Iranian Journal of Crystallography and Mineralogy
Year:2019 | Volume:27 | Issue:1 |Papers Count:24

Zaveh copper mineralization is located SE of Torbat-e-Hydarieh in Khorasan Razavi Province, in Khaf-Kashmar-Bardaskan Metallogenic Zone. Geology of the area includes Jurassic and Cretaceous sedimentary rocks and Eocene andesitic to rhyodacitic volcanic rocks. Mineralization is structurally controled and occurred as vein-veilet form with east-west ternding and hosted by Jurassic silicate-cemented conglomerate. Primary minerals are chalcopyrite, pyrite, and arsenopyrite and secondary minerals include malachite, azurite, chalcocite, covellite, bornite, copper sulfates, wad (hydroxide manganese), hematite, goethite, jarosite, limonite, and minor chrysocolla. Quartz is the most important gangue mineral associated with vein mineralization. Primary minerals often seen with vein-veilet and disseminate texture and secondary minerals mostly have vein-veilet and secondary substitution texture. Silicification is the dominant alteration associated with vein mineralization. Mineralization has anomaly of Cu (max 2. 1%), As (up to 1%), Sb (105 ppm), Pb (4371 ppm), and Zn (max 1. 1%). Based on two-phases (LV) fluid inclusion studies in quartz mineral, minimum formation temperature of mineralization is 310 to 387º C. It is formed by NaCl and CaCl2-bearing fluid with 8. 1 to 15. 8 wt. % salinity. Two isothermal fluid with different salinity played role in the formation of mineralization. Ore-fluid with 14 to 16 wt. % salinity, which itself resulted from mixing of magmatic and meteoric water, was mixed with another fluid with the same temperature range but lower salinity (between 8-9 wt. % salinity). Reduction of temperature can be important factor for sulfide deposition. Host rock, structural control of mineralization, alteration type and development, moderate temperature and low salinity of ore-fluid, and simple mineralogy of Zaveh mineralization is similar to hydrothermal vein-type deposits.

Amphibolite rocks with mylonitic texture exposed in the NE of Yan-Cheshmeh village (SE of Zayandeh-Rud Lake). Mineralogy of rocks include amphibole, plagioclase, quartz, rutile, clinozoesite, chlorite, titanite, biotite and opaque. Amphiboles are seen as fish. Basic igneous rocks are protolith of the amphibolites that have subalkaline nature. Ni (299-370 ppm), Cr (1169-1900 ppm) and SiO2 (44. 91-49. 20 %Wt) contents highly resemble to unfractionation magmas. Chondrite normalized REE patterns exhibit pronounced LREE enrichment relative to HREE without Eu anomaly. Low TiO2, Zr, P2O5 and Nb/Y contents with enrichment of LREE and negative Nb anomaly are pronounced characters of continental flood tholeiitic basalt within plate magmatism. Tholeiitic affinities, low values of alkali elements, high MgO, FeO, Cr and Ni contents suggest high partial melting in an extensional setting of continental within-plate with rapid decrease in pressure, resulting in high rate of partial melting and quick uplift which are effective factors for the formation of basaltic protolith of the amphibolites.

In the Hamedan region, migmatitic rocks with various structures cropped out that stromatic structure is the most abundant. Index minerals of metapelites such as garnet (almandine), staurolite, andalusite, sillimanite, kyanite, fibrolite, cordierite, plagioclase (andesine) and spinel (hercynite) are present in these rocks. Garnet has occurred in all three parts of leucosome, paleosome, and melanosome of migmatites and has been affected by various metamorphic events (progressive, retrograde, and partial melting). Garnets have continuous and discontinuous chemical zoning for index elements Fe, Mg, Mn and Ca, where the behavior of these elements is not the same. Some factors such as the presence of multi-nucleus single crystals, the participation or none participation of garnets in the process of partial melting and polymetamorphism of area have important role in it. The discontinuity in the growth of crystals represents a re-growth during an individual metamorphic event, and it can represent two metamorphic events.

