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Fwd: Crystallographic data for Cranswickite

  • To: Discussion list of the IUCr Commission on Crystallographic Computing <compcomm@iucr.org>
  • Subject: Fwd: Crystallographic data for Cranswickite
  • From: harry powell <harry@mrc-lmb.cam.ac.uk>
  • Date: Thu, 15 Jul 2010 08:48:17 +0100
  • References: <B44FC7D084A91B43A65174854E70E8B786D196AF09@EXMBX01.ad.oak.ox.ac.uk>
Dear all
FYI
Begin forwarded message:
> From: Amber Thompson <amber.thompson@chem.ox.ac.uk>> Date: 14 July 2010 23:36:58 BDT> Subject: FW: Crystallographic data for Cranswickite>>> For info.>> A.>> ________________________________________> From: Ron Peterson [peterson@geol.queensu.ca]> Sent: 14 July 2010 20:09> To: Rietveld_l@ill.fr> Subject: Crystallographic data for Cranswickite>> It is my honour to inform everyone that the International  > Mineralogical Association has recognized a new mineral species and  > approved that it be named "cranswickite".>> The new mineral is named in honor of Lachlan M. D. Cranswick  > (1968-2010) who, as a crystallographer and mineralogist at the NRC  > Canadian Neutron Beam Centre located at Chalk River Laboratories,  > specialized in applying neutron beams to the studies of materials  > science, structural chemistry, magnetism and geology.  He assisted  > many scientists and students from universities across Canada to  > apply these scientific tools to advance their research programs.   > Lachlan Cranswick was passionate about ensuring the highest quality  > facilities for those scientists.>> Lachlan also made a significant contribution to the application of  > powder diffraction techniques by helping to develop and maintain  > the Collaborative Computational Project No. 14 in Powder and Small  > Molecule Single Crystal Diffraction (CCP14) (Cranswick 2008).>> Below is the abstract of the manuscript that will be submitted  to  > the American Mineralogist for publication>> Abstract> Cranswickite is a new mineral of composition MgSO4 •4(H2O) from  > Calingasta, Argentina (IMA2010-016).  Cranswickite is monoclinic,  > space group Cc, a = 11.9183(3)Å, b= 5.1709(1)Å, c = 12.1888(3)Å,  > β = 117.537°(2), V=  666.1 Å3, Z =4. The mineral occurs as a soft  > white vein filling in a metasedimentary rock (dcalc =1.918 Å3 ).The  > atomic structure has been determined by direct methods and refined  > by Rietveld refinement of powder diffraction data. The atomic  > structure consists of chains of corner-sharing magnesium-containing  > octahedra and sulfate tetrahedra. All the water molecules directly  > coordinate magnesium in the structure. The five strongest lines in  > the powder X-ray diffraction data are [dobs  in Å (I)(hkl)]: 5.259  > (100) (200), 3.927 (46) (1 1 -2), 3.168 (45) (1 1 -3), 4.603 (29)  > (1 1 -1), 2.570 (23) (3 1 1). Infra-red and Raman spectra are very  > similar to the spectra measured from starkeyite.  Cranswickite is  > closely related to starkeyite MgSO4•4(H2O) that has an atomic  > structure where two sulfate tetrahedra and two magnesium octahedra  > share corners to form a four-membered ring and not a chain as in  > cranswickite.>> --> Professor R.C.Peterson> Chairman of Undergraduate Studies in Arts and Science> Department of Geological Sciences and Geological Engineering,> Queen's University, Kingston, Ontario, Canada> 613-533-6180        fax 613-533-6592>
Harry--Dr Harry Powell,MRC Laboratory of Molecular Biology,Hills Road,Cambridge,CB2 0QH



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