Iranian Journal of Crystallography and Mineralogy
Year:2011 | Volume:19 | Issue:3|Papers Count:17

Zn0.97 TM0.03O (TM=Co, Fe) thin films were deposited onto glass substrates by the sol–gel method and the effects of transition metals substitution on structural and optical properties of ZnO films were investigated. The X-ray diffraction patterns revealed that the films have wurtzite structure. Optical transmittance of the films was recorded in the range of 200 -800 nm wave length and the band gap of the films was determined. The absorption edge of the films showed a small shift depending on the substitution elements. The optical constants of the films were calculated by using pointwise unconstrained minimization algorithm.

this research is concerned with properties and characteristics of Qazandaqy Kaolin deposit in Takestan, Qazvin Province. Physical, chemical and microstructural analysis for raw materials and treated of 1160oC were carried out andare composed of kaolin of England, Russia and Zenoz (Marand, Iran). XRF analysis indicated the average content of 20.54% for Al2O3 and 55.66% for SiO2. XRD analysis of raw materals contains kaolin, quartz and illite phases of treated kaolin at 1160oC designated a conversion to mulite and cristoballite. For industrial ceramic usage, low kaolin samples were selected for ceramic tests and the results indicate of suitable quality for production of tiles as well as some porcelanis.

The Qatruyeh iron occurrences are located in the eastern edge of the Sanandaj-Sirjan metamorphic zone, southwestern Iran (at 50 Km northeastern of Neyriz), and are hosted by a Late Proterozoic to Early Paleozoic sequence which is dominated by metamorphosed carbonate rocks. The Iron ores occur as layered, massive and disseminated magnetite and in lesser amount as hematite-bearing veins and veinlets. Mineralogical studies on host rock and iron ores indicate that magnetite mineralization was occurred in relation to pervasive Na-Ca alteration. The stage is shown by spread metasomatic replacement textures, gradational contact between magnetite ore and host rock and mineral assemblages of magnetite + actinolite + quartz + titanite + dravite + paragonite + siderite ± tremolite ± pyrite ± chalcopyrite. Fluid inclusion data on quartz minerals accompanied by ores indicate that metamorphic-hydrothermal fluids caused magnetite mineralization at temperatures between 285 and 345oC with salinities between 3.5 and 15 weight percent NaCl equivalent at pressures below 280 bars, at greenschist to amphibolite metamorphic conditions. The brittle and ductile deformation regimes result in remobilization of metamorphic fluids and iron ore precipitation along the wide ductile shear zones, lithological boundaries and superficial fractures. Physicochemical changes by interaction of fluids with carbonates can be effective mechanisms of iron ore precipitation due to cooling and condensation, effervescence, increasing of pH and pCO2, break the ligands and decreasing of H2O dielectric constant.

The ore bodies of Galali and Baba-Ali are two relatively important iron ore deposits in west Iran. These ore deposits are situated in the Sanandaj-Sirjan zone. The deposits are associated with ultramafic, calc-alkaline, carbonatite and other rocks. Macroscopic observations, on the boreholes, show that one of the rare ultramafic rocks (hornblendite) appears in all various horizons parallel to magnetite. Petrological and mineralogical study (microscopic) show that two kinds of hornblendite exist: a) hornblendite with flow-texture and b) without flow-texture. Latter contain only one generation of amphibole. The major rock-forming mineral in this hornblendite is actinolite, which may contain minor concentration of diopside which probably is originated from pyroxenite by late stage supercritical solutions. Other rocks with flow-texture (hornblendite typeII) contain two generations of amphiboles. The first generation generated the flow-texture. Chemical compositions of rock-forming minerals are actinolite or actinolite hornblende and Tschermakitic hornblende. The second generation of amphibole is resulted by recrystallization of first generation. On the basis of XRF analyses, hornblendites are calc-alkaline to low-K tholeitic series into Chemical data of microprobe and regional tectonic indicate that the origin of magma was related to an intra-continental rifting. The subduction processes which were active up to Pliocene, also affected it.

Plio-Quaternary potassic to high potassic basaltic rocks are found in northern part of Uromieh-Dokhtar Magmatic Arc in NW Iran. The mineralogical composition of these rocks characterized with phenocrysts of Cpx, phlogopite, leucite and olivine in groundmass of plagioclase, sanidine, Cpx and biotite. Phlogopite phenocrysts display a euhedral platy form with reaction rims. Based on the International Mineralogical Association scheme, the phologopite compositions plot between siderophyllite and eastonite end members and show Fe/ (Fe+Mg) ratios <0.33. Based on their TiO2, MgO, MnO and AlVI content, they are primary magmatic micas. The micas contain up to 5 wt% BaO and 8.62 wt% TiO2 and indicate similarity in composition with barian titanian phlogopites from other potassic volcanic rocks in the world. As BaO, Al2O3 and TiO2 increase, the SiO2, FeO, MgO and K2O decrease. In this regard, Different substitutions deduced from such variations, which is common to most magmatic barian micas are discussed. In comparison with other potassic and high potassic volcanic rocks, the studied phlogopites display similarity with phlogopites of Italian Roman type volcanic rocks.

