The Guangfu porcelain stone deposit is of gigantic size, and the porcelain stone consists mainly of fine-grained quartz (making up some 62%)and seri- cite (about 36%).It is noted for rich potassium, high silicon, poor aluminium and low iron in chemical composition and shows quincuncial texture typica- lity of porcelain stone from China. The sericite in the porcelain stone belongs to dioctahedral type with polytypa being 2M:and unit cell parameters being a=5.15A，b=8.97A，c=20.10A and β=96.18°.It is characterized by high crystallinity and low degree of hydration. The approximate equality of the peak width W1 and W2 of basal reflection 10A and 5A suggests that sericite in Guangfu porcelain stone does not contain montmorillonite (interlayer) minerals. According to characteristics of values of d(060) and 530cm-1 frequ- ency band, there are almost no such harmful impurities as iron and magnesium in octahedra of the sericite. The chemical formula of seriCite is (K0.809Nao.o37 Cao.oo3)o.849(Al2.083Feo.oo6Mgo.o75 )2.164[(Si3.272Alo.728)4O10] (OH)2.It is therefore concluded that Guangfu porcelain stone is excellent in quality and will serve as a kind of good raw materials for ceramic production.