Iraqi Bulletin of Geology and Mining

The Cretaceous rocks, in Iraq, are characterized by their well development all over the country, on the contrary to the rocks of other geological periods. The Cretaceous rocks are exposed widely in the Iraqi Western Desert, as well as in the northeastern and northern parts of the country. They are also exposed in Sinjar and Qara Chauq mountains. The main rock types are carbonates, marl, phosphorites, shales and fine clastics. Conglomerates are also known, but only in the northeastern part of the country. Igneous complexes and metamorphic rocks are limited to the northeastern part of Iraq. The thickness of the Cretaceous rocks is highly variable, not only in different parts of Iraq, but even in one single formation. As a whole, the thickness decreases towards southwest of the country.

Mollusk shells of C. (Corbicula) fluminalis (MULLER) and Unio tigridis (BOURGUIGNAT) were collected from 14 sites along the Euphrates River from Kerabla to Nassirriyah. The shells were analysed for their Sr, Ca and Na contents and examined by XRD for mineral composition.
The results were compared to the water main constituents of cations and anions as well as the total dissolved salts (TDS) reported in water samples collected from the same sites and in the same year. The results show that Sr and Na concentrations as well as Na/ Ca ratio are directly correlated with the TDS of the water and also with the water content of dissolved Na+, Ca2+, SO42- and Cl-.
The nature of Sr and Na presence in these aragonite shells is believed to be in substitution for Ca in the aragonite structure. The Sr and Na contents of the Recent shells in the present study is much higher than that reported in ancient limestones. Strontium and sodium may be expelled and remobilized when aragonite alters to calcite during diagenesis.

A high grade phosphate concentrate , with P2O5 content about 31% and less than 0.7% MgO was successfully obtained from Wadi Hirri Al-Gharbi dolomitic phosphorite deposit (Area I) using simple sizing and classification processing. The yield (about 59%) and phosphate recovery (about 80%) are good as compared with those gained previously from other phosphate localities.

During the year 2002 a quality management system , based on the international specifications (ISO 9001/2000) , has been prepared to control the geological survey and mineral investigation operations in the State Company of Geological Survey and Mining, Items of the original specifications had to be modified to match the nature of the company activities . Preliminary results of applying the adopted system in the field of geological survey and mineral investigation showed positive indications in the obtained results.
The new measures involved all stages of each project starting with planning which included important and clear quality procedures , such as plan inputs and outputs , ways of verification , follow up and approval . The new project plans differ qualitatively from the previous ones prepared before adopting the new system. Besides, the scientific and technical reports which are considered as the end product of each project are subject to numerous procedures including method, review, verification and approval. The application of the new system led to improvement of quality and style of the final reports gaining more, confidence and reliability.

Abu Skhair area was subjected to systematic mineral and mining exploration operations to evaluate the uranium mineralization discovered in a location within Hor Al–Jebssa area close to Al-Zejrey village. The obtained data are valuable to contribute to the origin and mode of formation of the uranium deposit in the area, which this study deals with.
The uranium deposits of Abu Skhair consist of non-uniform gray to dark gray marly limestone layer of variable thickness ( 0.2-4.7 m ) rich in organic materials and broken fossil shells. A part of distinguishable radioactivity, can be markedly recognized by sharp colour change of the underlying limestone rock bed of orange to yellow colour.
According to the conclusion of this study, the uranium of Abu Skhair deposit originated from a specific limestone layer within the Euphrates Formation (Lower to Middle Miocene) which contains about 80ppm U3O8 on average and it is considered as source rocks for the uranium deposit in the area.
The source rocks were exposed and oxidized due to regression of the Miocene sea level, consequently, their uranium contents were partially leached.
The exposed Euphrates rocks in the semi-consolidated stage were affected by wave action of enough energy to smash the fossil shells contained in the limestone rocks. The relics of the hashed shells were sorted and deposited later by low energy wave action as indicated by upward fining of shell fragments relics.
It seems that marsh and swamp environment were developed in the area and furnish reduction conditions by which the leached uranium was precipitated partly in a form of very fine grain uraninite and partly in an absorbed form by the organic materials and clay minerals forming the uranium mineralization horizon in the area.

This research was carried out on laboratory scale in the laboratories of the State Company of Geological Survey and Mining.It deals with the possibility of the alum preparation from the white kaolin of Dwaikhla locality-Western Iraqi Desert which contains 33 % Al2O3. The result of this study indicate that after treatment of the calcined kaolin ( at 725 C0 ) with 30% by wt. H2SO4 for 45 min , alum can be prepared with specification identical to that used in drinking water treatment plants .

This paper deals with the evaluation of flint clay of the karst–fill deposits (North Hussainiyat, Western Desert) and white kaolinitic clay of the Ga´ara Formation (Dwaikhla area) in terms of mineral, refractory and chemical properties. Testing of raw materials revealed that the kaolinitic clay samples contain higher amounts of impurities and fluxes and lower alumina as compared to the flint clay samples.
Accordingly, these clays were prepared for the laboratory tests. Part of the samples was fired at (1400)ºC to prepare a grog .The grog samples were subjected to grinding and sieving and were mixed with the unburned clay samples using two mixing ratios of (75 : 25) and 80 : 20 (burned clay: unburned clay). The samples were formed into small bricklets using semidry press at (49) N/mm2 and (8 %) humidity. The samples were dried at (110)ºC and fired at (1400)ºC with (2) hrs soaking time.
The mineral phases of the burned samples were identified by X- ray diffraction and the microtextures were examined by scanning electron microscope .The amount of mullite formed after firing was estimated using chemical method. Thermal shock and chemical resistivety were determined for both types.
The results show the superiority of the samples prepared from flint clay in the properties examined which may be explained by the higher mullite formed in these clays after firing as compared to those prepared from kaolinitic clay. Mullite helped in maintaining thermal stability and high chemical resistance in the fired products.