Hi Mohammed, are you talking about both natural and anthropogenic glasses? Personally, I'd look for (1) low totals in element composition - glasses usually tend to 'soak up' water and are prone to alteration; such glasses may also show perlitic fractures (e.g., the hydrated natural Dellen impact glass still shows a beautiful perlitic pattern after 140 million years, see Mark et al., 2013 in press); (2) look for spherulitic textures, sheaf-like microcrystalline mineral aggregates that show radiating extinction, which might be better done using an optical polarization microscope; a good reference is the article by Gary Lofgren (1971); (3) you might detect local domains where the glass has been replaced by clay minerals or other alteration products. I guess there is plenty of literature about this. I'm not so sure whether you can acquire real 'structural' data in the strict sense with a common SEM unless you maybe use TEM or EBSD. Good luck.

Dear Martin,

Thank you so much for your detailed comment. In fact, the glass samples in question are totally synthetic, and as I mentioned above, they 're characterized by their low resistance against devitrification. Thus, having this particular behavior, do you think that glass samples could provide worthwhile informations about glass structure by using imaging techniques (SEM, TEM...)?

Hi Mohammed

When you talk of resistance against devitrification it can be on cooling (from the melt for example) or on heating from the glass.

If you already obtained a glass, you can plan thermal treatments (Temperature, time) and after that, analyze the a)surface and b)cross sections of yor crystallized samples by SEM.

But if crystals are lager than a few microns you can also use optical microscopy. If you have an EDS analyzer with your SEM you can determine aproximate composition of your crystaline phases.

Also crystal morphology can give information of how many crystalline phases you have.

Generally you need a slight chemical attack to reveal your crystals.

Eventualy you will be able to determine the crystal nuceation and growth rates.

In glasses very prone to devitrify (no controlled crystallization) perhaps you are not able to obtain information using microscopy, in that case DTA (thermal analysis) can be usefull.

TEM can be usefull but it is harder to use (sample preparation and image analyses).

For more information refer to Zanotto E.D. and Vladimir Fokin papers for example.

Good luck!

Thank you very much Dr Prado for your detailed and helpful response!