Micronized perlite filler product, methods of producing the micronized expanded perlite products, and methods of use thereof are provided. The micronized expanded perlite product has, for example, a small median particle size (for example, less than 11 microns), a high blue light brightness (for example, higher than 84) and low oil absorption (for example, less than 70 percent in volume). The micronized expanded perlite product may be used in a variety of applications such as anti-block filler in plastic films and reinforcement filler in polymers.