The newer high chromium-molybdenum alloy irons bridge the gap between the extremely tough Hadfield's manganese steels which have relatively poor abrasion resistance and the nickel-chromium martensitic irons which have excellent abrasion resistance but are too brittle for many mining applications. The article gives a brief history of high-chromium alloy irons, discusses the development of high chromium-molybdenum irons, and describes some applications, such as for abrasion-resistant pumps, ball mills, autogenous and semiautogenous mills, and rod mills.