Gold

Gold has the symbol Au. It is a chemical element, Group 11 (Ib), Period 6, of the periodic table of the elements. It is a dense yellow precious metal that is very durable yet highly malleable. It does not tarnish or corrode and is usually found naturally in a relatively pure form.

It is widespread in low concentration in all igneous rocks, often found in very small amounts with copper and lead deposits, and as such can be a by-product in the refining of those metals. Larger masses of gold-bearing rock are rare but hydrothermal veins, associated with quartz and pyrite (fool’s gold) derive from the weathering of gold-bearing rocks. It exists mostly in its native state, chemically uncombined, except with tellurium, selenium, and bismuth. The only naturally occurring isotope is gold-197.

It has had high value from the earliest periods, with goldsmith examples in nearly perfect condition, from ancient Egyptian, Minoan, Assyrian, and Etruscan artisans. It a highly respected material for jewellery as well as a highly regarded reserve asset, with approximately 45 percent of all the world’s gold held by governments and central banks.

As a highly conductive metal that remains corrosion free, an important industrial use is in the manufacture of electronics. As it can carry tiny currents it is used in connectors, switch and relay contacts, soldered joints, connecting wires and connection strips, many of which may be used in the service equipment of modern buildings.

Gold has been used in buildings primarily for decoration. Because it is very malleable it can be shaped into thin layers or leafs, which are used for gilding, or laying gold leaf over materials, giving the appearance of solid gold. A process believed to have originated in Turkey more than 8,000 years ago, and commonly used by the ancient Egyptians, the Phoenecians, and eventually the early Europeans for sculptural elements in buildings. Some of the best examples can be found at the golden temple (Harmandir Sahib) in the city of Amritsar, Punjab, India, the Shwedagon Pagoda (Shwedagon Zedi Daw or Golden Dagon Pagoda) located in Yangon, Myanmar or the Dome of the Rock (Qubbat a-akhra) in Jerusalem.

More recently gold was used for another reason in the famous Sydney Opera House to limit the heat and glare of the sun. Gold is an excellent reflector of electromagnetic radiation (including solar radiation, visible light, and radio waves) and because of its malleability it can be beaten to be semi-transparent and used in window glazing. It was used for the same reason in the Royal Bank Plaza Towers in Toronto, Canada as well as the Trump International Hotel and Tower in Las Vegas.

Today there are considered to be 3 different types of gold:

• Yellow gold is naturally occurring and is the purest form of the metal. For jewellery, it is made into an alloy by combining pure gold with metals such as zinc and copper.
• White gold is mixed with palladium or nickel to give it a colour close to silver or platinum.
• Rose gold is an alloy including about 25% copper, which gives it a pinkish colour.

[edit] Related articles on Designing Buildings

• Brass.
• Cosmati work.
• Decoration.
• Gilding.
• Golden Temple, Amritsar.
• Goldsmith.
• Historic paintwork.
• Metal.
• Paint.
• Restoring Orleans House Octagon.
• St Peters Basilica.
• Silver.
• Surface finishes.
• Types of metal.

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