Opal, known as Aghigh in Persian, is one of the main semi-precious rock in Iran that is present in Bayag active mine in NW of Torbat Heidarieh. Mineralogy of agate is crucial for its treatment and cutting. In this research, mineralogy of agate in Bayeg mine investigated using SEM, Raman analyses and ICP methods. Chalcedony introduced as the main constituent of agate in literature. However, this research revels opal, chalcedony and moganite are main minerals of Bayeg mine respectively. In hand specimen, chalcedony show white and milky color, and opals are gray to dark. ICP-MS analysis showed that amounts of AL and Na, Ba and Sr present as trace of meteoric and hydrothermal fluids and igneous activities during the formation of opals

The study area is located at the eastern Urmia Lake near Aghgonbad village with 1Km distance from Eslami peninsula. The rocks are under saturated and belonging to the Cenozoic to Pelio-Quaternary with shoshonitic affinities and are phonolite to luecitite. The chondorite normalized REE patterns show LREEs enrichment related to HREEs. Some geochemical characteristics are correlated with continental within-plate setting and have post-collisional resemblance accompany with crustal contamination. Crystal Size Distribution (CSD) patterns have been drawn for leucite, pyroxene and olivine crystals. It is observed that the curve is fractured and curvature for leucite, with fine and coarse grains, that is sign of two magma mixing. But the patterns for olivine and pyroxene are linear. The average times for nucleation, growth and suspension at the chamber for leucite fine grains and olivine are less than 100 years and for pyroxene and coarse leucites residence time are >200 years, if growth rate is 10-11 cm/year. The intercept values calculations show that at least 12 silicate nuclei at the same time was formed, at the chamber.

The Seranjic skarn occurs as invading of Late Jurassic intrusive body with granite composition within impure carbonate rocks. Field observation and mineralogical investigations show the exoskarn is the most widespread skarn in the Seranjic skarn and is mostly calcic skarn together with magnesium skarn as a narrow marginal zone. The mineral assemblages indicate two stages of evolutions: the prograde and the retrograde stages. The prograde stage is characterized by garnet and clinopyroxene. The texture evidences and EPMA chemical analysis of clinopyroxene and garnet show two types of clinopyroxene and three types of garnet in various zones during the prograde skarn. Type 1 clinopyroxene show salitic (Hd27-40 Di58-51 Jo8-14) and ferrosalitic (Hd58-75 Di27-16 Jo8-13) compositions in the forsterite-clinopyroxene and garnet-vesuvianite-clinopyroxene zones respectively. Type 2 clinopyroxene has the intermediate compositions of salitic and ferrosalitic (Hd36-48 Di43-51 Jo7-12) in the garnet-vesuvianite-clinopyroxene zone, which is accompanied by scheelite crystallization. Garnet mostly occurred in the center near the exoskarn zones to the plutonic body. Type 1 garnet is characterized by grossular-rich granditic composition (Grs65 And25 to Grs45 And40) with pyralspite< 10 mol percent, and the textural evidences show coexisting type 1 garnet and type 1 clinopyroxene that is widespread in the garnet-vesuvianite-clinopyroxene zone. Type 2 garnet (Grs50 And25 Pyr25 to Grs45 And20 Pyr35) and type 3 garnet (Grs70 Pyr30 to Grs60 Pyr40) have the highly pyralspite and occurs as proximal zones from the plutonic bodies. Based on mineral assemblages, the formation of type 1 garnet, comparative to type 2 and type 3 garnet, is in more oxidized condition in the distal zones of the skarn. Moreover, garnet/clinopyroxene ratios observed at the skarn is affected by the F high volume of magma-fluid. Also, the abundance of F in the volatile phase is probably largely responsible for the abundance of F-bearing minerals, such as vesuvianite, and the scarcity of pyroxene in the skarn. Composition of the variation types of clinopyroxene and garnet show the prograde skarn can be stable at relatively oxidized to relatively reduced and LogfO2 =-18 to-30.

