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Sazhinite-(La), Na3LaSi6O15(H2O)2, a new mineral from the Aris phonolite, Namibia: Description and crystal structure

Published online by Cambridge University Press:  05 July 2018

F. Cámara ,
L. Ottolini ,
B. Devouard ,
L. A. J. Garvie  and
F. C. Hawthorne
F. Cámara*
Affiliation:
CNR-Istituto di Geoscienze e Georisorse, Sede di Pavia, via Ferrata 1, I-27100 Pavia, Italy
L. Ottolini
Affiliation:
CNR-Istituto di Geoscienze e Georisorse, Sede di Pavia, via Ferrata 1, I-27100 Pavia, Italy
B. Devouard
Affiliation:
Département des Sciences de la Terre, Université Blaise Pascal, UMR 6524 CNRS-UBP-OPGC "Laboratoire Magmas et Volcans", 5 rue Kessler, F-63038 Clermont-Ferrand, France
L. A. J. Garvie
Affiliation:
Department of Geological Sciences, Arizona State University, Tempe AZ 85287-1404, USA
F. C. Hawthorne
Affiliation:
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
*
*E-mail: [email protected]
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Abstract

Sazhinite-(La) is a new mineral from the Aris phonolite, Windhoek, Namibia. It occurs in vesicles within the phonolite, together with other species crystallized from late-stage hydrothermal fluids: natrolite, aegirine, microcline, apophyllite, sphalerite, analcime, fluorite, villiaumite, hydroxylapatite, galena, makatite, quartz, eudialyte, kanemite, tuperssuatsiaite and korobitsynite. Sazhinite-(La) forms small euhedral crystals up to 1 mm long and 0.4 mm wide, elongated along [001] and flattened on (010), exhibiting the forms {h0l}, {100} and {001}. It has good cleavage parallel to {010} and {001}. Twinning was not observed. Crystals are brittle with a Mohs hardness of 3, creamy white with a white streak, vitreous to pearly lustre, and translucent to transparent. In plane-polarized light, crystals are colourless with a = Z, b = Y, c = X. It is biaxial positive with α = 1.524, β = 1.528, γ = 1.544, all ±0.002, 2Vz(obs) = 46(1)°, and 2Vz(calc.) = 53.6°.

Sazhmite-(La) is orthorhombic Pmm2, a = 7.415(2), b = 15.515(3), c = 7.164(1) Å, and V = 824.2 Å3. One crystal was studied by X-ray diffraction, electron microprobe and secondary ion mass spectrometry (SIMS) microanalysis, leading to the average composition (Na2.87K0.02Sr0.01)Σ2.90 [La0.41Ce0.35Pr0.02Nd0.04(Sm,Gd,Dy,Er,Yb)Σ0.01Th0.09U0.01Y0.01Zr0.01Ca0.08Li0.01]Σ1.04 (S15.87S0.06B0.01) (O14.86F0.14).(H2O)2.

Weighted full-matrix least-squares refinement on 3369 reflections yielded Rall = 3.8%. The structure is built of corrugated [Si6O15]6- layers linked by [7]-coordinated REE and R4+ cations. This framework leaves channels that contain three [5]- and [6]-coordinated Na cations per formula unit that compensate for the residual charge on the silicate layers. The SIMS analyses confirm a Na content of 3 atoms per formula unit, leading to an ideal formula of Na3LaSi6O15(H2O)2. The third Na atom is bonded to H2O groups and therefore the total content of both Na and H2O may be reduced to 2 and 1 per formula, respectively. The depletion in Na allows for the entrance of high-charge cations such as Th4+.

Keywords

sazhinite-(La)new mineralEMPASIMSSCXRDrare-earth minerals
Type
Editorial
Information
Mineralogical Magazine , Volume 70 , Issue 4 , August 2006 , pp. 405 - 418
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2006

