Geology, mineralogy, and chemistry of skarn zones and orebody in Ma’danjoo iron skarn prospect area, east of Sangan mine, Khaf, NE Iran

The Ma’danjoo prospect area is one of the eastern anomalies of Khaf’s Sangan iron mine in southeast of Mashhad. Geological units in the area include Jurassic sedimentary rocks, skarn, and Tertiary subvolcanic intrusion with monzonitic composition. Skarns have been seprated  in to 7 zones on the basis of abundance and type of the calc-silicate including: garnet, pyroxene-garnet, pyroxene, phlogopite, epidote, chlorite-epidote, and epidote-chlorite skarns. Magnetite and sulfide mineralization were occurred in low temperature phlogopite and epidote skarns. According to electron probe micro analysis (EPMA), the compositions of garnets and pyroxenes are andradite-grossular and hedenbergite to hedenbergite-diopside, respectively. Mineralization at the Ma’danjoo prospect area formed as stratiform and massive bodies in the carbonate rocks. The main ore mineral is euhedral magnetite (40%) with minor amounts of pyrite, pyrrhotite, chalcopyrite, melnikovite, specularite, and pyrolusite. Secondary minerals are hematite and psilomelane. The FeO in the magnetite changes from 84% to 91% and the S content is below 2%. The magnetites are high in Mg (over one percent). Contents of Ni, Cr, V, Ti, Ca, Al and Mn in the magnetite indicate that these magnetites are skarn type. The Ma’danjoo magnesian skarn has some similarities with other magnesian skarns in the Sangan mine especially Dardvey area due to the presence of diopside, phlogopite, termolite and high-Mg magnetite.