Detailed investigations into typomorphic characteristics of chemical composition of chrome micas from gold deposits of Jiaojia type in Jiaodong area show that high contents of Cr,Ni,V,Ti,Mg and Fe in octahedral sites and Si in tetrahedral sites and low content of K in interlavers of chrome micas were all in favour of hydrothermal alteration and gave rise to,gold mineralization.The association of chrome micas formed at the main oreforming stage with electrum,pyrite,ankerite and quartz in orebodides serves as a good indicator of the precipitation of gold from auriferous hydrothermal fluids. Sericite formed at the early oreforming stage is widely distributed in altered rocks;muscovite formed at the late transitional(diagenetic-metallogenetic)stage is obsorved near orebodies.The complete evolution from muse vite through sericite to chrome micas existed in the new subgroup of Cr-Al series which had been developed on the basis of the subgroup of Al series known nas muscovite in natural mica.and this also finds expression in the reduction of grain size,decrease of K content and increase of H2O content in interlayers,and increase of Si in tetrahedral sites and Cr,Ni,V,Ti,Mg and Fe in octahedral sites, indicating strong hydrothermal alteration and intense,gold mineralization. The uniform, persistent and continued mineralization in the same Jiaojia type gold deposit suggests the continuity and completeness from the rock-forming process to the ore-forming process.