Researchers at the Swiss Federal Institute of Technology have developed a new form of real 20 carat gold which is so light that it can float over milk foam.
The gold is in the form of a three-dimensional mesh of gold that consists mostly of pores. It is the lightest gold nugget ever created.
"The so-called aerogel is a thousand times lighter than conventional gold alloys. It is lighter than water and almost as light as air," said lead reseracher professor Raffaele Mezzenga.
The new gold form can hardly be differentiated from conventional gold with the naked eye - the aerogel even has a metallic shine.
But in contrast to its conventional form, it is soft and malleable by hand.
It consists of 98 parts air and only two parts of solid material. Of this solid material, more than four-fifths are gold and less than one-fifth is milk protein fibrils. This corresponds to around 20 carat gold.
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The new material could be used in many of the applications where gold is currently being used, said Mezzenga. Applications in watches and jewellery are only one possibility.
Another application demonstrated by the scientists is chemical catalysis: since the highly porous material has a huge surface, chemical reactions that depend on the presence of gold can be run in a very efficient manner.
The findings were published in the journal Advanced Materials.