SYNTHETIC FLUORPHLOGOPITE

A reported manufacturing method of synthetic fluorphlogopite designed for industrial scale batches involved melting oxide–fluoride mixtures (metal, i.e., aluminum and manganese) at a given “soak” temperature (wherein the contents are liquid; up to 1,450°C) and then cooling at a continuous rate of a few degrees per hour between 1,400°C and 1,300°C. This technique produced large fluorphlogopite monocrystals (several centimeters). An alternate method synthesized fluorphlogopite single crystals, several millimeters in size, suited to laboratory uses. A mixture of SiO₂, γ-Al₂O₂, MgO, and K₂SiF₆ was melted at 1,450°C for 3 hours, cooled to 1,385°C at a rate of 100°C/h, and then quenched into cold water. The resulting charge was loaded back into the furnace, heated from ∼1,000°C to 1,385°C at a rate of 500°C/h, and finally cooled at a rate of 1°C/h down to 1,300°C. This procedure led to the formation of large and detachable monocrystals of synthetic fluorphlogopite up to 1 cm in diameter.

The Cosmetic Ingredient Review Expert Panel (the Panel) reviewed the safety of synthetic fluorphlogopite as used in cosmetics and concluded that it was safe as cosmetic ingredients in the practices of use and concentration as given in its safety assessment.