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Is this jadeite or nephrite?
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winn




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PostPosted: Aug 03, 2017 10:17    Post subject: Is this jadeite or nephrite?  

Hi everyone -- new member here, but I am guessing I'll be popping in fairly often since I recently moved to Seattle and feel a bit overwhelmed by the variety of stones one can find on the beaches here.

First up is a stone I found a few days ago that I suspect may be jade (either jadeite or nephrite, not sure how to tell them apart). It's harder than steel, but that's the only scratch test I have done. I gather that measuring SG would probably be helpful, but I've never done that before and don't have any special equipment to do so. Would it be helpful to get a rough estimate using a scale and measuring displacement in a liquid measuring cup, or would that be too imprecise to be worthwhile?

Photos are attached.



IMG_20170802_104802.jpg
 Mineral: Nephrite or jadeite?
 Description:
Puget Sound
 Viewed:  2504 Time(s)

IMG_20170802_104802.jpg



IMG_20170802_104806.jpg
 Mineral: Nephrite or jadeite?
 Description:
Puget Sound
 Viewed:  2498 Time(s)

IMG_20170802_104806.jpg



IMG_20170802_104829.jpg
 Mineral: Nephrite or jadeite?
 Description:
Puget Sound
 Viewed:  2504 Time(s)

IMG_20170802_104829.jpg


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alfredo
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PostPosted: Aug 03, 2017 11:46    Post subject: Re: Is this jadeite or nephrite?  

Hello Winn, and welcome to the FMF forum.

Several years ago I wrote a brief article on distinguishing nephrite from jadeite, here: https://www.mindat.org/article.php/883/Jade
- more of a mineralogical point of view, as gemmologists will approach the topic with a different point of view.
I'm sure you already know some of the information presented, but I hope you find a few useful tips on distinguishing these.

Alfredo
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winn




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PostPosted: Aug 03, 2017 11:54    Post subject: Re: Is this jadeite or nephrite?  

Thanks! Is there any easy way to verify whether this specimen is even one of the two? I'm guessing there are many types of stone that are slightly translucent, greenish, waxy looking, and harder than steel....
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John S. White
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PostPosted: Aug 03, 2017 11:56    Post subject: Re: Is this jadeite or nephrite?  

Am curious to know where you found it.
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winn




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PostPosted: Aug 03, 2017 12:15    Post subject: Re: Is this jadeite or nephrite?  

It was along a beach in West Seattle on Puget Sound, where I had been collecting agates, jasper, and beach glass when it caught my eye. There are a huge variety of different kinds of stone on that same beach, many of them volcanic/igneous in origin (presumably from Mt. Rainier's previous eruptions). About half the rocks look to be gneiss/granite/quartzite and then many that are far beyond my ability to identify other than "looks igneous to me."
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PostPosted: Aug 03, 2017 12:33    Post subject: Re: Is this jadeite or nephrite?  

alfredo wrote:
Hello Winn, and welcome to the FMF forum.

Several years ago I wrote a brief article on distinguishing nephrite from jadeite, here: https://www.mindat.org/article.php/883/Jade
- more of a mineralogical point of view, as gemmologists will approach the topic with a different point of view.
I'm sure you already know some of the information presented, but I hope you find a few useful tips on distinguishing these.

Alfredo


Very good/detailed article Alfredo! (not that I have much knowledge of Jade)

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winn




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PostPosted: Aug 03, 2017 12:37    Post subject: Re: Is this jadeite or nephrite?  

I just thought I'd add a couple photos showing the stone edge-on in case that helps with ID (though it sounds from what I've read that visually ID'ing isn't really possible).


IMG_20170803_102916.jpg
 Description:
 Viewed:  2431 Time(s)

IMG_20170803_102916.jpg



IMG_20170803_102910.jpg
 Description:
 Viewed:  2434 Time(s)

IMG_20170803_102910.jpg


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alfredo
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PostPosted: Aug 03, 2017 14:08    Post subject: Re: Is this jadeite or nephrite?  

Pierre, Thank you for the kind comment.

