Sunday, July 04, 2010

More on the asbestos dust-up

Silver Fox has an excellent summary of serpentine group minerals, serpentinite rock, and the various asbestiform minerals. An even more interesting discussion has taken place on the pages of Elements magazine, the joint membership / review journal of a number of mineralogical and geochemical societies.

In June 2009, Micky Gunter wrote a scathing article on how mineralogists were being left out of the asbestos debate. This was complimented by an outreach article by Thomas Feininger on the use of Mg3Si2O5(OH)4 as the launching pad for all sorts of cool interdisciplinary and instructional mineralogy.

Four months later, Gregory Meeker of the USGS chimed in on the dark side of mineralogists in the asbestos debate, and Micky Gunter replied. The following part of Meeker’s article is worth quoting:

Gunter takes exception to a recent legal definition of asbestos; but there is more to that story. For over 70 years, the fibrous amphibole that is a major—not trace—constituent in the Vermiculite Mountain vermiculite deposit near Libby, Montana, was called tremolite, sodium-rich tremolite, or sodic tremolite by everyone including the mineralogists and geologists who studied the deposit. During the 1970s, the names of the regulated asbestos minerals, including tremolite asbestos, were entered into the U.S. Code of Federal Regulations. As recent court proceedings have revealed, company geologists, owners, and operators of the vermiculite mine near Libby understood that the asbestiform amphiboles in the mine fell under those regulations. In 1978 and 1997, committees of the International Mineralogical Association published new recommendations for amphibole nomenclature. Based on this new system of nomenclature, most of the amphibole minerals at the Libby mine were reclassified as winchite. When public and regulatory attention returned to Libby in 1999, mineralogists working on behalf of the company that owned the mine used the changes in nomenclature to claim that the majority of the Libby amphibole had been mistakenly identified as tremolite and therefore was not regulated. A federal judge sided with the defense and, based on a 2003 USGS study of the minerals, ruled that only 6 percent of the Libby asbestos was regulated.

In short, the mining company mineralogists and lawyers knew perfectly well that their waste was just as deadly as ever, but they used a name change as a loophole to avoid culpability.

I originally came across this story with the intention of using it of an example of why nomenclature and other definition committees should not be too high-minded and ivory tower- in this case, the amphibole reclassification let the bad guys get away with murder. And this brings us to the comment section of the California bill:

Chrysotile serpentine, also known as white asbestos, is the most common form of asbestos. Mg3(Si2O5)(OH)4.

Putting the idealized serpentine group formula in a sentence all by itself is extremely nebulous, but one way of reading this is that they are trying to define asbestos as Mg3(Si2O5)(OH)4. This would, of course, exclude the dangerous asbestiform amphiboles (e.g. Na2(Fe,Mg)5Si8O22(OH)2, or crocidolite) from the definition. This strikes me as asking for trouble.

Further reading:

Ann G. Wylie and Jennifer R. Verkouteren; Amphibole asbestos from Libby, Montana: Aspects of nomenclature; American Mineralogist; October 2000; v. 85; no. 10; p. 1540-1542

The Composition and Morphology of Amphiboles from the Rainy Creek Complex, Near Libby, Montana; G.P. Meeker, A.M. Bern, I.K. Brownfield, H.A. Lowers, S.J. Sutley, T.M. Hoefen and J.S. Vance; American Mineralogist; November-December 2003; v. 88; no. 11-12; p. 1955-1969

Mickey E. Gunter, M. Darby Dyar, Brendan Twamley, Franklin F. Foit, Jr. and Scott Cornelius; Composition, Fe3+/{sum}Fe, and crystal structure of non-asbestiform and asbestiform amphiboles from Libby, Montana, U.S.A.; American Mineralogist; November-December 2003; v. 88; no. 11-12; p. 1970-1978.

Mickey E. Gunter, Karen E. Harris, Kristin L. Bunker, Rebecca K. Wyss and Richard J. Lee; Amphiboles between the sheets: observations of interesting morphologies by TEM and FESEM; European Journal of Mineralogy; December 2008; v. 20; no. 6; p. 1035-1041; DOI: 10.1127/0935-1221/2008/0020-1872

Mickey E. Gunter, and Matthew S. Sanchez; Amphibole forensics: Using the composition of amphiboles to determine their source, the Libby, Montana, example; American Mineralogist; May-June 2009; v. 94; no. 5-6; p. 837-840; DOI: 10.2138/am.2009.3224


Silver Fox said...

They (EPA, anybody writing rules, regs, and legislation...) really need to talk to mineralogists, as you pointed out. Keeping track of amphiboles (and other minerals) requires an expert.

Mindat has only 10 photos of winchite, unfortunately none are the asbestiform or acicular version. It does list winchite and tremolite at Libby, MT, and has actinolite crossed out.

Do you suppose the winchite at Libby was particularly Na-rich for it's widely ranging possible chemical formula and that's why they thought it was tremolite? Because of the way amphibole formulas work, the winchite chemistry could be identicle or nearly identicle to tremolite: [Ca2][Mg5][(OH)2][SiO22].

(I like your post title much better than mine. I put mine in as a placeholder, then forgot to think about a better title before hitting post.)

Chuck said...

SF, as far as I can tell, the Libby amphibole was described as sodic tremolite because either the term winchite was not in widespread use, or it had not been formally defined. You'd have to go through the nomelclature reports to get the details, but the timeline I get is this:
1960's-1970's: Asbestiform amphibile is described as sodic tremolite, health concerns become apparent.
1970's: EPA codifies asbestiform tremolite as a hazardous material
1980's nomelclature committee reclassifies sodic tremolite as winchite.
1980's: nomenclatural changes cause dangerous tremolites to be reclassified as winchite. Winchine not listed by EPA, as they've never heard of it.
2000's: COmapany says that the winchite formalrly known as tremolite is safe, since Winchite isn't regulated.

I'll update with some literature links as time permits