Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-27T21:31:37.206Z Has data issue: false hasContentIssue false
  • English
  • Français

Cámaraite, Ba3NaTi4(Fe2+,Mn)8(Si2O7)4O4(OH,F)7. II. The crystal structure and crystal chemistry of a new group-II Ti-disilicate mineral

Published online by Cambridge University Press:  05 July 2018

F. Cámara ,
E. Sokolova  and
F. Nieto
F. Cámara*
Affiliation:
CNR — Istituto di Geoscienze e Georisorse, Unita di Pavia, Via Ferrata 1, I-27100 Pavia, Italy Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 Canada
E. Sokolova
Affiliation:
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 Canada Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry, Moscow, 119017, Russia
F. Nieto
Affiliation:
Dipartimento Mineralogia y Petrologia, Universidad de Granada, Av. Fuentenueva s/n, 18002 Granada, Spain
*
* E-mail: camara@crystal.unipv.it
Get access Rights & Permissions [Opens in a new window]

Abstract

Cámaraite — ideally Ba3NaTi4Fe82+(Si2O7)4O4(OH)4F3 — is triclinic, space group C, a = 10.6965(7) Å, b = 13.7861(9) Å, c = 21.478(2) Å, α = 99.345(1)°, β = 92.315(2)°, γ = 89.993(2)°, V = 3122.6(4) Å3, Z = 4, Dcalc. = 4.018 g cm–3, from the Verkhnee Espe alkaline deposit, Akjailyautas Mountains, Kazakhstan, has been solved and refined to R1 5.87% on the basis of 6682 unique reflections (Fo >4σF). The crystal structure of cámaraite can be described as a combination of a TS block and an intermediate (I) block. The TS (titanium silicate) block consists of HOH sheets (H-heteropolyhedral, O-octahedral), and is characterized by a minimal cell based on translation vectors t1 and t2, with t1 ~5.5 and t2 ~7 Å and t1 ^ t2 close to 90°. We describe the crystal structure of cámaraite using a double minimal cell, with 2t1 and 2t2 translations. In the O sheet, there are eight [6]-coordinated MO sites occupied mainly by Fe2+ and Mn, with minor Fe3+, Mg, Zr, Ca and Zn with <MO–ϕ> = 2.185 Å. Eight MO sites give, ideally Fe82+ p.f.u. In the H sheet, there are four [6]-coordinated MH sites occupied almost solely by Ti (Ti = 4 a.p.f.u.), with <MH–ϕ= = 1.963 Å, and eight [4]-coordinated Si sites occupied solely by Si, with <Si—0> = 1.621 Å. The topology of the TS block is as in Group II of the Ti-disilicates (Ti = 2 a.p.f.u. per minimal cell) in the structure hierarchy of Sokolova (2006). There are six peripheral (P) sites, four [8–12]-coordinated Ba-dominant AP sites, giving ideally 3 Ba p.f.u., and two [10]-coordinated Na-dominant BP sites, giving ideally 1 Na p.f.u. There are two I blocks: the I1 block is a layer of Ba atoms (two AP sites); the I2 block is a layer of Ba (two AP sites) and Na atoms (two BP sites). Along c, there are two types of linkage of TS blocks: (1) TS blocks link via AP cations which constitute the I1 block, and (2) TS blocks link via common vertices of MH octahedra (as in astrophyllite-group minerals) and AP and BP cations which constitute the I2 block. Cámaraite is the only mineral of Group II with two types of linkage of TS blocks and two types of I blocks in its structure. The relation of cámaraite to the Group-II minerals is discussed.

Keywords

cámaraitetitanium silicatecrystal structureTS blockgroup II
Type
Research Article
Information
Mineralogical Magazine , Volume 73 , Issue 5 , October 2009 , pp. 855 - 870
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

†

Permanent address: CNR — Istituto di Geoscienze e Georisorse, Unita di Pavia, Via Ferrata 1, I-27100 Pavia, Italy

