 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Natural Science Forum / Earth Science / Mineralogy / June 2008microstructure of nephrite, and dust hazards
I believe nephrite (New Zealand greenstone, pounamu) has a microscopically fibrous structure. What happens when you grind it to dust? I have a small piece I'd like to work into a pendant. If it breaks up into fibres with the same sort of hazard potential as blue asbestos I'd have to rethink. Anybody know for sure? ==== j a c k at c a m p i n . m e . u k === <http://www.campin.me.uk> ==== Jack Campin, 11 Third St, Newtongrange EH22 4PU, Scotland == mob 07800 739 557 CD-ROMs and free stuff: Scottish music, food intolerance, and Mac logic fonts > I believe nephrite (New Zealand greenstone, pounamu) has a > microscopically fibrous structure. [quoted text clipped - 11 lines] > EH22 4PU, Scotland == mob 07800 739 557 CD-ROMs and free stuff: > Scottish music, food intolerance, and Mac logic fonts Hi Jack: I can find no specific information on that material but I did a quick web search and found nothing that suggested that it was anymore hazardous than any other hard rock. But grinding any rock can cause hazardous dust. Always grid rocks with a wet grinding medium and wear a dust mask. It is never safe to polish any rock with out taking precautions. This is a must no mater what kind or rock your working. John Passaneau On Jun 16, 9:59 pm, Jack Campin - bogus address <bo...@purr.demon.co.uk> wrote: > I believe nephrite (New Zealand greenstone, pounamu) has a microscopically > fibrous structure. [quoted text clipped - 10 lines] > Jack Campin, 11 Third St, Newtongrange EH22 4PU, Scotland == mob 07800 739 557 > CD-ROMs and free stuff: Scottish music, food intolerance, and Mac logic fonts Nephrite is fibrous actinolite and therefore is a form of amphibole- asbestos. Therefore, be aware of the potential health hazards. Use a search engine and look for: actinolite health hazard and you can read up on it. George > On Jun 16, 9:59 pm, Jack Campin - bogus address > <bo...@purr.demon.co.uk> wrote: [quoted text clipped - 19 lines] > > George On the other hand, if you are making a single piece of jewelry or a carving, and wear a dust mask when wet cutting, I think the risk is probably miniscule. With the mask, you likely get less junk in your lungs than when I dust the house, or it is a bad air quality day outside, or a person enters a smoky pizza joint or bar. Don't know what your intent is, but if it is nephrite which is microcrystalline enough to withstand cutting and take a high polish, it likely won't separate into fibers. At the height of the US asbestos scare in the early 1980s, people were pulling tigereye jewelry from sale because of its alleged hazard. That seemed a little like overkill to me. >>> I have a small piece [of nephrite] I'd like to work into a pendant. >>> If it breaks up into fibres with the same sort of hazard potential [quoted text clipped - 6 lines] > lungs than when I dust the house, or it is a bad air quality day > outside, or a person enters a smoky pizza joint or bar. Asbestos fibres have a different level of risk. Other kinds of mineral dust may cause obstructive disease when you breathe enough; with asbestos, the carcinogenic effect operates at much lower doses. There is no safe level of exposure. > Don't know what your intent is, but if it is nephrite which is > microcrystalline enough to withstand cutting and take a high polish, > it likely won't separate into fibers. I was going to use a motorized grinding wheel to rough out the shape. That certainly would produce fibres, if they're there to be produced. > At the height of the US asbestos > scare in the early 1980s, people were pulling tigereye jewelry from sale > because of its alleged hazard. That seemed a little like overkill to me. Yes, like scrapping uranium-glazed pottery. Fibres are hardly going to leap out of a polished stone and down your lungs. It would be interesting to know what happens to workers in Chinese jade trinket factories. (I presume jade has the same sort of problem). Nothing good, I'd bet. ==== j a c k at c a m p i n . m e . u k === <http://www.campin.me.uk> ==== Jack Campin, 11 Third St, Newtongrange EH22 4PU, Scotland == mob 07800 739 557 CD-ROMs and free stuff: Scottish music, food intolerance, and Mac logic fonts >>>> I have a small piece [of nephrite] I'd like to work into a pendant. >>>> If it breaks up into fibres with the same sort of hazard potential [quoted text clipped - 11 lines] > with asbestos, the carcinogenic effect operates at much lower doses. > There is no safe level of exposure. Um...my grandfather was a carpenter who died of asbestos-related lung cancer. He was out there for years, with no mask, blowing insulation in to buildings in the 1940s and 50s. I know more about asbestos than I care to, already. He lived to 75, though the end wasn't pretty. I also live in a town with a silica plant-- the first place in the US to sue for damages due to silicosis "white lung". I cave, where I am exposed to elevated levels of radon, and all sorts of risks underground. But I cave for a couple of hours a month-- it isn't like a 40 hour employment exposure, or having a 'hot' basement. I don't buy the "there is no safe level of exposure". We live on a planet filled with toxic substances,and there is no way we can avoid exposure to them. We can do a really good job of lessening exposure, but there is no happy world where no toxic exposures exist. The decision to accept or not accept the risk is yours, of course. I still don't think creating one piece of jewelry using appropriate protection is more hazardous to one's health than driving in traffic. (My standard of risk.) Best wishes, Jo Schaper Jo Schaper a écrit dans le message ... >>>>> I have a small piece [of nephrite] I'd like to work into a pendant. >>>>> If it breaks up into fibres with the same sort of hazard potential [quoted text clipped - 34 lines] >Best wishes, > Jo Schaper Jo Schaper is right in geneal about risks. However nephrite is far from fibrous. It is very compact and makes ups along with jadeite what is called jade. Many years ago I found some nephrite along North Clear Creek canyon in Colorado next to what is now the water treatment plant. A local artist made some fine jewelry out of it. The rock in which it was found was not local but dumped there by a road crew. I was never able to find out it's origins. Anyone going up to Blackhawk to gamble may want to check out some of the rocks along the road next to the treatment plant. JL |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.