The phenomena of interstratification(mixed layer)have been consideredas special structural phenomena in silicates since they were recognized. The-refore,interstratified minerals,whose basic structure sheets(BAS)belong tothe subclaee of layer silicate,have been classified into the category of clayminerals. However,there exists another kind of interstratified minerals whoseBAS belong to more than one class(such as sulfides,chlorides,hydroxides,carbonates and silicates).In order to compare with the traditional intersta-tified minerals,we propose a new concept-interstratified mineral with basicstwcture sheets of different classes,and restrict this concept within five res-pects from the structure and composition of BAS to the stocking regularityof BAS. Valleriite,a typical interstratified mineral with basic structure sheets ofdifferent classes,is also studied in this paper. Electron microprobe analysesindicate that the degree of mismatch between sulfide layer and hydroxidelayer is higher,the results of X-ray analyses show clearly the diffractionsfrom d001 to d007,and repetition interval of 11,45A,The studies by means ofhigh resolution transmission electron microscopy also reveal the lattice fringeimage of 11.4A in c-direction,and disorder in a-and b-directions, o there isno supercell in valleriite,and this differs from the view held by H.T. Evans(1968)that valleriite is a mineral with supercell with c= 34.10A and a=64.46A.