Iraqite, a New Rare-Earth Mineral of the Ekanite Group

A. Livingstone, D. Atkin, D. Hutchison and H. M. Al-Hermezi
Department of Geology, the Royal Scottish Museum, Edinburgh, EH1 1JF
Geochemical Division, Institute of Geological Sciences, 64/78 Gray's Inn Road, London WC1X 8NG
Nuclear Research Institute, Tuwaitha, Baghdad, Iraq

Summary: Iraqite, a new mineral of the ekanite group from northern Iraq, has the composition (Ln1·33 Th0·66 x0·15) (K1·07 y0·93) (Ca3·49 Ln0·35 Na0·16) (Si15·69 Al0·27) (O39·93 F0·07) where x = U, Pb, Zr, Fe, Mg, and Cu, and y is presumed to be vacant sites. It occurs in granite in contact with dolomitic marble. The colour is pale greenish yellow; H 4½ Dcalc 3·28 and Dmeas 3·27 (Berman balance), both corrected for minor impurity and non-structural water. Optically it is uniaxially negative with ω 1·590 and ε 1·585 though some sections show anomalous extinction up to 7°. Space group is P4/mcc with a 7·61±0·01 and c 14·72±0·02 Å. Strongest lines of the indexed powder pattern are 5·28(100), 3·31(100), 2·64(100), 7·36(80), 3·38(80), 3·40(60), 2·7(40), 7·62(30). Thermal data are given.

Mineralogical Magazine; March 1976 v. 40; no. 313; p. 441-445; DOI: 10.1180/minmag.1976.040.313.02
© 1976, The Mineralogical Society
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