SWELLABLE SYNTHETIC FLUORINE MICA

PROBLEM TO BE SOLVED: To obtain a swellable fluorine mica maintaining excellent cation exchangeability and swellability even after being exposed to a high temp. to reduce holes by composing it of a chemical composition coordinating Na ions in the holes in octahedral layers in the crystal structure of Na type sellable fluorine mica. SOLUTION: Silica, magnesia, magnesium fluoride, sodium silicofluoride, sodium fluoride, sodium carbonate and tale or the like, are prepd. as starting materials so as to be the chemical compsn, of objective swellable fluorine mica represented by the formula Na(Mg2.5-0.5x Nax Si4 O10 F2 (where, an x value is 1>=x>0, preferably 1>=x>=0.10). After they are melted at 1,400-1,500 deg.C in an internal combustion type electric furnace, the resultant molten material is cast into a mold and cooled to synthesize the objective swellable fluorine mica. This synthetic fluorine mica has >= 30 ml/2 g swellability and >=60 meq/100 g ion exchange quantity after being heat-treated.