New Mineral Named After GIA’s John Koivula
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 Post subject: Asbestos in Petersite
PostPosted: Wed May 01, 2019 6:01 am 
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Hi,
I am currently working on a lovely blue and brown piece of Petersite .
Grinding it I have noticed it cracks easily.
If you pull the cracked piece away their are numerous fine hairs coming away from the broken area .
These fibres are bendable and resemble the fibres on raw Asbestos.
Any one else found this problem and I take it the Asbestos has not fully mineralized and I should not really be working on this material.
Any direction on this problem would be helpful. Thanks


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 Post subject: Re: Asbestos in Petersite
PostPosted: Wed May 01, 2019 10:49 pm 
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I can help you solve the problem. Just send the Pietersite to me and I'll dispose of it properly :D

Just kidding of course. I'll probably get flak from some others but I think concern about the asbestos "problem" with tiger's-eye and associated minerals is vastly overdone. Maybe if you were cutting it professionally over a long period there might be a problem. I've cut lots of it over many years with no discernible side effects.

I remember back when I first started casting jewelry. The old-time methods called for using moistened sheet asbestos wrapped inside flasks to supposedly prevent the investment from cracking when dried and exposed to heat from the burn-out oven. I used many sheets of asbestos for that purpose, serenely unaware that the tiny cristobalite particles that exploded into the air when quenching flasks were probably much more dangerous when inhaled than my minimal exposure to asbestos.

My rule is that if cutting any material makes you uncomfortable, don't cut it, or use appropriate means to minimize your exposure whether it's asbestos or some poison -- even radioactivity.

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 Post subject: Re: Asbestos in Petersite
PostPosted: Thu May 02, 2019 12:10 am 
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I would personally not handle any asbestos that isn't thoroughly silicified.

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 Post subject: Re: Asbestos in Petersite
PostPosted: Thu May 02, 2019 6:18 am 
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Rick thanks for the comments ,
I had done most of the work before coming across this problem and posting. Have just finished off the piece and took the opportunity to wash down splash guards and clean out and was tailing trays etc .
I have worked Petersite before, but it has been stable this material is quite different material and flaked easily and you could scratch up fibres on a chip with a finger nail ,although main surface is fine .
I will be wary of similar material in the future
Next problem will be letting the customer know, they will freak.


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 Post subject: Re: Asbestos in Petersite
PostPosted: Thu May 02, 2019 12:57 pm 
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I'm with ROM on this one.
I had a discussion of the asbestos sheets used for casting with Si Frazier years ago. (I may still have some).
He offered a long narrative on different types of asbestos and how the perils are exaggerated by folks who have not taken the time to study the nuances.


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 Post subject: Re: Asbestos in Petersite
PostPosted: Thu May 02, 2019 6:17 pm 
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This is not chrysotile as in those sheets, but crocidolite, the nastier kind. Some pietersite apparently occasionally has chunks of straight up friable unsilicified asbestos mixed in--someone posted a picture of the piece of fluff they'd pulled from a rough piece of chinese pietersite.
Even single exposures or low levels secondary expsoure to asbestos (as with the families of people who worked with asbestos, who also have increased risks).
It is difficult to get a really good assessment of the actual magnitude of the risk, since there are pressures in both directions on the risk assessment, both with plenty of money behind them. But there's no question that the risk from exposure is real. Normal tigereye might not give you any exposure, but this isn't what we're dealing with here--loose fluffy amphibole asbestos is just straight up nasty stuff and you'd do well to avoid it whenever possible.

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 Post subject: Re: Asbestos in Petersite
PostPosted: Fri May 03, 2019 5:14 am 
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After reading the two Mods comments I did a quick cast around for Petersite on internet sites.
In photographs of material for sale it all looked stable, I did not see any signs of fluffing of fibres in the photographs, but then the piece I was working on looked similar to those photographs. I fortunately have not worked enough of this material to comment further.
While looking around on internet sites I did come across this, which is worth casting an eye over for any cutters. https://www.gemsociety.org/article/gems ... ity-table/


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 Post subject: Re: Asbestos in Petersite
PostPosted: Fri May 03, 2019 10:15 pm 
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I've seen that chart come up before, though the lack of context and citations makes it much less useful than it could be.

By the way, here's a link to the terrifying pietersite hellfluff we had a few years back viewtopic.php?f=8&t=21182

This is what kids these days call a 'cursed image':
Image

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 Post subject: Re: Asbestos in Petersite
PostPosted: Sat May 04, 2019 12:14 pm 
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Oh, yuck.
Right Stephen. I wouldn't want to be inhaling that!


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