Mineral chemistry of pyrite by EPMA mapping from the Senjedeh Gold deposit, Iran
Keywords:
Pyrite, EPMA, Senjedeh, Gold, Mineral chemistryAbstract
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.
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