References

Brown, I.D. (1981) The bond-valence method: an empirical approach to chemical structure and bonding. Pp. 1—30 in: Structure and Bonding in Crystals II (M. O’Keeffe and A. Navrotsky, editors). Academic Press, New York.Google Scholar
Cámaraite, F. and Sokolova, E. (2007) From structure topology to chemical composition. VI. Titanium silicates: the crystal structure and crystal chemistry of bornemanite, a group-III Ti-disilicate mineral. Mineralogical Magazine, 71, 593—610.Google Scholar
Cámara, F., Sokolova, E., Hawthorne, F.C. and Abdu, Y. (2008) From structure topology to chemical composition. IX. Titanium silicates: revision of the crystal chemistry of lomonosovite and murmanite, Group- IV minerals. Mineralogical Magazine, 72, 1207—1228.CrossRefGoogle Scholar
Guan, Ya.S., Simonov, V.I. and Belov, N.V. (1963) Crystal structure of bafertisite, BaFe2TiO [Si2O7](OH)2. Doklady Akademii Nauk SSSR, 149, 123–126. International Tables for X-ray Crystallography Vol. C (1992) Kluwer Academic Publishers, Dordrecht, The Netherlands.Google Scholar
McDonald, A.M., Grice, J.D. and Chao, G.Y. (2000) The crystal structure of yoshimuraite, a layered Ba- Mn-Ti silicophosphate, with comments of five- coordinated Ti4+ . The Canadian Mineralogist, 38, 649—656.CrossRefGoogle Scholar
Rastsvetaeva, R.K., Tamazyan, R.A., Sokolova, E.V. and Belakovskii, D.I. (1991) Crystal structures of two modifications of natural Ba, Mn-titanosilicate. Soviet Physics Crystallography, 36, 186—189.Google Scholar
Rastsvetaeva, R.K., Eskova, E.M., Dusmatov, V.D., Chukanov, N.V. and Schneider, F. (2008) Surkhobite: revalidation and redefinition with the new formula, (Ba3K)2CaNa(Mn,Fe2+,Fe3+)8 Ti4(Si2O7)4O4(F,OH,O)6. European Journal of Mineralogy, 20, 289—295.CrossRefGoogle Scholar
Rozenberg, K.A., Rastsvetaeva, R.K. and Verin, I.A. (2003) Crystal structure of surkhobite - new mineral from the family of titanosilicate mica. Crystallography Reports, 48, 384—389.CrossRefGoogle Scholar
Shannon, R.D. (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallographica A, 32, 751—767.Google Scholar
Sheldrick, G.M. (1997) SHELX-97: Program for the Solution and Refinement of Crystal Structures. Siemens Energy and Automation, Madison, Wisconsin, USA.Google Scholar
Sheldrick, G.M. (1998) SADABS User Guide, University of Gottingen, Germany.Google Scholar
Sokolova, E. (2006) From structure topology to chemical composition. I. Structural hierarchy and stereochemistry in titanium disilicate minerals. The Canadian Mineralogist, 44, 1273—1330.CrossRefGoogle Scholar
Sokolova, E. and Cámaraite, F. (2007) From structure topology to chemical composition. II. Titanium silicates: revision of the crystal structure and chemical formula of delindeite. The Canadian Mineralogist, 45, 1247—1261.CrossRefGoogle Scholar
Sokolova, E. and Cámaraite, F. (2008a) From structure topology to chemical composition. III. Titanium silicates: crystal chemistry of barytolamprophyllite. The Canadian Mineralogist, 46, 403—412.Google Scholar
Sokolova, E. and Cámaraite, F. (2008b) From structure topology to chemical composition. VIII. Titanium silicates: the crystal structure and crystal chemistry of mosandrite from type locality of Laven (Skadon), Langesundsfjorden, Larvik, Vestfold, Norway. Mineralogical Magazine, 72, 887—897.CrossRefGoogle Scholar
Sokolova, E. and Hawthorne, F.C. (2008a) From structure topology to chemical composition. IV. Titanium silicates: the orthorhombic polytype of nabalamprophyllite from Lovozero massif, Kola Peninsula, Russia. The Canadian Mineralogist, 46, 1469—1477.Google Scholar
Sokolova, E. and Hawthorne, F.C. (2008b) From structure topology to chemical composition. V. Titanium silicates: the crystal chemistry of nacar- eniobsite-(Ce). The Canadian Mineralogist, 46, 1493–1502.Google Scholar
Sokolova, E., Abdu, Y., Hawthorne, F.C., Stepanov, A.V., Bekenova, G.K. and Kotel’nikov, P.E. (2009a) Cámaraite, Ba3NaTi4(Fe2+,Mn)8(Si2O7)4O4(OH,F)7. I. A new titanium-silicate mineral from the Verkhnee Espe Deposit, Akjailyautas Mountains, Kazakhstan. Mineralogical Magazine, 73, 847–854.CrossRefGoogle Scholar
Sokolova, E., Cámaraite, F., Hawthorne, F.C. and Abdu, Y. (2009b) From structure topology to chemical composition. VII. Titanium silicates: the crystal structure and crystal chemistry of jinshajiangite. European Journal of Mineralogy, 21, 871—883.CrossRefGoogle Scholar
Takeuchi, Y., Ohashi, Y., Sawada, H. and Haga, N. (1997) Crystal structure of yoshimuraite (Ba,Sr)2(S,P)O4Mn2OH[Si2O7TiO], with discussion on its local symmetry. Pp. 253—264 in: Tropochemical cell-twinning (Y. Takeuchi, editor). Terra Scientific Publishing Company, Tokyo.Google Scholar
Yamnova, N.A., Egorov-Tismenko, Yu.K. and Pekov, I.V. (1998) Crystal structure of perraultite from the coastal region of the Sea of Azov. Crystallography Reports, 43, 401—410.Google Scholar
Zhou, H, Rastsvetaeva, R.K., Khomyakov, A.P., Ma, Z. and Shi, N. (2002) Crystal structure of new mica-like titanosilicate-bussenite, Na2Ba2Fe2+(TiSi2O7)(CO3) O(OH)(H2O)F. Crystallography Reports, 47, 43—46.CrossRefGoogle Scholar
Supplementary material: File

Cámara et al. supplementary material

Cif file

Download Cámara et al. supplementary material(File)
File 154 KB
Supplementary material: File

Cámara et al. supplementary material

Structure factors

Download Cámara et al. supplementary material(File)
File 365.7 KB