The Esfezar bentonite deposit is located 50 km east of Birjand, in south Khorasan Province and as a part of eastern boundary of lut Block. This deposit is a diagenetic bentonite type, because of its layering, existence of gypsum between bentonite layers, and expanded shape. Petrography and chemical analysis of host rocks in Esfezar bentonite deposit indicate that they are mainly of dacite and trachyandesite. X ray diffraction analysis shows that the main minerals of Esfezar bentonite deposit are Na-montmorilonite, Ca-Na montmorilonite, plagioclase, cristobalit, gypsum, illite, K feldspar and quartz. The loss and gain diagrams of bentonites compare with their volcanic host rocks show that the elements of Na, K, Ca and Al are lost, while the Si, Fe, Mg, Ti and S elements are gained. The lithophile elements such as Rb, Cs and Ba similar to K in bentonite samples are lost. Sr, as the same as Ca, has gained. Elements such as Cu, Ni, Cr, V and Ti, because of surface adsorption of montmorilonite, have increased and vanadium show more enrichment than other elements. REE pattern in bentonite samples from Esfezar deposit and host rocks are similar and LREE are more than HREE. It might be possible some reaction happened between volcanic rocks or glass with sea water resulting rapid coolness which results some elements such as Ca, Al, K, Na cleared, volcanic glasses are altered and bentonite formed by receiving Mg and Fe from sea water. Existing of silicon in that environment causes opal and crystobalite to be formed.

Nodushan Zn-Pb deposit at the western margin of Urumieh-Dokhtar volcano-plutonic belt resulted from granitoid intrusion into Eocene dacitic to andesitic rocks. Pyrite, sphalerite, galena and chalcopyrite are the main sulfide minerals. The chemical composition of sphalerites and pyrites indicates two different type of sphalerite (high Fe types demonstrating chalcopyrite disease and low Fe type) and two different types of pyrite (high As and low As), but weaker chemical changes can be traced from margins to center of galena and chalcopyrite. These chemical changes demonstrated that the hydrothermal fluid was high in iron, manganese, zinc and cadmium content (with the development of pyrite and sphalerite), followed by arsenic and lead concentration (with the development of galena, chalcopyrite and high As pyrite), indicating higher chemical composition changes at the incipent stage of mineralization than later stages. Chemical composition of sphalerites and its comparison with sphalerites in hydrothermal and skarn deposits of Japan confirming (high sulfidation) hydrothermal vein type mineralization resulted from magnetitic-type granitoids.

The chromitite ores of Sabzevar ophiolitic zone could be divided into two groups of high Cr and high Al. The concentration of Cr2O3, As, S and some heavy metals (Cu, Ni, Ag, Co, Zn) is higher in high Cr samples; while high Al chromitites show higher concentration of Al2O3, SiO2, TiO2 and other trace elements. The high Cr chromitites have higher PGE than Al-rich samples and PGE concentration increases with Cr2O3. The high Cr chromitites have fractionated PGE chondrite-normalized patterns with negative slope (Pd/Ir = 0. 25) and high IPGE/PPGE (average 6. 22); while high Al chromitites show unfractionated and relatively flat patterns (Pd/Ir = 1. 9, IPGE/PPGE = 2. 88). The PGE composition of high Cr chromitites indicates they are formed by high degrees of partial melting (boninitic melt) in arc setting. In contrast, Al-enriched samples have been produced by low degrees of partial melting (toleiitic melt) beneath spreading centers (i. e., mid-ocean ridges or back-arc basins). The results of PGE composition of Sabzevar chromitites are coincident with chemical composition data of chromite crystals in these samples.

