concentric patterns.
There's always a possibility that the first one is a dud, interesting but not very attractive. Over the years I have sent several to erosion control.
One thing about some of the Thundereggs and geodes, after cutting it you will have a better idea how you should have cut it!!
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Post by Jugglerguy on Apr 5, 2022 8:49:01 GMT -5
Thanks, Hank. It's reassuring to know that I'll have learned something after I screw it up! I'm ok with it being either a thunder egg or a geode. It should be interesting either way.
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rockbrain
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Member since January 2022
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Post by rockbrain on Apr 16, 2022 9:16:02 GMT -5
I've got a couple buckets of various thunderegg/geodes to cut. I'm doing them a few at a time. Sometimes I cut off center. You can take a slice for cabs out of the middle and end up with 2 halves and a slab. The halves are only slightly smaller after the slice.
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Post by Jugglerguy on Apr 17, 2022 10:00:14 GMT -5
I've got a couple buckets of various thunderegg/geodes to cut. I'm doing them a few at a time. Sometimes I cut off center. You can take a slice for cabs out of the middle and end up with 2 halves and a slab. The halves are only slightly smaller after the slice. That's a good idea. Thanks for the suggestion. |
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