I. INTRODUCTIONIn July, 1946, while investigating the pyrite deposit ot Peyinchang, Kaolan,. Kansu [7], the writer noticed that the country rocks of the deposit, formerly recognized as a series of metamorphosed sedimentary rocks consisting mainly of phyllite, quartzite and schist by Mr. P. Chen [2], and Messrs. N. L. Liu, W. Y. Liang and T. C. Liu [4] who visited there in the years of 1940 and 1944 respectively, are far different in rock character as compared with the doubtless metamorphosed sedimentogenous rocks over-