American Mineralogist, 2004, V 89, N 2-3, February-March.

LETTERS

455 
A new dense silica polymorph: A possible link between
tetrahedrallyand octahedrally coordinated silica 
Sheng-Nian Luo, Oliver Tschauner, Paul D. Asimow,
and Thomas J. Ahrens 

462 
Epitaxial relationships of clinopyroxene-hosted magnetite
determined using electron backscatter diffraction
(EBSD) technique 
Joshua M. Feinberg, Hans-Rudolf Wenk, Paul R. Renne,
and Gary R. Scott 

ARTICLES 

257 
Composition and I4/m-P42/n phase transition in
scapolite solid solutions 
Yusuke Seto, Norimasa Shimobayashi, Akira Miyake,
and Masao Kitamura 

266 
Synthesis and characterization of K2Ca5(SO4)6•H2O,
the equivalent of gorgeyite, a rare evaporite mineral 
J. Theo Kloprogge, Liesel Hickey, Loc V. Duong,
Wayde N. Martens, and Ray L. Frost 

273 
Phase relations in the system Fe-FeSi at 21 GPa 
Yasuhiro Kuwayama and Kei Hirose 

285 
Nucleation and growth kinetics of the a-b transformation
in Mg2SiO4 determined by in situ synchrotron
powder X-ray diffraction 
Tomoaki Kubo, Eiji Ohtani, and Ken-ichi Funakoshi 

294 
Experimental determination of siderite stability and
application to Martian Meteorite ALH84001 
Andrea M. Koziol 

301 
Determination of the molar absorption coefficient for
the infrared absorption band of CO2 in rhyolitic glasses 
Harald Behrens, Nathalie Tamic, and Francois Holtz 

307 
Crystallographic properties of the calcium phosphate mineral,
brushite, by means of First Principles calculations 
C. Ignacio Sainz-Diaz, Ana Villacampa, and Fermin Otalora 

314 
The crystal structure of jonesite, 
Ba2(K,Na)[Ti2(Si5Al)O18(H2O)](H2O)n: A first example of
titanosilicate with porous double layers 
Sergey V. Krivovichev and Thomas Armbruster 

319 
Crystal-chemistry of talc: A near infrared (NIR)
 spectroscopy study 
Sabine Petit, Francois Martin, Andrzej Wiewiora,
Philippe De Parseval, and Alain Decarreau 

327 
Synthesis of beryllian sapphirine in the system
MgO-BeO-Al2O3-SiO2-H2O and comparison with
naturally occurring beryllian sapphirine and
khmaralite, Part 2: A chemographic study
of Be content as a function of P, T, assemblage
and FeMg-1 exchange 
A. G. Christy and E. S. Grew 

339 
Spriggite, Pb3[(UO2)6O8(OH)2](H2O)3, a new mineral
with b-U3O8-type sheets: Description and
crystal structure 
Joel Brugger, Sergey V. Krivovichev, Peter Berlepsch,
Nicolas Meisser, Stefan Ansermet, and Thomas Armbruster 

348 
Sieve-textured plagioclase in dacitic magma: 
Interference imaging results 
Martin L. Stewart and Thomas H. Pearce 

352 
Single crystal raman spectroscopy of cerussite 
Wayde N. Martens, Llew Rintoul, J. Theo Kloprogge,
and Ray L. Frost 

359 
Sodalite: high-temperature structures obtained from
synchrotron radiation and Rietveld refinements 
Ishmael Hassan, Sytle M. Antao, and John B. Parise 

365 
The structure of metahohmannite, Fe23+[O(SO4)2]•H2O,
by in situ synchrotron powder diffraction 
Fernando Scordari, Gennaro Ventruti, and 
Alessandro F. Gualtieri 

371 
High-pressure synchrotron X-ray diffraction study of 
spessartine and uvarovite: A comparison between different
equation of state models 
Valeria Diella, Alessandra Sani, Davide Levy, and Alessandro Pavese 

377 
Quantum calculations of the electronic structure and NMR
 quadrupolar interaction parameters for tugtupite 
Bing Zhou and Barbara L. Sherriff 

382 
Identification of pyrite valence band contributions using
synchrotron-excited X-ray photoelectron spectroscopy 
H.W. Nesbitt, A.G. Berlich, S.L. Harmer, I. Uhlig,
G.M. Bancroft, and R. Szargan 

390 
Micro-Raman studies of gypsum in the temperature range
between 9 K and 373 K 
Chi Hong Chio, Shiv K. Sharma, and David W. Muenow 

396 
A new rare earth disilicate (REE2Si2O7; REE = Dy, Tm, Lu; type-L):
Evidence for nonquenchable 10 GPa polymorph with silicon
in fivefold trigonal bipyramidal coordination? 
Michael E. Fleet and Xiaoyang Liu 

405 
Structural variations in the brownmillerite series 
Ca2(Fe2-xAlx)O5: Single-crystal X-ray diffraction 
at 25 °C and high-temperature X-ray powder diffraction
(25 °C ? T ? 1000 °C) 
Gunther J. Redhammer, Gerold Tippelt, Georg Roth,
and Georg Amthauer 

421 
Peculiarity and defect structure of the natural and synthetic
zeolite mordenite: A single-crystal X-ray study 
Petra Simoncic and Thomas Armbruster 

432 
Model independent phase equilibrium constraints on the
ferrosilite activity in the binary Fe-Mg orthopyroxene
solid solution 
Leonid Y. Aranovich 

439 
Microstructural study of synthetic sintered diamond
and comparison with carbonado, a natural
polycrystalline diamond 
Subarnarekha De, Peter J. Heaney, Yingwei Fei,
and Edward P. Vicenzi 

447 
Structural and chemical response to varying [4]B content
in zoned Fe-bearing olenite from Koralpe, Austria 
John M. Hughes, Andreas Ertl, M. Darby Dyar, Edward S. Grew,
Michael Wiedenbeck, and Franz Brandstätter 

467 
NEW MINERAL NAMES 
John L. Jambor, and Andrew C. Roberts 

472 
BOOK REVIEW 
Leonid V. Bershov 
LUMINESCENT SPECTRA OF MINERALS: REFERENCE-BOOK.
by Boris S. Gorobets and Alexandre A. Rogojine.
All-Russia Institute of Mineral Resources (VIMS).
Moscow, 2002. 300 pp.