Abstract: The environment of mineral preservation was indificated by the mineral component of the metamorphic. The graphite came from muddy sediments which formed by metamorphism according to the mineral assembled, especially the graphite, cordierite and garnet in the second iron ore of Gongchangling. By the calculation of physical chemistry, the iron oxide can form hematite under the conditions of pure water while it can form magnetite under the conditions of graphite. The activity of the O2 which comes from H2O is very low by the relation of hematite and magnetite. The results can be used to explain the appearance of "two sides are large, the intergrade is small" and the appearance of the martite which is undergroud 500 m.