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References

Armbruster, T. and Gunter, M. E. (2001) Crystal structures of natural zeolites. Pp. 1–67 in: Natural Zeolites; Occurrence, Properties Applications (Bish, D. L. and D.W., Ming, editors). Reviews in Mineralogy and Geochemistry, 45, Mineralogical Society of America, Washington D.C. Google Scholar
Bartelmehs, K. L., Bloss, F. D., Downs, R. T. and Birch, J. B. (1992) EXCALIBR II. Zeitschrift für Kristallographie, 199, 185–196.CrossRefGoogle Scholar
Brown, I. D. and Altermatt, D. (1985) Bond-valence parameters obtained from a systematic analysis of the Inorganic Crystal Structure Database. Ada Crystallographica, B41, 244–247.Google Scholar
Brese, N. E. and O'Keeffe, M. (1991) Bond-valence parameters for solids. Ada Crystallographica, B47, 192–197.Google Scholar
Cámara, F., Garvie, L. A. J., Devouard, B., Groy, T. L. and Buseck, P. R. (2002) The structure of Mn-rich tuperssuatsiaite: a palygorskite-related mineral. American Mineralogist, 87, 1458–1463.CrossRefGoogle Scholar
Chao, G. Y., Grice, J. D. and Gault, R. A. (1991) Silinaite – a new sodium lithium silicate hydrate mineral from Mont Saint-Hilaire, Québec. The Canadian Mineralogist, 29, 359–362.Google Scholar
Es'kova, E. M., Semenov, E. I., Khomyakov, A. P., Kazakova, M. E. and Shumyatskaya, N. G. (1974) [Sazhinite, a new silicate of sodium and rare earths]. Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva, 103, 338–341.Google Scholar
Fleet, S. G. (1965) The crystal structure of dalyite. Zeitschrift für Kristallographie, 111, 349–368.CrossRefGoogle Scholar
Forbes, W. C., Baur, W. H. and Khan, A. A. (1972) Crystal chemistry of milarite-type minerals. American Mineralogist, 57, 463–472.Google Scholar
Garvie, L. A. J., Devouard, B., Groy, T. L., Cámara, F. and Buseck, P. R. (1999) Crystal structure of kanemite, NaHSi2O5.3H2O, from the Aris phonolite, Namibia. American Mineralogist, 84, 1170–1175.CrossRefGoogle Scholar
Ghose, S. and Wan, Che'ng (1978) Zektzerite, NaLiZrSi6O15: a silicate with six-tetrahedral-repeat double chains. American Mineralogist, 63, 304–310.Google Scholar
Haile, S. M. and Wuensch, B. J. (1997) Comparison of the crystal chemistry of selected MSi6O15-based silicates. American Mineralogist, 82, 1141–1149.CrossRefGoogle Scholar
Haile, S. M. and Wuensch, B. J. (2000) Structure, phase transitions and ionic conductivity of K3NdSi6O15. x H2O. II. Structure of β-K3NdSi6O15 . Ada Crystallographica, B56, 349–362.Google Scholar
Haile, S. M., Maier, L, Wuensch, BJ. and Laudise, R. A. (1995) Structure of Na3YSi6O15 – a unique silicate based on discrete Si6O15 units, and a possible fast-ion conductor. Ada Crystallographica, B51, 673–680.Google Scholar
Hawthorne, F. C., Kimata, M., Černý, P., Ball, N., Rossman, G. R. and Grice, J. D. (1991) The crystal chemistry of the milarite-group minerals. American Mineralogist, 76, 1836–1856.Google Scholar
Horváth, L. and Gault, R. A. (1990) Toute la minéralogie sur le Mont St Hilaire (Canada). Mineralogical Record, 21(4), 284–368.Google Scholar
Horváth, L., Pfenninger-Horváth, E., Gault, R. A. and Tarassoff, P. (1998) Mineralogy of the Saint-Amable Sill; Varennes and Saint-Amable, Quebec. Mineralogical Record, 29(2), 83–118.Google Scholar
Karpov, O. G., Podeminskaya, E. A. and Belov, N. E. (1976) Crystal structure of a K, Ce silicate with a three-dimensional anion framework: K2Ce Si6O15 . Soviet Physics Crystallography, 22, 382–384.Google Scholar
Mandarino, J. A. (1981) The Gladstone-Dale relation-ship: Part IV. The compatibility concept and its application. The Canadian Mineralogist, 19, 441–450.Google Scholar
Merlino, S. (1969) Tuhualite crystal structure. Science, 166, 1399–1401.CrossRefGoogle ScholarPubMed
Niedermayr, G., Gault, R. A., Petersen, O. V. and Brandstätter, F. (2002) Korobitsynite from the Aris phonolites, Windhoek, Namibia. Neues Jahrbuch für Mineralogie, 42–48.CrossRefGoogle Scholar
Ottolini, L., Camara, F. and Devouard, B. (2004) New SIMS procedures for the characterization of a complex silicate matrix, Na3(REE,Th,Ca,U) Si6Oi5.2.5H2O (sazhinite), and comparison with EMPA and SREF results. Microchimica Ada, 145, 139–146.CrossRefGoogle Scholar
Sheldrick, G. M. (1996) SADABS, Siemens area detector absorption correction software. University of Göttingen, Germany.Google Scholar
Sokolova, E., Hawthorne, F. C., Agakhanov, A. A. and Pautov, L. A. (2003) The crystal structure of moskvinite-(Y), Na2 K (Y,REE) [Si6O15], a new silicate mineral with [SigOis] three-membered double rings from the Dara-i-Pioz moraine, Tien-Shan mountains, Tajikistan. The Canadian Mineralogist, 41, 513–520.CrossRefGoogle Scholar
Shumyatskaya, N. G., Voronkov, A. A. and Pyatenko, Ya.A. (1980) Sazhinite, Na2Ce[Si6O14(OH)].nH2O: a new representative of the dalyite family in crystal chemistry. Soviet Physics Crystallography, 25, 419–423.Google Scholar
Upton, B. G. J., Hill, P. G., Hohnsen, O. and Petersen, O. V. (1978) Emeleusite: a new LiNaFeIII silicate from South Greenland. Mineralogical Magazine, 42, 31–34.CrossRefGoogle Scholar
von Knorring, O. and Franke, W. (1987) A preliminary note on the mineralogy and geochemistry of the Aris phonolite, SWA/Namibia. Communications of the Geological Survey of S.W. Africa/Namibia, 3, 61.Google Scholar
von Knorring, O., Petersen, O. V., Karup-Moller, S., Leonardsen, E. S. and Condliffe, E. (1992) Tuperssuatsiaite from Aris phonolite, Windhoek, Namibia. Neues Jahrbuch für Mineralogie Monatshefte, 145–152.Google Scholar
Supplementary material: File

Cámara et al. supplementary material

Table 6. Observed and calculated structure factors for sazhinite-(La) Vol. 70, June 2006

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