A blast cleaning abrasive made from slag produced by metal-smelting operations or by coal-fired boilers and power plants. Most slags are processed by quenching in water, crushing when necessary, washing, and screening to produce an acceptable abrasive. Slag abrasive manufactured by an air-cooling process has a different mineral structure. The quality and durability of the abrasive depends upon the processing and can vary widely from batch to batch and from source to source. Typical slag abrasives include copper and nickel slag from metal smelting and coal slag from electric power generation.