Hostname: page-component-78c5997874-j824f Total loading time: 0 Render date: 2024-11-20T00:42:26.833Z Has data issue: false hasContentIssue false
  • English
  • Français

Baghdadite, a new calcium zirconium silicate mineral from Iraq

Published online by Cambridge University Press:  05 July 2018

H. M. Al-Hermezi ,
D. McKie  and
A. J. Hall
H. M. Al-Hermezi
Affiliation:
Department of Applied Geology, University of Strathclyde, Glasgow G1 1XJ
D. McKie
Affiliation:
Department of Earth Sciences, University of Cambridge CB2 3EQ
A. J. Hall
Affiliation:
Department of Applied Geology, University of Strathclyde, Glasgow G1 1XJ
Get access Rights & Permissions [Opens in a new window]

Abstract

Baghdadite, a new calcium zirconium silicate mineral has been found in melilite skarn in contact with banded diorite, from the Qala-Dizeh region, NE Iraq. Electron microprobe analysis yielded: SiO2 = 29.26, ZrO2 = 27.00, TiO2 = 2.11, Fe2O3 = 0.11, Al2O3 = 0.03, MgO = 0.05, CaO = 41.44, Na2O = 0.02, sum = 100.02 wt. %. The mineral contains about 0.16% HfO2. This analysis calculates to Ca3.00(Zr0.89Ti0.11)(Si1.98Fe0.01)O9 which leads to the ideal formula Ca3Zr[O2|Si2O7]. X-ray single crystal study showed it to be monoclinic with space group P21/a. The unit cell dimensions are: a = 10.42(2), b = 10.16(2), c = 7.36(1) Å, β = 91.1°, Z = 4 and cell volume = 779.04 Å3. The seven strongest lines in the powder diffraction pattern are (d,I,hkl): 7.30 (45)(110), 3.23 (80)(130), 3.04 (75)(2̄02), 2.98 (85)(202), 2.88 (70)(320,212), 2.84 (100)(230), 1.702 (40)(522). It is colourless, lustre vitreous, no cleavage and VHN50 = 725–783 kg mm−2 with H ∼ 6. Calculated density = 3.48 g cm−3 which is very close to 3.46 measured density of a synthetic Ca3ZrSi2O9. It is optically biaxial, positive, 2 V ∼ 72°, dispersion indiscernible. The cathodoluminescence colour is dull grey with a greenish tint. Refractive indices: α= 1.652, β = 1.658, γ = 1.670. The crystal habit is stumpy prismatic and a contact twin with b as twinning axis is observed. Optic orientation: α = c, β//b, γ = a.

Keywords

baghdaditenew mineralQala-Dizeh regionIraq
Type
Mineralogy
Information
Mineralogical Magazine , Volume 50 , Issue 355 , March 1986 , pp. 119 - 123
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1986

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.)

References

Aarden, H.M. and Gittins, J. (1974) Can. Minera. 12, 241-7.Google Scholar
Al-Hermezi, H.M. (1985) Mineral. Mag. 49, 739-44.CrossRefGoogle Scholar
Gossner, B., and Kraus, O. (1934) Cbt. f. Mineral Geol. Pal.A, 72-9.Google Scholar
Kordyuk, R.A., and Gul'ko, N.V. (1962) Dokl. Akad. Nauk SSSR. 142, 639-41.Google Scholar
Livingstone, A., Atkin, D., Hutchison, D., and Al-Hermezi, H.M. (1976) Mineral. Mag. 40, 441-5.CrossRefGoogle Scholar
Matthewman, J.C. Thompson, P., and Brown, P.J. (1982) J. Appl. Crystallogr. 15, 167-73.CrossRefGoogle Scholar
Nickel, E.H., Rowland, J.F. and Maxwell, J.A. (1958) Can. Mineral. 6, 264-72.Google Scholar
Peacock, M.A. (1937) Norsk. Geol. Tidsskr. 17, 17.Google Scholar
Skripchenko, N.S. (1960) Mem. All-Union Mineral. Soc. 89, 346-7.(in Russian).Google Scholar
Smirnova, R.F., Rumanova, I.M., and Belov, N.V. (1955) Zap. Vses. Mineral. Obshch. 84, 159.Google Scholar
Zharikov, V.A., Shmulovich, K.I., and Bulatov, V.K. (1977) Tectonophys. 43, 145-62.CrossRefGoogle Scholar

A correction has been issued for this article:

Errata