This Bureau of Mines investigation studied the effect of thermal treatments upon concentratability of a Western Mesabi Range nonmagnetic taconite ore and is a sequel to Bureau of Mines ri 7567. Magnetic tube tests were used to develop the data needed to calculate separation efficiency, the primary measure of concentratability. A horizontal tube furnace was employed to heat treat and reduce the hematitic ore samples. The two variables studied were roasting temperature and cooling method. The manner of cooling, either by slow cooling or quenching in water, produced no significant difference in concentratability. Roasting temperatures employed ranged from 500 deg to 1,000 deg c, and a temperature of 650 deg c effected the best concentratability. The temperature of 650 deg c correlated with the most effective roasting temperature for grindability.