The Mamzar granitoid pluton is located in the Kerman Province and structurally in southeast of Urumieh-Dokhtar magmatic zone. Based on petrographic studies, the granitoid consist of four rock type of diorite, tonalite, granodiorite and monzogranite. They are mainly composed of plagioclase (andesine), alkali-feldspar (orthoclase), quartz, amphibole (magnesiohornblende), biotite and clinopyroxene. Mineral chemistry of plagioclase indicate that their composition are andesine with An33-47 and the amphibole (calcic) have magnesiohornblende compositions that is feature of I-type granite. The biotites with Fe/ (Fe+Mg)>0. 33 are magnesio-biotites. Based on TiO2 versus Al2O3 diagram, composition of amphiboles indicate crust and mantle mixing in the formation of the Mamzar granitoid magma. Application of different barometers and thermometers such as Al-in-hornblende, plagioclase-amphibole pair exhibit an average pressure of 1. 14 kbar and temperatures of 660-730 ° C for the intrusion. The mineral chemistry of the biotites and amphiboles indicate that this granitoid pluton is calc-alkaline and formed at the depth of less than 8 km.

The intrusion of Boroujerd Granitoid Complex into the metamorphosed pelitic rocks has resulted in the formation of pelitic hornfelses and anatectic migmatites in its metamorphic aureole. The effective melting reactions include fluid-present and fluid-absent. Fluid-present melting reactions may have consumed the whole free fluid in the aureole as a result of which melting process continued through fluid-absent reactions. It is highly probable that high-grade mineral assemblages like spinel+corundum in the aureole have formed by biotite dehydration reactions. As a result, the presence of spinel and corundum minerals in these rocks is related to the fluid-absent partial melting. Using thermodynamic equilibrium of minerals and multiple equilibrium reactions, peak pressure and temperature of metamorphism are estimated as 4 kbar and 750 ° C respectively. The total fluid activity in melanosome cordierites (a CO2 [0. 15] + a H2O [0. 6]) is 0. 75 at the aforementioned pressure and temperature. Melt-water content in Boroujerd migmatites is 3. 75 % and H2O content of cordierite in melanosomes is 1. 1 %. Considering these numbers, the Dw of melt reactions at 750 ° C for Boroujerd migmatites is 3. 41 % that correlates with biotite dehydration reactions. The H2O content of melts matches the minimum water line which is representative of fluid-absent conditions and confirms the correctness of petrographical studies, fluid-absent reactions and the estimated Dw in migmatites.

The Almaghoulagh antiform in north of Asadabad, Hamedan, is one of the areas where the Paleozoic rocks are exposed in the Sanandaj-Sirjan zone. The antiform comprises two metamorphosed units. The Almaghoulagh unit in the lower part is overlain by the Chenar Sheikh unit, whereas the former derived from a volcanic protolith, the latter had a protolith with a significant sedimentary component. The Late Jurassic and Early Cretaceous felsic and mafic plutonic bodies are situated in the core of the antiform. The S1 foliation, which can be recognized throughout all the lithological units, is considered to formed during a regional metamorphic event. The amphibole-plagioclase thermometer and amphibole-garnet-plagioclase-quartz barometer yielded metamorphic temperature of 570° C and an average pressure of 7. 2 kbar for the Almaghoulagh metabasites. The P-T condition of metamorphism in the Chenar sheikh metapelites was also estimated at 462° C and an average pressure of 2. 6 kbar using the biotite-garnet thermometer and garnet-plagioclase-biotite-muscovite-quartz and garnet-plagioclase-muscovite-quartz barometers. These P-T estimations suggest that the regional metamorphism reached the amphibolite grade and the lower part of the Almaghoulah antiform experienced a higher degree of metamorphism. The S2 foliation, which is the most penetrative structural element of all the rock units in the region, formed within a shear zone. Occurrence of the shear stress in the region, facilitated intrusion of the Late Jurassic and Early Cretaceous plutonic bodies into the core of the antiform. The emplacement of the plutonic bodies has played a major role in folding and doming the region.

