[sdpd] Unknown zeolite !

[Armel Le Bail <alb...@cristal.org>]

Hello,

In the long series of powder diffraction problems there
is a challenging one. Because the mineral in question is
a zeolite, I am sure that a lot of people would be interested
in solving its structure. Everybody can find it in most zeolite
review papers. Of course it has not been attributed a
framework code, since the framework is unknown. The name
is cowlesite, Ca6[Al12Si18O60].33H2O. JCPDS-ICDD 29-0286
and 46-1405. Micromounts of samples can be afforded for 3 US$.
A search in Google gives a lot about it.

Well, if you have a good synchrotron powder pattern, or even a
good conventional X-ray powder pattern, I would be curious to see it.
You may organize an interesting Round Robin. Solving the cowlesite
crystal structure is clearly a challenge for any SDPD package,
including those which "help you to solve crystal structure faster".

Best,

Armel

PS- 1 : SDPD thought of the day which may apply to cowlesite:
"A proposed cell without a crystal structure is highly dubious,
even if the cell comes from 'single crystal' data".

PS- 2 : The SDPD Mailing list will be unattainable from March 15,
evening to March 18, because of YahooGroups maintaining.



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