PURPOSE: To realize the superior water-proofness, heat resistance and mechanical strength by a silicone-mica laminated object of an amino-radical-contained alkoxi-silane compound and/or its hydrolytic decomposite and a defined epoxi- radical contained organic silicon compound on the surface of mica.

CONSTITUTION: A composite mica made of mica is treated by an amino-radical contained alkoxi-silane compound and/or its hydrolytic decomposite (A- constituent) and an epoxi-radical contained organic silicon compound (B- constituent) defined by Formula (I). The A-constituent is used at the ratio ranging 90W10wt.% and the B-constituent 10W90wt.%. The total quantity of A and B constituents on the surface of composite mica is usually defined in the range of 0.01W5wt.% of the composite mica (burned item equivalent weight). The organic solvent and others in the treating agent on the surface of mica are removed by heating and the layer, in which the A-constituent, the B- constituent and the reaction product of both constituents are mixed together, is formed on the surface of mica.