|Abstract:Abstract: The mineral geological survey was conducted in the Southern Beishan Mountain to ascertain its types and distribution. The Manganese-rich ore bed has bee discovered in quartz schist in Changchengian System stratum. In the field , it is 0.5m thick in the surface, yet 4.6m extending in horizontal direction owning the bean shape. Its upside is Mn-limestone and Mn-magnetite quartz rock, sandwiched between Quartz schist. The manganese ore is black, bulk, semi- metallic luster, also dirty hands. The results of the manganese ore samples by quantitative chemical analysis, are Mn 29.68%、30.59%、27.72%，Mn/Fe 9.2、9.8、8.7，P/Mn 0.00071、0.00078、0.00076, the Mn of Mn-limestone is 4.62~4.92%，Mn-magnetite quartz rock is 0.52~1.54%. Moreover, based on the test of the phase analysis , the X-ray diffraction analysis, the electron probe, and the microscopic identify , the important minerals Rhodochrosite (MnCO3), Pyrolusite(MnO2), Manganite（MnO2?Mn(OH)2），Spessartine (Mn3Al2(SiO4)3) , Johannsenite(CaMn(SiO3)2) , Rhodonite ((Mn,Fe,Ca)5Si5O15), Tephroite(（Mn2SiO4）) , and some other minerals, have been determined perfectly well. It is much more instructive to compare our ore with many foreign Manganese ore, the characteristics of the Manganese ore and the assembling of the main minerals, strongly similaritied to the ore at the Paleoproterozoic Serra do Navio manganese deposit in Brazil and the Devonian metamorphosed manganese deposits of the South Urals and the Cretaceous Noda-Tamagawa Mine in Japan. According to the fieldwork, researching these special minerals and Mn content upside, We propose that the Mn-minerals ore had possibly deposited in the shallow-marine and marine environment around the Dunhuang ancient block edge areas. Manganese was come from the continent and the hydrothermal fluid sources relation to the magma beyond the sediment place. Then in period of regional metamorphism and contact metamorphism, sandstone had metamorphosed into quartz schist, the ores of Rhodochrosite and Pyrolusite and Manganite, as the primary high quality manganese ores, had become into Mn-silicate. After prolonged supergene weathering, the manganese ores we can see now, has been formed. The discovery of manganese-rich ores indicates that there is a metallogenic geological environment for the formation of manganese deposits in this area.