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Given that it is difficult to determine who is telling the truth in the recent claim that J&J covered up finding asbestos in their powder, is there any chemical test that we can perform on our own to determine with reasonable confidence whether the particular sample of powder we have bought contains asbestos? (I am aware that one test involves viewing the sample under a sufficiently high-powered polarizing light microscope, but not everyone has such a tool.)

I have not much chemistry background beyond high-school, and it seems that there are numerous kinds of asbestos, apparently characterized more by their large aspect ratio than by their chemical composition. For example, chrysotile (which accounts for ≈95% of asbestos in buildings in the US) has an idealized chemical formula $\ce{Mg3(Si2O5)(OH)4}$, but may not even occur as exactly that. Talc according to wikipedia is either $\ce{H2Mg3(SiO3)4}$ or $\ce{Mg3Si4O10(OH)2}$. These break down as follows:

Chrysotile: $\ce{(Mg^2+)3[Si2O5]^2−([OH]^−)4}$

Talc A: $\ce{(H+)2(Mg^2+)3([SiO3]^2+)4}$

Talc B: $\ce{(Mg^2+)3[Si4O10]^4−([OH]^−)2}$

So we cannot test for $\ce{Mg^2+}$ or $\ce{[OH]^−}$. But is there a chemical test for $\ce{[Si2O5]^2−}$ that can be done at home? And is it safe to rule out chrysotile if no $\ce{[Si2O5]^2−}$ can be detected, or can the amount be too low for chemical detection but still dangerous?

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    $\begingroup$ There isn't a "home test." $\endgroup$ – MaxW Dec 31 '18 at 18:12
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    $\begingroup$ The chemical difference between asbestos and talc is very small: the differences are structural. This is why the best test is probably to look at a sample with a microscope. $\endgroup$ – matt_black Dec 31 '18 at 20:29
  • $\begingroup$ If you have an X-ray diffractometer in your garage, that would be best to test for asbestos. $\endgroup$ – A.K. Jan 1 at 6:50
  • $\begingroup$ @matt_black: Thanks, but I'm not sure I understand your comment. Are you saying that talc has Si2O5 as well? Or are you saying that Si2O5 has very similar chemical properties to Si4O10? Or something else? $\endgroup$ – user21820 Jan 1 at 9:07
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    $\begingroup$ @user21820 Very different minerals result from small changes to the structure of the silicate units they contain. The differences are caused by the subtly different way the SiO2 units are connected. Those differences are not easy to detect chemically. So, yes, Si2O5 is hard to tell apart from Si4O10 using chemistry (but trivially easy looking at the crystals of the mineral). $\endgroup$ – matt_black Jan 1 at 11:32

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