In a breakthrough, researchers have developed world’s lightest gold nugget that is lighter than water and in fact, it is nearly as light as air. The 20 carat gold foam is so light that it can float on milk foam, scientists demonstrated it. According to its developer, the newly made gold foam is nearly 1,000 times lighter than all the known conventional forms of the gold.
What’s special about the new lightweight gold nugget is that although it is as light as air but one cannot differentiate between the heavy gold and this lightweight gold by naked eyes.
Designing such thing was a daunting task and lead researcher Raffaele Mezzenga, Professor of Food and Soft Materials at ETH Zurich, came up with an idea and worked upon it. He knew that for a nugget to be 1000 times lighter than the conventional methods, the internal structure should be mostly empty. So, study authors made a porous structure by using a three-dimensional mesh which contains only 2 percent metal while the rest 98 percent is air. The resulting compound was an aerogel that is very delicate and malleable by human hand.
While explaining the composition of 2 percent metal, researchers said that four-fifth part is pure gold while remaining one-fourth part is milk protein fibres that makes it a 20 carat gold nugget.
Another crucial step was to create a porous material. Researchers formed the aerogel by creating nanometre-fine protein fibre and mixing it with the solution of gold salt. Nanometre-fine protein fibres are made by heating the milk proteins. According to Raffaele Mezzanga, these protein fibres form a crystalline structure with the gold salt and gives a solid gold like appearance while it is 1000 times lighter than normal gold.
For drying the aerogel, researchers exposed the content with Carbon Dioxide that slowly absorbed the moisture without causing any harm to the mixture and gold composition. We can alter the colour of the gold nuggets by changing the size of gold salt while mixing it nanometre-fine protein fibre.
The study was published in the journal Advanced Materials.