This paper analyses the geological features and metallogenic regularities of the old mining district in Gejiu．Contact metasomatic deposits are closely related to skarns in depressions and protrusions of granite bodies．Stratiform deposits are controlled by intraformational faulting． Primary deposits include： 1．crevice— vein—infilling mineralization in clastic rocks；2．pneumato- hydrothermal stratiform ，vein and stockwork deposits inlimestones and dolomites， and 3． contact- metasomatic deposits in skarns． Hydrothermal activities andhydrothermal alterations are prom inent in this mining district． Hydrothermal alterations in granitic rocksinclude carbonatization， chloritization， greisenization， serl—cltl。Zatl。on and albitization． Carbonatization andgreisenization are closely related to Sn—W mineralization．Presented in this paper are major element data forvariant hydrothermal alteration granitic rocks in Gejiu．Different types of granite can be distinguished on thebasis of significant differences in major element associations．Prospecting targets for Sn-Cu- polymetallicmineralization in the east and west of the Gejiu mining district are also discussed in this paper．