dingo2
off to a rocking start
Member since August 2022
Posts: 5
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Post by dingo2 on Aug 16, 2022 22:32:09 GMT -5
I am completely new to rockhounding as a hobby, but am pretty experienced in fossil and artifact hunting, so its not too far removed from my roots. I haven't ever really been compelled to go anywhere and look exclusively for rocks, but I had the opportunity recently to go to an area that produces nephrite jade and even jade artifacts. I was hoping for a beautiful nephrite celt, and athough that didn't happen, I am very happy with the pieces I found that I believe to be nephrite. Eventually I will do a specific gravity test to verify whether or not they are serpentine. The main problem I have (assuming its not serpentine) is that I am not exactly sure what I should do with these pieces. I've seen how the best colour of the stone is exposed by cutting and polishing, but I really would like to avoid cutting them, as I like them as boulders. Some of them (such as the more blue one) seem to have more vibrant colour below the surface and I would like to know if there are any good methods of sanding or polishing that anybody would recommend. I know nephrite is a very tough material so I assume this makes things more difficult. The third image isn't mine, but a piece of nephrite that has clearly been ground to expose the more colourful material under the surface. I'd be interested in doing something like this if I knew the method used. Anyways, I'd appreciate some pointers from people who can help me make these stones as beautiful as possible without cutting them. Let me know if you have any ideas!
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Post by Pat on Aug 16, 2022 23:28:57 GMT -5
Interesting! I cannot help here, but the first photo looks like a mask with a face. I'm curious about the stories behind the first, and the last photos.
Welcome from California!
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dingo2
off to a rocking start
Member since August 2022
Posts: 5
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Post by dingo2 on Aug 17, 2022 0:03:45 GMT -5
Thanks Pat! The first photo is one of the boulders I found, and its definitely the most blue piece of (supposed) nephrite that I found. I'm hoping the whole piece is that lighter blue colour under the surface. The third picture is a photo I found from a website that was selling it as an artifact, though I am skeptical of this claim. Regardless, I am interested in doing something similar to the pieces I collected. This is a picture of the genuine nephrite celt artifacts that have been found in the nearby area. Ancient humans were able to saw and polish them, so hopefully I can too. albertashistoricplaces.files.wordpress.com/2016/08/illustration-prep-jade-nephrite-edit.jpg
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Post by liveoak on Aug 17, 2022 6:23:50 GMT -5
Welcome from NW Florida dingo2. A couple of years ago I purchased a bunch of Washington State "River Jade". My experience in TRYING to polish it, is that SIC works better than diamond. Maybe others more experienced will have better advice. Patty
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Deleted
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Member since January 1970
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Post by Deleted on Aug 17, 2022 7:19:59 GMT -5
Bob has experience with nephrite he could probably give some advice.
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Post by Rockoonz on Aug 17, 2022 10:41:51 GMT -5
Testing for serpentine can start with a hardness check, a steel knife blade will scratch serpentine if you push hard, jade will show a stripe from steel removed from the blade. Grossular garnet or Californite like the stuff from Happy Camp will require a specific gravity check. The general feel of the surface of is also a way to sort it from green rocks, the waxy stuff that oxidizes to the surface that many can feel. In Asia jade hunters in rivers will walk across a river barefooted and feel when they step on jade, at least that's the story.
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gemfeller
Cave Dweller
Member since June 2011
Posts: 3,773
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Post by gemfeller on Aug 17, 2022 12:34:59 GMT -5
Testing for serpentine can start with a hardness check, a steel knife blade will scratch serpentine if you push hard, jade will show a stripe from steel removed from the blade. Grossular garnet or Californite like the stuff from Happy Camp will require a specific gravity check. The general feel of the surface of is also a way to sort it from green rocks, the waxy stuff that oxidizes to the surface that many can feel. In Asia jade hunters in rivers will walk across a river barefooted and feel when they step on jade, at least that's the story. I've heard the same story about searching for California jade in streams barefoot. There's some reason to think it's true. Jade has very high thermal conductivity and is persistently cold to the touch. It takes a longer time to warm in the hand than look-alikes. The idea is that some people can tell the temperature difference between jade and other stones by finding stones that register colder than others barefoot.
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dingo2
off to a rocking start
Member since August 2022
Posts: 5
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Post by dingo2 on Aug 17, 2022 13:27:00 GMT -5
I have tried a variety of methods that I've read about for identifying nephrite jade, though I think some of them are more like heuristics.
