The ethical gold rush: Gilded age for guilt-free jewellery

Forget how many carats—how ethical is your gold? As high-end consumers demand to know the origin of their treasures, some jewellers are ensuring they use responsibly sourced, eco-friendly or recycled gold.

The golden path towards new two-dimensional semiconductors

Two-dimensional (2-D) semiconductors are promising for quantum computing and future electronics. Now, researchers can convert metallic gold into semiconductor and customize the material atom-by-atom on boron nitride nanotubes.

From medicine to nanotechnology: How gold quietly shapes our world

The periodic table of chemical elements turns 150 this year. The anniversary is a chance to shine a light on particular elements – some of which seem ubiquitous but which ordinary people beyond the world of chemistry probably ...

Gold soaks up boron, spits out borophene

In the heat of a furnace, boron atoms happily dive into a bath of gold. And when things get cool, they resurface as coveted borophene.

Researchers report new light-activated micro pump

Even the smallest mechanical pumps have limitations, from the complex microfabrication techniques required to make them to the fact that there are limits on how small they can be. Researchers have announced a potential solution—a ...

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Gold (pronounced /ˈɡoʊld/) is a chemical element with the symbol Au (Latin: aurum) and an atomic number of 79. It has been a highly sought-after precious metal in jewelry, in sculpture, and for ornamentation since the beginning of recorded history. The metal occurs as nuggets or grains in rocks, in veins and in alluvial deposits. Gold is dense, soft, shiny and the most malleable and ductile pure metal known. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. It is one of the coinage metals and formed the basis for the gold standard used before the collapse of the Bretton Woods system in 1971.

At the end of 2006, it was estimated that all the gold ever mined totaled 158,000 tonnes. This can be represented by a cube with an edge length of just 20.2 meters. Modern industrial uses include dentistry and electronics, where gold has traditionally found use because of its good resistance to oxidative corrosion and excellent quality as a conductor of electricity. Chemically, gold is a transition metal and can form trivalent and univalent cations upon solvation. At STP it is attacked by aqua regia (a mixture of acids), forming chloroauric acid and by alkaline solutions of cyanide but not by single acids such as hydrochloric, nitric or sulfuric acids. Gold dissolves in mercury, forming amalgam alloys, but does not react with it. Since gold is insoluble in nitric acid which will dissolve silver and base metals, this is exploited as the basis of the gold refining technique known as "inquartation and parting". Nitric acid has long been used to confirm the presence of gold in items, and this is the origin of the colloquial term "acid test", referring to a gold standard test for genuine value.

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