Stephen,
Apart from your own XRF data (Ball et al, RCM 1996, 10; 987) you find 
NBS19 chemical composition data for instance in Ghosh et al, RCM 2005, 
19; 1097 on page 1101. Using ICP-MS and ICP-OES we found 98.1% CaCO3 and 
1.8% MgCO3. Non-carbonate traces (Al, Fe, Cu, Mn, Na, and K) were 0.08% 
in total.
Regards   Willi

Crowley, Stephen wrote:
> Dear ISOGEOCHEMISTS,
>
> Could I ask if anyone knows whether the mineralogy of NBS18 and NBS19 has been confirmed and whether the chemical composition of these standards has ever been reported? I'd be grateful for any information on possible data sources.
>
> Regards,
>
> Steve Crowley
>
> Department of Earth & Ocean Sciences
> University of Liverpool
> 4 Brownlow Street
> Liverpool
> L69 3GP
> UK
>
> 0151 794 5163/5164
>
>
>   

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Willi A. Brand, Stable Isotope Laboratory      [log in to unmask]
Max-Planck-Institute for Biogeochemistry (Beutenberg Campus)
Hans-Knoell-Str. 10, 07745 Jena, Germany      Tel: +49-3641-576400
P.O.Box 100164,      07701 Jena, Germany      Fax: +49-3641-577400
http://www.bgc-jena.mpg.de/
http://www.bgc-jena.mpg.de/service/iso_gas_lab/
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