Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive, but sometimes with other elements such as phosphorus, manganese, aluminium, or silicon. It is hard and brittle, and it was particularly significant in antiquity, giving its name to the Bronze Age.
The Iguvine Tablets were a series of seven bronze tablets discovered at Iguvium, contemporary Gubbio, in Italy in the year 1444. They are also known as Eugubian tablets. The earliest tablets were probably written in the 3rd century BC in the native Umbrian alphabet, the latest in the 1st century BC in the Latin alphabet.
Bronze is the most popular metal for cast metal sculptures; a cast bronze sculpture is often called simply a "bronze". Common bronze alloys have the unusual and desirable property of expanding slightly just before they set, thus filling the finest details of a mold. Their strength and ductility (lack of brittleness) is an advantage when figures in action are to be created, especially when compared to various ceramic or stone materials (see marble sculpture for several examples).
Speculum metal is a mixture of around two-thirds copper and one-third tin making a white brittle alloy that can be polished to make a highly reflective surface. It is used primarily to make different kinds of mirrors including early reflecting telescope optical mirrors. Speculum metal can also be used as the metallic coating on glass mirrors (as opposed to silver or aluminium) giving a reflectivity of 68% at 6000 angstroms when evaporated onto the surface.
Phosphor bronze is an alloy of copper with 3.5 to 10% of tin and a significant phosphorus content of up to 1%. The phosphorus is added as deoxidizing agent during melting. These alloys are notable for their toughness, strength, low coefficient of friction, and fine grain. The phosphorus also improves the fluidity of the molten metal and thereby improves the castability, and improves mechanical properties by cleaning up the grain boundaries.
Bell metal is a hard alloy used for making bells. It is a form of bronze, usually approximately 3:1 ratio of copper to tin (78% copper, 22% tin). Bell metal ore is a sulfide of tin, copper, and iron; and the mineral stannite.
Gunmetal, also known as red brass in the United States, is a type of bronze – an alloy of copper, tin, and zinc. Originally used chiefly for making guns, gunmetal was superseded by steel. Gunmetal is resistant to corrosion from steam and salt water. Gunmetals produced for different purposes vary slightly in composition. In some cases, the alloy may be composed only from copper and tin, or from copper, tin, and lead.
Aluminium bronze is a type of bronze in which aluminium is the main alloying metal added to copper. A variety of aluminium bronzes of differing compositions have found industrial use, with most ranging from 5% to 11% aluminium by weight, the remaining mass being copper; other alloying agents such as iron, nickel, manganese, and silicon are also sometimes added to aluminium bronzes.
It is a common misconception that pre-Columbian Americas lacked bronze and thus were not able to deploy hardened copper alloys. However, copper alloys are reported as ‘guanín’ by Columbus, a loan word borrowed from the Taino . This misconception may well arise because tin, the common component of Eurasian bronze (although common in Bolivia), is rare in the Caribbean basin.
Bronzing is a process by which a bronze-like surface is applied to other materials (metallic or non-metallic). Some bronzing processes are merely simulated finishes applied to existing metal surfaces, or coatings of powdered metal that give the appearance of a solid metal surface. In other cases, an actual layer of heavy copper is electroplated onto an object to produce a bronze-like surface. This electroplating is the method traditionally used for "bronzing" of baby shoes.
The Biertan Donarium is a fourth century Christian votive object found near the town of Biertan, in Transylvania, Romania. Made out of bronze in the shape of a Labarum, it has the Latin text, which can be approximatively translated as "I, Zenovius, offered this gift". It was found in 1775 in the Chimdru forest, about 5 km south of Biertan and it was part of the collections of Baron Samuel von Brukenthal, nowadays being part of the exhibits of the Brukenthal National Museum.
Bismuth bronze is a bronze alloy with a composition of 52 parts copper, 30 parts nickel, 12 parts zinc, 5 parts lead, and 1 part bismuth. It is able to hold a good polish and so is sometimes used in light reflectors and mirrors.