[Rockhounds] What is a mineral (GSA)

[Kreigh Tomaszewski]

Don,

Fifteen minutes of fame at a GSA conference may not be a big deal for
you, but I think it is a significant accomplishment and applaud you.

Your note, and the abstract, make me want to read the whole paper. How
does one get a copy of it? 

Kreigh





DonH wrote:
> 
> John Siebel wrote:
> 
> > Brother Don,
> >
> > You're addressing the GSA? Do tell!
> 
> Oh, it was no big thing--a submitted talk on the use, and misuse, of EDS
> in forensics.  Here is the abstract:
> 
> http://gsa.confex.com/gsa/2007AM/finalprogram/abstract_129180.htm
> 
> It was neat because I was able to include a real-life situation where a
> collector from the Franklin NJ area sent out a sample to be identified
> using EDS (energy dispersive spectroscopy, an analytical system usually
> combined with an SEM).  The "closest match" was for svabite, a rare
> apatite that is in the same series as the ones known from that locality
>   but has never been identified from the Franklin/Sterling Hill
> district.  Using samples provided to me, I was able to demonstrate that
> EDS cannot identify these apatites with certainty.  In fact, I used a
> more accurate and precise instrument, the electron microprobe, and I'm
> still not certain.  The problem lies in the fact that there is a halogen
> site which contains one atom of either (F,Cl,OH), and possibly others,
> per formula unit.  The identity of the species is dependent upon one of
> these being >50% of the total of two others, and at such low quantities,
> the precision becomes a problem.  The bigger issue is that neither of
> these instruments can detect H, so with the probe, (OH) is calculated by
> difference.
> 
> I also did a segment on how you can't really tell gypsum and anhydrite
> apart using EDS, but you can with x-ray diffraction, and how this would
> be useful for people trying to determine whether residual dusts from New
> York city came from the World Trade Center incident (gypsum in wallboard
> becomes anhydrite when heated in a fire).
> 
> So anyway I was told it went very well.  Several crime lab and FBI folks
> seemed happy with my work so far, which suggests it is on the right track.
> 
> best,
> Don
>