The chemical and phase compositions of four different slags were studied with emphases on the form of Nickel, Cobalt and Copper. These were INCO slow cooled (IS), INCO fast cooled (IF), Falconbridge‐Sudbury fast cooled (FFS) and Falconbridge‐Timmins fast cooled (FFT) slags. The amount of each of Ni, Co and Cu in all the slags was less than 1%. IS contained the highest amount of Ni and Co of 0.57% and 0.21% respectively. The highest Cu content was found in FFS (0.87 %). The form of Co in all the slags was primarily oxide (> 98%). However, significant portions of Ni and Cu (20%) in IF and IS slag were in the sulphide form. Finer fractions (<270 mesh) of these slags were richer in sulphide forms of Ni and Cu (40%).