The Jajarm bauxite deposit is a part of the Irano-Hymalayan karst bauxite belt which is located about 175 km southwest of Bojnourd. This deposit has been developed as a stratiform horizon along the contact of Triassic dolomites and the Jurassic shales and sandstones. The basal contact zone of the bauxite horizon is mainly undulatory, and bauxite fills cavities in the footwall dolomite, whereas the upper contact zone is concordant with the hanging-wall shales and sandstones. Textural analysis indicates both allochthonous and autochtonous origins for the bauxites. Diaspore, bohemite, gibbsite, chamosite, hematite, goethite, clay minerals, anatase, cancrinite, crandallite, pyrite, and quartz were identified in the ore paragenesis. These minerals are developed during three stages of weathering, diagenetic and epigenetic processes. Combination of mineralogical and geochemical data show that this deposit formed during two main stages. First, bauxite materials, Fe and Ti oxides and clay minerals were developed as authigenic bauxitization processes of alkaline basaltic parent rock. During the second stage, these materials were transported to karst depressions, where they accumulated as a relatively thick bauxite horizon.

Agate mineralization in the Mianeh area is occurred in the open space filling form in the Eocene volcanic acidic rocks. High potassic and shoshonitic nature of the volcanic rocks have been related to active continental margin setting. The host rocks of the agates are mainly ignimbrite and rhyolite. Blue, red, orange, grey, green and black colors, stelled, cauliflower, fibrous, radiated, circular structures and banded and fibrous textures are seen in the agates. The most important factor causing blue color is copper and for black, red and smoky colors are iron and manganese. Samples have good polishibility and transparency, hardness is 6.7-7 and density is 2.64. Fluorescence and pleochroism features are lacking. The aluminum and volatile amounts show decreasing versus increasing of the silica in the agates. The behavior of REE shows a similar magmatic nature for the studied agates. Practical experiences showed that the best temperature for artificial dyeing for red and orange colors is 500oC and for light-dark blue is 550oC.

The protolith of rodingitic dykes of Naien area are pegmatoidic gabbros, microgabbros, dolerites and fewer amphibolites. Textural features and thickness are effective parameters for rodingitization of these dykes. Slight thickness of microgabbro and pegmatoidic dykes have more undergone rodingitization and have passed the primary to advanced stages of static rodingitization (due to the presence of epidote, Prehnite and hydrogrossular, Mg-chlorite, tremolite and secondary diopside replacement minerals as well as dynamic rodingitization (Owing to the xonotlite, prehnite and pectolite vein mineral), while doleritic and amphibolitic dykes have only passed the primary stage of static rodingitization (due to the presence of epidote, Prehnite and hydrogrossular).

The Pliocene calc-alkaline volcanic rocks are exposed in two areas in southeast and northwest of Isfahan and consist of andesites and dacites. Based on geochemical data and multielements pattern, these rocks are medium to high calc-alkaline suite and they show LILE and LREE enriched normalized multi-element patterns, and negative Nb and Ti. Condritenormalized REE patterns display a steep decrease from LREE to HREE without any Eu anomaly. They have higher SiO2 and Sr content and Sr/Y and La/Yb ratios and low MgO, Mg#, Y and Yb contents than the normal calc-alkaline volcanic rocks. These volcanic rocks show adakite characteristics. These features are consistent with ratios obtained from orogenic related volcanic rocks. These rocks may have been produced by partial melting of thickened lower continental crust or slab probably transformed to eclogite or garnet -amphibolite. HREE and Y depleted pattern suggest the existence of garnet and amphibole as a residue in the source.

Little information is available on the provenance, evolutionary trend and characteristics of the loess deposits in northeast Iran. These deposits are thought to be related to Quaternary paleoclimate. Studies of mineralogical, surface textures and geochemical composition and trace elements in these loesses in Golestan Province suggest that they are mostly derived from felsic igneous rocks (granitic or granodioritic). The studied loess samples display uniform chemical composition, suggesting a similar alteration history. Chemical index of alteration suggest a weak to moderate degree of weathering in a felsic source area. Whole-rock analyses indicate that the abundance and composition of heavy minerals such as zircon, tourmaline, apatite, titanite, and phyllosillicate minerals (e.g. chlorite, biotite and muscovite), derived from felsic magmatic sources, exert a significant control on the chemical composition. Scanning electron micrographs of quartz grains indicate an abundance of silt-sized quartz probably resulting from glacial processes active in Pleistocene followed by aeolian transport from the arid to semiarid Central Asian southern desert (Turkmenistan, Tajikistan and Uzbekistan great deserts). Seemingly, local topography of northeast Iran, acted as a major barrier, entrapping the airborne dusts.

