The article shows the relationship between the iron ion content of the flotation pulp and the selectivity of mica flotation of a granitic pegmatite from Limbergsbo, Sweden which contains 40% albite, 20% microcline, 30-35% quartz and 4% muscovite. The results of comparative experiments involving flotation in stainless steel and iron-rich environments show that selectivity with respect to microcline and quartz is better when an iron mill is used for grinding.