Winn, I occasionally visit my sister on Whidbey island, where I see some of the same kinds of beach stones you see in Seattle. One likely possibility for your rock would be a fine-grained quartzite, colored greenish by microscopic chlorite, but the older I get and the more I learn, the less confident I feel about making an ID from a photo. Jade is possible too, and western Washington has quite a number of serious jade hunters. It's a little too rounded for jade, in my opinion. Because of jade's extraordinary toughness, pebbles of it tumbled in running water are rarely so rounded; their shapes tend to be rather more irregular. But you could definitively exclude quartz, if it isn't quartz, by measuring the density.

I contacted a western Washington jade hunters' club once via Facebook. Their members seem not to have much contact with the regular mineral collecting community there as their interests are exclusively in jade and nothing else.
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winn




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PostPosted: Aug 03, 2017 14:54    Post subject: Re: Is this jadeite or nephrite?  

I tried using the best tools I have on hand to measure the density. While I have a fairly accurate scale (to nearest 1g, just calibrated it with 100g weight), unfortunately I have no accurate way to measure the volume. The best I have is a kitchen measuring cup with 25ml increments. The good news is that when I gave it a shot, the stone appears to have displaced precisely 50ml of water, so the only error margin on that measurement is how inaccurately drawn the lines are (optimistically... +/- 5ml?).

So, taken with a grain of salt, this is my measurement:
Mass: 155g
Volume: 50ml

So if my math is right that's a specific gravity of 3.1, though if you include a +/-5ml error margin then that's a range of ~2.8 to 3.4.

Assuming it's not just completely inaccurate, this seems a little high for quartzite, a little low for jadeite, right? If there's even a tiny bit more error, though, it seems like it could overlap with either of them.

What tool(s) should I be purchasing if I want to be able to measure SG accurately in the future?
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winn




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PostPosted: Aug 03, 2017 15:19    Post subject: Re: Is this jadeite or nephrite?  

OK, I just tried what is probably a more accurate way,.

I placed a completely full glass of water in a bowl (taring first for the bowl only). I then gently added the stone to the glass, and carefully removed the glass from the bowl without spilling any additional water. I did this measurement three separate times and got 48g of water each time. Assuming my tap water is ~1g/ml, this would yield a density of 3.2, ruling out quartz/quartzite.
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alfredo
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PostPosted: Aug 03, 2017 15:19    Post subject: Re: Is this jadeite or nephrite?  

Winn, Perhaps you could get a better volume calculation with the simple equipment you have already: Put a styrofoam cup on your scales, and fill it with just enough cold water so that you can immerse your stone in it without it touching the sides. Record the weight of cup + water. Then hang the stone on a thin thread, as thin as possible, and hang it into the water, completely submerged, but not touching the bottom or sides of the cup. The apparent weight of the water will go up by the amount of displacement.

So, for example, if the cup and water originally weighed 249 grams, but it went up to 299 grams when you hung the stone in it, then you have displaced 50 grams of water, or 50 cubic cm. It's not totally accurate of course, for several reasons, but it will give a better result than what you get by observing the increase in water level. Perhaps you'll get to +/- 2% accuracy instead of 5% or worse.

(Edit: You beat me to it, posting while I was writing. Try it this other way too, for additional confirmation. I'm beginning to think you might indeed have found jadeite.)
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winn




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PostPosted: Aug 03, 2017 15:39    Post subject: Re: Is this jadeite or nephrite?  

Aha! OK, so using the suspension method (with sewing thread), I took three separate measurements, and got 51g, 52g, and 52g. So, that would be a SG of 2.9/3.0.

According to Wikipedia at least, this seems a little low for jadeite, more in the range for nephrite?
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alfredo
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PostPosted: Aug 03, 2017 15:46    Post subject: Re: Is this jadeite or nephrite?  

Oh, I forgot to mention that it's best to add a couple drops of dishwashing detergent to the water, which increases the wettability of the rock, otherwise you can have bubbles or an air film around the rock and thread on immersion, leading to a slight apparent lowering of the density.

