Clintonite, a rare sheet silicate mineral, was found to be associated with monticellite, aluminodiopside and spinet in magaesio-alumino-skarn of several iron deposits in Handan-Xingtai area, Hebei Province. It is dark green in color and occurs as pseudohexagoaal tabular euhedral crystals. Its chemical compqsi- tion varies accord with the isomorphous substitution R(2+)M+Si(N)→R3+(M)+Al ClintonEite has three polytypes, namely 1 M,3 T.and Md, with 3 T being detected for the first time in native clintonite. Mossbauer spectral studies reveal that there exists Fe3+ in tetrahedral coordination of the crystal structure. Infra- red spectra of clintonites only show very limited variation. The 3730cm-1 and 3615 cm-1 OH streteching bands correspond to the Mg-Mg-Mg and the Mg- Mg-A1 octahedral composition respectively. The structure of clintonite is partly damaged at 10000℃ and completely destroyed at 1050℃，leading to the formation of bees phase spinet and some other minerals. Clintonite was foimed in an Al- rich, SiO2-poor and relatively high-temperature environment.