Extrusive igneous rocks are formed the main part of geological units in northeast region of Birjand. Investigation shows that these igneous rocks can be divided into rhyolitic, dacitic, andesitic and an especial group including basaltic andesite and basalts. In Later group that differ from the others according to geochemical and mineralogical characteristics, there are limited outcrops of high-K basaltic andesite, benmorite and mogearite in addition to medium-K basaltic andesites and subalkaline basalts. The composition of olivine in basaltic andesites (Fo 0.67) and basalts (Fo 0.73) is crysolite and the composition of pyroxene is diopside in basalts, augite in basaltic andesites and enstatite in andesites. The chemistry of amphiboles in intermediate volcanic rocks shows that their compositions are magnesiohornblende to tschermakite hornblende.

The studied area is located in the west Azerbaijan Province at north-west of Serow town. Variety of metamorphic rocks including metabasites, marbles and metaperidotites crop out in the area. The metabasites are metamorphosed under greenschist to amphibolite facies. The metamorphosed calcareous rocks are mainly marble in which calcite form more than 90% volume of the rocks. The metaperidotites are serpentinized. Degree of serpentinisation is different from low to high. The protolith composition of the metapridotites is determined as harzburgite and lherzolite on the basis of petrography, mineralogy, textural relations and geochemical data. Considering sequence of the metamorphic reactions and thermometry studies in the metaperidotites, the highest temperature for formation of tremolite and serpentine in these rocks are ~780oC and ~480oC respectively. Using the whole rock chemistry and chemical diagrams, the Serow serpentinized metaperidotites are located in the metamorphic peridotites field. On the basis of textural relations and geochemical data, the oceanic crust and ophioliterelated origin of the investigated serpentinized metaperidotites are more likely.

Study of physical and chemical characteristics of dust storms in Iran is necessary. In this regard, 10 samples from Khozestan dust storms in 1387 and 1388 were collected for XRD and SEM studies. XRD result show that mineralogical composition of these dust particles can be divided into three groups: (1) Carbonate group (calcite mineral), (2) Silicate group (quartz mineral) and (3) Clay group (Kaoline mineral). The most important minor phase is Gypsum. SEM studies indicate that these particles were found in rounded, irregular, prismatic and rhombic shapes. Average size of these particles ranges from 2 to 44 mm. Minimum and maximum sizes were reported for clay, sulfate and carbonate minerals. In general, dust particles in Khuzestan dust storms were distributed in 2 to 52 mm but 10 to 22 mm is dominant size of these particles.

There are scattered exposures of young volcanic rocks in Hamun Lake Area in south western and north western of Zabol in east of Iran. The microscopic evidences and geochemical analysis show that these rocks are olivine basalt and basalt to trachy basalt. The main textures of these rocks are porphyry, microlitic porphyry and vesicular. The main phenocrysts of these rocks are olivine, clinopyroxene (Diopside) and some plagioclase (Labradorite). Tectonomagmatic studies indicate that these rocks are formed in intracontinental environment in Helmand block and have sodic alkaline nature. These rocks can be the production of extension which has occurred after compressional regime in east of Iran. Enrichment of LREE to HREE ratio indicates that the parent magma has probably formed by low partial melting of garnet lherzolitic mantle.

Granitoidic bodies of the eastern Misho mountains (SW Marand-East Azerbaidjan) have intruded into Kahar Formation and mafic-ultramafic rocks of Misho mountains and has faulty contact with Triassic carbonate deposits. The composition of these bodies ranges from quartz monzonite to granite and alkali-granite and it is cut by porphyritic granitic and diabasic dykes. The main minerals of these bodies are pertitic alkali feldspar, quartz and Na-rich plagioclase, accompanied by lesser amounts of biotite and amphibole. In this regard, these bodies belong to hypersolvus granitoids and A2 sub-group of A-type granitoids. The parental magma of these bodies has calc-alkaline to shoshonitic characteristic and show positive anomalies of LILE and LREE, and obvious negative anomalies of Ba, Eu, and HREE. These bodies have emplaced in a post-collisional tectonic setting related to tensional movements after Hercynian orogenic phase and have formed by melting of crustal rocks.

Cheshmeh-Zard Au-As-Sb mining area is located in south west of Nyshabour. Twenty one samples were collected from vein mineralization, stream sediments and agricultural land, as well as seven samples from drinking and spring waters from Arghash and Hassanabad villages. Based on high level of arsenic and antimony contamination, two areas were recognized in vein mineralization and surrounding drainages as follows: 1) Gold-arsenic ± antimony vein mineralization in Cheshmehzard village. 2) Antimony-arsenic vein mineralization in southeast of Arghash village. These areas can be the source of environmental contamination in this region and ecosystem of district has been affected by them. Based on comparison with USEPA standard, the arsenic and antimony in the collected samples from agricultural land were lower than standard limit. Unfortunately, arsenic in the drinking water of Hassanabad village was 23 times and antimony was 3 times more than standard. High contents of arsenic and antimony are dangerous to people who lived in the study area. These two heavy metals may cause cancer and skin problems for the people, which detailed studies, need to be done on the reasons of death in villages. Thus, it is recommended to supply the healthy drinking water for the people from nearby.