Silver. Silver has been employed in art, highlighting its precious nature, malleability, and ability to create visually stunning works. Thin sheets of beaten silver, called silver leaf gilding, have been applied to surfaces like wood, metal, or parchment to embellish sculptures, altarpieces, and illuminated manuscripts. Silver has been used to create sculptures such as altarpieces, crucifixes, and statuettes of saints, often commissioned by churches or wealthy patrons. Intricately crafted silver objects have been created for decorative and functional purposes, showcasing wealth and status. Relief images of individuals or commemorative scenes have been created in silver, often commissioned to celebrate events or honor achievements. Small-scale silver sculptures depict mythological, historical, or allegorical figures, prized for their intricate detailing and craftsmanship. Silver has been combined with other materials like wood, stone, or bronze to create sculptures where silver may be used as an accent or for specific elements. The metal is found in the Earth's crust in the pure, free elemental form, as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as 0.940 fine. As one of the seven metals of antiquity, silver has had an enduring role in most human Other than in currency and as an investment medium, silver is used in solar panels, water filtration, jewellery, ornaments, high-value tableware and utensils, in electrical contacts and conductors, in specialized mirrors, window coatings, in catalysis of chemical reactions, as a colorant in stained glass, and in specialized confectionery. Its compounds are used in photographic and X-ray film. Dilute solutions of silver nitrate and other silver compounds are used as disinfectants and microbiocides, added to bandages, wound-dressings, catheters, and other medical instruments. Silver is a relatively soft and extremely ductile and malleable transition metal, though it is slightly less malleable than gold. Silver crystallizes in a face-centered cubic lattice with bulk coordination number 12, where only the single 5s electron is delocalized, similarly to copper and gold. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant, white, metallic luster that can take a high polish, and which is so characteristic that the name of the metal itself has become a color name. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm. At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm. Very high electrical and thermal conductivity are common to the elements in group 11, because their single s electron is free and does not interact with the filled d subshell, as such interactions lower electron mobility. The thermal conductivity of silver is among the highest of all materials, although the thermal conductivity of carbon and superfluid helium-4 are higher. The electrical conductivity of silver is the highest of all metals, greater even than copper. Silver also has the lowest contact resistance of any metal. Silver is rarely used for its electrical conductivity, due to its high cost, although an exception is in radio-frequency engineering, particularly at VHF and higher frequencies where silver plating improves electrical conductivity because those currents tend to flow on the surface of conductors rather than through the interior. During World War II in the US, 13540 tons of silver were used for the electromagnets in calutrons for enriching uranium, mainly because of the wartime shortage of copper. Silver readily forms alloys with copper, gold, and zinc. Zinc-silver alloys with low zinc concentration may be considered as face-centred cubic solid solutions of zinc in silver, as the structure of the silver is largely unchanged while the electron concentration rises as more zinc is added.