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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
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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

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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

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