Characterization of Weathering Process in Biotite Gneiss and Granite, Ganghwa Island

X-ray diffaction and chemical analysis were used for mineralogical characteristics of weathering grade of granite and biotite gneiss. Granite is composed mainly of quartz, albite, and minor K-feldspar and biotite gneiss is biotite, quartz, albite. Illite and kaolinite increased in granite, and vermiculite and halloysite in biotite gneiss as increasing weathering process. The percentages of increase but that of CaO, decrease as the weathering process. different from granite and biotite gneiss.