The silica sand deposits in the western desert of Iraq : an overeview

الملخص EN

Very large silica sand deposits are documented at the Western Desert of Iraq.

These deposits are found in the Ga'ara (Lower Permian), Hussainiyat (Lower Jurassic), Najmah (Upper Jurassic), Nahr Umr (Lower Cretaceous) and Rutbah (Upper Cretaceous) formations.

Other exposed formations, such as the Amij Formation (Lower Jurassic) incorporates some thick silica sand horizons but not yet investigated for economic potentiality.

Petrographic studies revealed that these silica sands are mostly weakly-cemented quartz-arenite, consisting predominantly of quartz and traces of alkali feldspars, heavy minerals and clay mineral.

Some of these deposits are associated with kaolin clays, such as the Ga'ara, Hussainiyat and Amij formations.

The Ga'ara and Hussainiyat deposits are of fluvial origin, whereas the Amij, Najmah, Nahr Umr and Rutbah deposits are of fluvio-paralic origin.

The X-ray diffractograms revealed that the main associated clay mineral is kaolinite with minor proportions of illite and mixed-layer illite-smectite.

The other main admixtures present, beside quartz, are iron oxyhydroxides (mostly goethite) and anatase.

Particle size of the silica sand deposits ranges from very fine to coarse but the most common are fine to medium grain size.

The shape of the grains is sub-angular to sub-rounded and the Fe2O3 ranges between (0.01 – 1.5) %.

Follow-up investigations were carried out on five localities to estimate, verify and categorize the quantity and quality of the silica sand deposits.

The investigations resulted in estimating 15.9 million m3 of silica sand on category B, 2.2 million m3 on category C1 and 4456.9 million m3 on category C2.