that the compact has a relatively high coefficient of thermal conductivity i e of the order of 100 wm 1 k 1 because the substrate has a coefficient of thermal conductivity substantially less than that of the cubic boron nitride compact the heat will be dissipated only slowly through the substrate and tend to concentrate in the thin compact this it has surprisingly been found improves the abrading performance of the compact in the prior art cubic boron nitride compacts having intergrowth between the cubic boron nitride particles have been bonded either directly to a metal tool or to a cemented carbide substrate both such substrates have high coefficients of thermal conductivity and of the same order as that of the cubic boron nitride compact the improvement in the abrading performance of the compact in the abrasive body of the invention over such prior art bodies is particularly surprising as it has always been believed that heat generated in the compact should be removed from the compact as quickly as possible to minimise any degradation of the cubic boron nitride particles occurring the substrate will generally be larger in mass than the compact and should have good mechanical strength and a coefficient of thermal expansion close to that of the compact examples of suitable materials for the substrate are oxides nitrides and syalon a commercially available silicon aluminium nitrogen oxygen ceramic examples of suitable nitrides are boron nitride aluminium nitride and silicon nitride examples of suitable oxides.