SEM-EDS analysis was conducted on lead flotation circuit products from three Cominco concentrators: Red Dog, Sullivan and Polaris, to clarify the influence of lattice-iron on sphalerite deportment. The iron content in sphalerite reporting to the lead concentrates was compared with the ore averages. There was a consistent and statistically significant difference in the iron content of the sphalerite in the feed and the sphalerite reporting to lead concentrate. Despite the differences in ore genesis and flow sheet, sphalerite misreporting to lead concentrates had a lower iron content than the sphalerite in the feed for all three concentrators.