20 MICRONS MICA is a Muscovite Mica, because of its crystal structure and chemistry, has proven to be a very useful additive in a broad range of industrial and technological application. Dry-ground Mica is processed in Attrition Mills and plans are underway to produced Wet-ground Mica in Muller Mills. The platy structure of Mica particle and its high aspect ratio lead to superior coverage, mainly through platelet alignment and overlapping.