The clinopyroxene composition of two types of alkaline and calc-alkaline gabbros at Piranshahr pluton was investigated in this study. The major oxides variations are similar in all clinopyroxenes of two types of gabbros and are classified as diopside-augite; but trace element compositions are very different in these two groups. The clinopyroxenes of alkaline gabbros are rich in high field strength elements (HFSE) and rare earth elements (Σ REE= 34-64 ppm) and have high 87Sr/86Sr ratios. In other side, the clinopyroxenes in calc-alkaline samples have high Sr, Rb and Ba and elevated 87Sr/86Sr; but are depleted in HFSE and rare earth elements (Σ REE= 9. 4-21. 6 ppm). Calculation of equilibrated melts from trace elements composition of clinopyroxenes using partition coefficients between clinopyroxene and the basaltic melt show that they are formed by different sources which is consistent with whole-rock geochemical data of gabbros.

The studied area, as Ykeh-Chah unit, is a part of Golpayegan magmatic and metamorphic complex in Sanandaj-Sirjan structural zone. The unit consists of mylonitized and high-grade metamorphic rocks, including biotite-gneiss, biotite-garnet-gneiss, amphibolite and orthogneiss. The biotite gneiss and the biotite garnet gneiss have partly been migmatitized. They show various structures such as stromatic, ptygmatic, folded, ophthalmitic, net like, and patchy. Leucosomes are as in-situ and vein leucosomes. According to the leucosome type and some preserved igneous microstructures in leucosome, partial melting of metasedimentary units have been the dominant process in the generation of the migmatites. The most reliable microstructural criterion, as the evidences of partial melting in the migmatites, are simple twinning in K-feldspar, corroded biotite, plagioclase with zoning, melt presence, symplectic replacement aggregates in leucosome and mesosome, muscovitization some of the minerals. Due to the presence of leucosome and migmatization process, the rocks have been undergone the prograde metamorphism at the increasing temperatures until the partial melting, and finally experienced retrograde metamorphism during cooling. Evidence of the retrograde metamorphism in the rocks include the emplacement of rutile by titanite and ilmenite, symplectite texture (quartz + muscovite), myrmekite texture (quartz + plagioclase), atoll garnet, alteration of garnet to quartz and chlorite.

The Majerad metamorphic complex is located in the northern margin of the Central Iran structural zone and southeast of Shahrood, includes a wide variety of metacarbonate, metabasite (greenschist, amphibolite and garnet amphibolite), metapelite, metapsammite and metarhyolite. The protolith of metabasites has been submarine basaltic lava flows which erupted in the Late Neoproterozoic intracontinental extensional basins. Magma forming of the protoliths of metabasites had alkaline nature, enriched in LILEs and LREEs, depleted in HFSEs and HREEs and originated from OIB to EMORB source regions. With respect to the results of U-Pb age dating on extracted zircons from granitoids which cut this complex (553 ± 3. 8 million years), Majerad complex has Late Neoproterozoic age. According to the carried out studies, it can be state that the mentioned basins often didn’ t reach the stage of the oceanic lithosphere formation, and then due to the dominance of the compressional regime, these basins rapidly closed and the contributed rocks in these processes, obducted in the form of accretion prisms on the continental plates and probably progressed up to the continental-continental collision.

Tertiary acidic to intermediate volcanic activities and the role of fault zones in Sarbisheh area have provided suitable conditions for the formation of bentonite, especially in pyroclastic deposits. Southeast Gondakan, Kalateh Pedaran, Golab, Golestan, Asfich, Hasan Kolangi, and Kangan bentonites in 1/100000 geological map of Sarbisheh were selected as the case study. Satellite image processing shows argillic alteration with the presence of montmorillonite. Field and XRD studies approved satellite image processing and bentonite formation in the studied areas. Montmorillonite, anorthite, and cristobalite are the main minerals in these bentonites. Based on available data, Hasan Kolangi, Asfich and Golestan bentonites are Na-Ca, Ca-Na, and Ca-type respectively. Parental rocks of studied bentonites are acidic to intermediate lavas (rhyodacite-dacite to andesite) and pyroclastic rocks (tuff-breccia) that had affected by medium to high-grade alteration. Calculation of geochemical changes in bentonitic zones indicated the decrease of silica, Na, and K and increase of Ca.

