Hematite

Hematite (Fe₂O₃) is used as a mild abrasive in friction materials (Mohs hardness 5.5-6.5) and as a red pigment for the underlayer of disc brake pads. Furthermore, it can be used to improve the thermal and electrical conductivity of the friction material, the latter being helpful in case the brake pads run through a corona-style powder coating process (especially in case of NAO formulations).