I read that nephrite should have a metallic ringing round when struck with a rock or hammer, and most of the pieces I collected had this distinct ringing sound. I believe this is due to the density of the material. Interestingly though, I noticed that the pieces that had a more vibrant green jade colour had less of a ringing sound than some other pieces that appeared to me to be lower quality nephrite.
I also read that serpentine should make a magnet stick to it, and nephrite generally will not. Most of the pieces I collected did not attract a magnet, but a couple did. I also read that nephrite can contain ferrite in it, so I assume this method is not perfect.
All of the boulders seemed to be very dense to me when I was hauling them out, but I wont know for sure until I do a specific gravity test. I knew about the steel scratch hardness test, but I had always seen people do this test after making a cut, so I had assumed it wasnt diagnostic when done on the surface on the stone.
I wont have access to these boulders again until two weeks from now, so we'll have to wait until then to try the scratch test and the specific gravity test.
In the meantime, hopefully I can get some more info on what to do for grinding/polishing these stones. I appreciate the tip about SIC. I have also read that you're supposed to use polishing compounds typically used on metals for nephrite (such as Zam). In addition to that, nephrite is supposed to be easy to damage if the stone heats up while polishing and does something known as "orange peeling". I've seen some people say that you never want to let it get too hot to touch, or orange peeling is a real risk.
I'm assuming that some of the things I've read along the way will be wrong, so if anything I said here seems wrong please let me know.
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rockbrain
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Member since January 2022
Posts: 2,496
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Post by rockbrain on Aug 17, 2022 14:37:48 GMT -5
I hadn't heard of serpentine being magnetic. I've got a few hundred pounds in my yard so I tried it out. Much to my surprise it is magnetic. I wasn't expecting that, thanks for the info.
BTW there's some pretty good info on the forum on polishing jade if you do a forum search.
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dingo2
off to a rocking start
Member since August 2022
Posts: 5
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Post by dingo2 on Aug 17, 2022 23:32:52 GMT -5
I hadn't heard of serpentine being magnetic. I've got a few hundred pounds in my yard so I tried it out. Much to my surprise it is magnetic. I wasn't expecting that, thanks for the info. BTW there's some pretty good info on the forum on polishing jade if you do a forum search. Thanks. I have been gradually reading through old threads and this is the most useful I've found so far. forum.rocktumblinghobby.com/search/results?captcha_id=captcha_search&display_as=0&page=8&search=Search&what_all=river%2Bjade&who_only_made_by=0Right now my current idea is to use an angle grinder with a diamond cutting wheel and remove some irregularities in the surface, and then use diamond polishing pads and see how it ends up. I'm not sure how smart of an idea this is. I have a few lingering concerns though: How does this method mitigate orange peeling? If it doesnt, what can I do to avoid it? I had thought that you were supposed to use a polishing compound like Zam after everything else. Is this not necessary? I have read conflicting statements on whether you should let nephrite get hot while polishing. Is there no consensus on this?
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Post by Rockoonz on Aug 18, 2022 8:24:33 GMT -5
I have a few lingering concerns though: How does this method mitigate orange peeling? If it doesnt, what can I do to avoid it? Light touch starting at 600 grit will help. If you can find a grinder with variable speeds and slow it down that will also help.I had thought that you were supposed to use a polishing compound like Zam after everything else. Is this not necessary? Zam is for softer stones like Turquoise and Variscite, but since it also has a wax like element to it you may get a bit of polishing effect like waxing paint on your car.I have read conflicting statements on whether you should let nephrite get hot while polishing. Is there no consensus on this? Once you are past sanding and you're just polishing, heat won't cause a problem in most materials as long as they are solid. Of course, copper ore stuff and opal you don't want to heat up. I would not use a grinder that is not designed to be used wet, and would gear up with a mask, ear protection, and safety glasses as well.
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dingo2
off to a rocking start
Member since August 2022
Posts: 5
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Post by dingo2 on Aug 18, 2022 16:08:10 GMT -5
I'm reading about using angle grinders to polish stone but I'm thinking mine might not be right for the job. It runs at a no load 10000rpm which sounds like it is too fast for diamond polishing pads. Are there any recommendations for what pads to get, or what grinder to get?
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Post by Mel on Aug 26, 2022 14:35:14 GMT -5
What I was told about jade was to use heat & cerium on a leather pad. How true, I do not know -- while I have a bunch of it, I haven't bothered trying anything with it yet.
As for grinding, most lapidary equipment runs around ~1750 RPM. For pads etc, I'd check Kingsley North or The Rock Shed. Also, if you plan to use a grinder, make sure you use it WET. Dry grinding is a bad time for your equipment, your lungs and the stones.
Please share your results!
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