Might be nephrite. Or you might have an impure jadeite, mixed with albite, for example, which would give a lower density. Do you have more than one such stone (so you could sacrifice a lesser piece for a hammer test and try melting a splinter for a fusibility test)?

Other, known, localities for jadeite in Washington state:
https://www.mindat.org/minlocsearch.php?frm_id=mls&cform_is_valid=1&cf_mls_page=1&minname=jadeite&region=washington
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winn




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PostPosted: Aug 03, 2017 16:00    Post subject: Re: Is this jadeite or nephrite?  

I tried that and got 51g/51g/52g, so I'm thinking with this stone and thread the difference is minimal.

One last post -- photos showing both sides held against a halogen track light (brightest bulb in my house), to show the color and translucence a little better.

Edit: Sadly this is the only piece I have found and I don't particularly want to smash it, but I will keep an eye out for more of them when I go to that same beach this evening. This site also says Whidbey Island is known to have jade, so next time you're there keep your eyes peeled!
http : // www . goldrushnuggets . com/rageandmiinw . html



IMG_20170803_135244.jpg
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 Viewed:  2308 Time(s)

IMG_20170803_135244.jpg



IMG_20170803_135404.jpg
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 Viewed:  2308 Time(s)

IMG_20170803_135404.jpg


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alfredo
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PostPosted: Aug 03, 2017 16:27    Post subject: Re: Is this jadeite or nephrite?  

I have kept my eyes open on Whidbey Island, but never saw a jade pebble. Several greenish epidote-bearing pebbles - Those might have been mistaken for jade by other rockhounds.
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PostPosted: Aug 03, 2017 18:29    Post subject: Re: Is this jadeite or nephrite?  

Jadeite pebbles shows white alteration skin. And they usually show green very rarely and in small spot inside a white mass.
In contrary nephrite presents big green masses.
If I had to choose only between 2 possibility, I would say nephrite for sure.
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PostPosted: Aug 05, 2017 00:37    Post subject: Re: Is this jadeite or nephrite?  

I have found pieces of Jade on the beach at Fort Casey. . . But always with the white rind. Jade is difficult to tumble, and the rock you have there looks pretty water tumbled.
All of the Jade I have found in Washington also has black specs in it.
As for specific gravity, while not precise, it's possible to get a rough idea using the suspension method, just be sure that the specimen touches no part of the container the water is in.



FB_IMG_1501911288823.jpg
 Description:
A piece of washington state jade
 Viewed:  1972 Time(s)

FB_IMG_1501911288823.jpg


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winn




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PostPosted: Aug 05, 2017 02:04    Post subject: Re: Is this jadeite or nephrite?  

Do you know if that location is producing jadeite, nephrite, or both? Marco said before that it's mostly jadeite that has the rind, though I must confess complete ignorance on the subject! Also, do you have any thoughts for what this might be with a specific gravity of ~3.0 if not nephrite jade?

I'm thinking I might try to saw off a sliver and saw it in half (I ordered a jeweler's saw and such), so I'll update in a couple days once I attempt to melt it, and with photos of it cut.
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PostPosted: Aug 05, 2017 03:06    Post subject: Re: Is this jadeite or nephrite?  

W4nder wrote:
...As for specific gravity, while not precise, it's possible to get a rough idea using the suspension method, just be sure that the specimen touches no part of the container the water is in.

You can use: DIY Specific Gravity Kit (tutorial) - (19)
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PostPosted: Aug 05, 2017 03:13    Post subject: Re: Is this jadeite or nephrite?  

FryI myself am quite new to this. It's my understanding that telling the 2 apart is difficult at best.
I've heard "jade" can come with all kinds of different rinds, but the only one I've ever been able to find is the white rind.
Learning about jade is difficult at best. People often seem very tight lipped about it. . . Sometimes getting information is like pulling teeth (please note here. . . I am referring to a different forum, not this one).
Many times I've gotten conflicting answers from different sources. . Such as "jade does not contain asbestos" and "the white rind almost always contains asbestos". And my personal favorite "yes, the rind is asbestos, but it's silicates so not dangerous". . . . What?
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