amphibole alters to asbestos minerals?

Dear friends

in the La Higuera mine district (Coquimbo province, Chile), lately there is an increase of the lung cancer among miners.
Recently Asbestos stuff in the smelter processed material, have been reported from local authorities.

Actually, no visible asbestos mineral have been confirmed yet by analysis or field work; skarn host rock is predominant in most the old and active minesites; and the paregenesis of such mines, are:

amphybole, pyroxene, pyrite, chalcopyrite and magnetite species.

My question are:

a. most of the dumps have been exposed to atmospheric agents since 1890;
thus, are there any "hidrolisis" or meteoric process that may alters amphybole (or pyroxene) to somewhat similar to asbestos stuff?

b. Amphibole material is dangerous or may alters to poisonous compounds during Cu smelter process?

c. Are there any relation with this smelter material, and the wheathering decomposition of the amphybole minerals mined there?

Two of my chilean coleagues asked me to gather as much cientific and didactic info as possible

thanks in advance for your help

Maurizio Dini
La Serena - Chile

There are a number of amphibole minerals that have asbestoform varieties, which are known to cause health problems due to inhalation. Unfortunately, lung cancer is not specific to asbestos exposure. There are many other inhaled or ingested irritants that can be the cause, smoking tobacco being far and wide the most prevalent. If mesothelioma is detected, then one can draw a pretty certain coorelation to asbestos exposure.

Hello Jesse

many thanks for your statement.

One thing; can you please mention which are exactly those "number of amphibole minerals that have asbestoform varieties"....?

Our university will start some x-ray analysis, and it will be usefull to know specific species, that may match with our results!

thanka again
Maurizio D.

[pubs.usgs.gov]

[www.epa.gov]

Maurizio,

I do not think that x-ray diffraction can distinguish between asbestiform and non-asbestiform varieties of the amphibloles (such as amosite vs. grunerite and crocidolite vs. reibeckite), as the difference is purely morphological. Here in the US, the standard analytical technique for identifying asbestiform amphiboles is either polarized light microscope (for soil, rock or building materials) or transmission electron microcope with EDS (for airborn or waterborn particulate).

Thanks Jesse. 10 years ago I saw a national health ministries analyses of fibers from a building where employees suspected asbestos fibers to be present. The ministry stated: According to the chemical composition..... (which indeed showed one of the main minerals which can be asbestiform, i.e. very fine fibers) it is no asbestos.... My dear.

Maurizio,

'Asbestos' is defined differently when you discuss health and mineralogy. In mineralogy 'asbestos' means long fibres and indeed amphiboles, pyroxenes and serpetines may form asbestos.
There are formal definitions of 'asbestos' in health and the definitions differ but tend to be something along a) mineral origin, b) between maximum & minimum length, and c) with a the length/width ratio within a certain range. b) always leaves you with small particles, which may be airborne. c) leaves you with something slender. Basically, long fibres don't fly and you can't breathe them - they are harmless.
The problem with asbestos sensu health is:
1) it is airborne and you may breathe it in, even if not immediately exposed.
2) 'small' size and 'slender' means it may get stuck in your lungs. Stuck as in stuck in cells/cell membranes and too small for mucus/fibrils to expel them.
3) 'mineral' means indestructible. Your body will continuosly produce antibodies against the fibres, having no effect on the fibre but potentially harming the tissue.

You mention amphiboles & the smelter. Before sending ore into the smelter, it is crushed. Crushing amphibole may produce dust corresponding to the health asbestos definition.
If you want to demonstrate the presence of asbestos in the air, which is likely the only place it may be a hazard, you should collect air samples in relevant sites and analyse the dust by optical microscopy - any old mineralogist will be delighted to show you how. That will allow you to identify fibre size, mineralogy and abundance in pretty much the same operation.

Note that moderate asbestos fibres in the air may be a substantial hazard in combination with smoking tobacco. I once saw an analysis of car mechanics' health in Denmark. This was from when asbestos was used in brakes and protection/exhaust was not in use. Pretty much every smoke working with brakes died within 10 years, non-smokers did not.

All the best

Claus

____________________________________________________________________________
Claus Hedegaard
[www.Natureshop.dk]
[www.Hedegaard.com]
Strandvejen 2a, 8410 Rønde, Denmark

Dear David, Peter, Jesse and Claus

I am really greatfull for all your contributions, very clear and truly reasonable, in terms of how shall we focus the work.

Thus, one varialble is collecting Air samples !

I will show this thread to personnel and professors hear in our University, and will be more then willing to share what we have find out (chilean organization team and schedule are quite different from other countries...), when they may be available.

thanks again

Maurizio D.

Hello Claus, Maurizio,

As you mention, airborne mineral fibers are the real issue when it comes to health risks, as these are the ones that can be inhaled. It is the small fibers (<5um) that penetrate and become lodged in the deep lung and are thus the most hazardous. Unfortunately, one can not generally identify these by optical means. A 5 micron long fiber will have a sub-micron diameter, making it difficult, if not impossible to determine it's optical characteristics. This is why TEM/EDS is used to identify asbestos fibers collected in air samples. The combination of morphology, electron diffraction and major-element chemistry by EDS is how the identification is made. I spent a good number of years of my "professional" life doing just this. If you need info on the proceedures for collecting and analyzing air samples (or soil, crushed rock, etc.) let me know. I may still have copies of the "official" US EPA and NIOSH methods somewhere in the files.

Cheers,
Jesse

I was catching up on my reading material and read Elements 3(6) from December 2007 [yes, I am about six months behind!]. It is an issue on 'Medical Mineralogy and Geochemistry'.
It contains an interesting review article by Fubini & Fenoglio, "Toxic potential of mineral dusts" (pp. 407-414), dealing with asbestos and its effect.

Claus

____________________________________________________________________________
Claus Hedegaard
[www.Natureshop.dk]
[www.Hedegaard.com]
Strandvejen 2a, 8410 Rønde, Denmark