Bronze and brass ornamental work a smaller or greater amount of zinc. In early times this metal seems to have been sparingly employed, but from the Middle Ages onward the industry in brass was a very important one, carried out on a vast scale and applied in widely different directions. The term "latten", which is frequently met with in old documents, is rather loosely employed, and is sometimes used for objects made of bronze; its true application is to the alloy we call brass. In Europe its use for artistic purposes centered largely in the region of the Meuse valley in south-east Belgium, together with
Native metal more reactive than gold. Natural alloys of the platinum group metals include: native osmium (Os,Ir,Ru), rutheniridosmine (Ir,Os,Ru), ruthenium (Ru,Ir), palladium (Pd,Pt), platinum Pt, and rhodium (Rh,Pt). In addition gold, copper, iron, mercury, tin and lead may occur in alloys of this group. As with gold, salts and other compounds of the platinum group metals are rare; native platinum and related metals and alloys are the predominant minerals bearing these metals. These metals occur associated with ultramafic intrusions and placer deposits derived from those intrusions. Native copper has been historically mined as an early source of the metal. The term Old