Extension of the optical response with the high efficiency in visible region of the solar light spectrum is one of the research goals of the photocatalysts based on TiO2. In this work, Cr doped TiO2 was synthesized by sol-gel method at different annealing temperature of 400, 600 and 800 oC in order to increase the optical absorption of TiO2. Upon increasing the annealing temperature, the anatase transformed to rutile while the size of the nanoparticles increased. Anatase was often used for investigation of photocatalytic activities and has been introduced as the desired phase of TiO2 for the photocatalytic applications. According to the observed increase in the optical absorption of the rutile by diffuse reflectance spectroscopy (DRS) and considering the structural properties of rutile, this phase of TiO2 can also be considered for photocatalytic activities and applications.

The CH3NH3PbI3 is one of the most widely used and famous lead halide perovskite absorber layer for using in perovskite solar cells. One of the ways to deal with the instability problem of this perovskite structure in environmental condition is bromide doping in this composition. In this work, the structural and optical properties of the bromide doped CH3NH3PbI3 absorber layers were studied as well as J-V characteristics of solar cell devices based on this absorber layer were also measured and analyzed. Photovoltaic parameters of the fabricated solar cell were measured continuously for 162 days. The results of this study showed that even though the bromide-free perovskite devices has the highest PCE (11. 65%), but suffer from a significant drop in PCE (86%) during the measured time period. Comparison of the results showed that the lowest rate of efficiency loss (1%) was obtained for the solar cell with a 1: 1 molar iodine-bromide ratio with an energy conversion efficiency of 9%.

In this research, the SrMnxFe12-xO19 nanoparticles with x = 0. 0, 0. 5, 1, 1. 5 and 2 at 1000 oC for 4 h, using sol-gel method, were synthesized. Thermal analysis, crystalline structure and their bonding properties of the samples by TGA / DTA analysis, XRD and FT-IR were investigated. In order to investigate morphology of the samples from field emission, scanning electron microscopy (FESEM) was used. Also, properties of the samples, using vibrating sample magnetometer (VSM), were investigated. In addition to the Curie temperature of SrMnxFe12-xO19 nanoparticles with x = 0. 0, 0. 5 and 1 was determined. Thermalgravimetric analysis confirms that the formation of the hexagonal phase at temperature of 953. 1 oC. The results of measurements of the XRD show that the phase percentage of SrMnxFe12-xO19 nanoparticles with x = 0. 5 has increased. The results of the hysteresis loops of SrMnxFe12-xO19 nanoparticles reveal that with increasing Mn contents, the saturation magnetization, remanence magnetization and magnetic coercivity reduced. Also, the results of the magnetization of SrMnxFe12-xO19 nanoparticles with temperature reveal that with increasing of Mn contents, the Curie temperature decreased.

Twinning is one of the main mechanisms of plastic deformation in crystals and its effect on the empirical properties has been important in materials science. Twin boundaries have been proved to be effective flux pinning centers in YBCO that increasing the critical current density. High-temperature superconductor YBa2Cu3O7-x (YBCO) nanoparticles were prepared by solid state alloying method. The phase formation and microstructure of the bulk and nano powders of YBCO were studied, using Rietveld refinement and Williamson– Hall (W– H) analysis. We estimated the critical length scale around 250 nm when it will be still energetic to create twins instead of remaining elastically strained and twin less. The synthesis YBCO powder has very small grains with the size about a few (30-40) nano meters. The microstructure analysis shows that the obtained YBCO powders have very fine grains with a size around several tens of nanometers. Twin boundaries did not observe in YBCO nanocrystalites. Therefore, designing of twin microstructure and effective control of the particles size in YBCO, has an effect directly on the critical current density of the samples that are important for its commercial exploitation.