In chemistry or mining, polymetal or polymetallic is a substance composed of a combination of different metals. When the substance contains only two metals the term bimetal (bimetallic) is sometimes preferred. A polymetallic ore (or polymetal ore) is an ore that is the source of more than one metal suitable for recovery. A mine containing polymetallic ore is a polymetallic mine. Polymetallic nodules are concretions of manganese and iron (and other metals) found on the ocean floor. They are sometimes called manganese nodules, after their principal component.