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The Senjedeh gold deposit is situated 60 km southwest of Delijan in the central section of Sanandaj-Sirjan metamorphic belt. Most of rocks in this region have undergone greenschist to lower amphibolite metamorphism. The gold mineralization in the study area occurs as quartz sulfide veins in metarhyolite host rock. In order to detect the abundance of gold and associated elements in the pyrite using the techniques of mineralogical studies, electron probe microanalysis (EPMA) and back-scattered imaging through thin and polished sections in the Senjedeh gold deposit. Two generations of pyrite recognised: first generation, being anhedral to subhedral, (G1) are oriented along foliation contain high to medium gold content(up to 810ppm), shows deformed and fractured character. The second generation of pyrite (G2) is euhedral with medium to low gold content (below limit of detection up to 110ppm). According to electron back-scattered image and EPMA data, the presence of gold mainly occurs as submicroscopic-microscopic inclusions and invisible particles in microfractures of pyrite. Also based on EPMA mapping it is concluded that first-generation of pyrites contain high level of cobalt which could be a good indication of the presence of mafic and ultramafic rocks as a source of hydrothermal solutions compared to felsic rocks and consistent with orogenic gold deposit. [ABSTRACT FROM AUTHOR]

The article presents a study which focuses on the distribution of rare earth element (REE) during diagenetic processes of sedimentary copper (Cu) deposit in Nahand-Ivand Area, Northwest Iran. Topics discussed include a table showing geochemistry of different type of sandstone in the Area such as red, gray and oxidised sandstone; relationship between Cu and REE contents in sandtone and characterization of REE patterns of sandstone by a negative to positive Europium (Eu) anomaly.

The article presents a study conducted to investigate the gold distribution patterns in pyrite from the Senjedeh gold deposit located in Muteh Mining District, Iran. Topics discussed include the investigation of pyrite using combination of ore microscopy such as electron probe microanalysis and back-scattered imaging, influence of deformation on the distribution of gold in pyrite and microscopic and field observations depicting two generations of pyrite, first generation and second generation.

Copper mineralization in Nahand-Ivand area, NW Iran, appears as disseminated copper sulfides along a redox boundary between gray sandstone and microconglomerate and hematitic sandstones, siltstones and shaly marl. Geochemical analyses of the Nahand-Ivand deposits show as much 35 wt.% Cu and 730 ppm Ag in the gray sandstone. Electron probe micro-analysis (EPMA) was used to determine the mineralogical composition and distribution patterns of copper and silver-bearing phases mainly in pyrite and Cu-bearing sulfides. The EPMA data were essential for evaluating the distribution and partitioning of potential economically-valuable components between co-existing minerals. Furthermore, they contribute to a better understanding of the genesis of the Nahand­Ivand copper deposits and will guide further exploration in the region. The EPMA results from different types of pyrite reveal Cu contents as high as 0.32 wt.%, 1.10 wt.%, and 2.88 wt.% for framboidal pyrite (PyI), overgrowths on framboidal pyrite (PyII), and diagenetic pyrite (PyIII), respectively. This successive increase of copper from PyI to PyIII is attributed to a continuous supply of copper that replaces framboidal pyrite in turn by the more copper-rich digenetic pyrite. Because of hydrothermal overprinting, pyrite has been replaced by djurleite, roxbyite, and other nonstoichiometric Cu–S minerals that include covellite. The EPMA study indicates that covellite contains significant concentrations of Ag (locally > 1 wt.%). In contrast. only trace amounts of silver have been detected in pyrite and other copper sulfides, indicating that covellite is the major Ag-carrier in the ore. According to textural relationships, such open space filling, impregnation, and replacement textures, and the EPMA results, later stage copper-bearing fluids were responsible for the silver enrichment in the Nahand-Ivand deposits. [ABSTRACT FROM AUTHOR]