[MSA-talk] New mineral description needed

Anthony Kampf akampf at nhm.org
Tue Apr 26 13:59:38 EDT 2016


I checked the material by powder and single-crystal XRD. I can confirm that there is no match for the PXRD. Unfortunately, after numerous attempts at finding a suitable single crystal, I failed to get even a sensible unit cell. There is a lot of streaking of spots, indicating significant disorder in the structure. I suspect that there is also twinning on a very fine scale parallel to the plates.

Tony
______________________________________________
Anthony R. Kampf, Ph.D.
Curator Emeritus, Mineral Sciences
Natural History Museum of Los Angeles County
900 Exposition Blvd. , Los Angeles , CA 90007
Phone: 213-763-3328; Fax: 213-749-4107
Email: akampf at nhm.org<mailto:akampf at nhm.org>
______________________________________________


From: msa-talk-bounces at minlists.org [mailto:msa-talk-bounces at minlists.org] On Behalf Of Daniel Hummer
Sent: Tuesday, April 26, 2016 9:29 AM
To: msa-talk at minlists.org
Subject: Re: [MSA-talk] New mineral description needed

Henry,

I would be interested to know if anyone has tried single crystal measurements at a synchrotron beamline. How thin are the samples? With the high intensity of a synchrotron source and adequate data collection time, even samples of 10 microns or less could potentially yield good enough single crystal data to solve the structure, especially with the presence of a moderate Z element like Fe. I'm sure there are a number of people on the list who could help if synchrotron XRD hasn't been tried yet.

Best,
Dan Hummer



Daniel R Hummer

Postdoctoral Scholar, Mineralogy and Crystallography

Geophysical Laboratory

Carnegie Institution for Science

dhummer at ciw.edu<mailto:dhummer at ciw.edu>

Office: 202-478-8908

Cell: 814-321-8859

Fax: 202-478-8901
On 4/26/16 12:19 PM, Henry Barwood wrote:
There is a new hydrated iron phosphate mineral found at Girard, Burke County, Georgia that needs analysis and description. It was recognized (by me) as a new mineral 22 years ago and has been looked at by 4 separate groups without success. The problem is that the crystals, while well defined are simply too thin to yield adequate single crystal data for crystal structure analysis. Does anyone on the list have access to electron diffraction or another technique that might be able to solve this mineral? I would really like to see it described since it would represent the first mineral with a Georgia type locality. I have very few specimens of this left but would sacrifice 1-2 if anyone believes they have a reasonable possibility of success. Thanks.

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