As well as electrical conductivity and corrosion resistance, what other properties of gold are useful?

Gold, like other important metals, has some unique physical, chemical, and optical attributes that mean it is the best material for a certain application. For example, gold is very ductile and for some electronic components like bonding wires, the ability to draw gold alloys into extremely thin diameters without breaking is a critical property in the manufacturing process.

Gold is also extremely malleable, so in the annealed state it can be hammered cold into a translucent wafer 0.000013 cm thick. One ounce of gold can be beaten into a sheet covering over 9 square metres and 0.000018 cm thick. Bulk gold has a familiar yellow colour of course. However, when particles of gold are small enough their colour is actually ruby red.

This effect has been used to colour glass red, even in Roman times, but if such tiny particles are allowed to coalesce in a controlled fashion, their colour can be varied from pink through violet to blue. This unique property has been used as a colorimetric indicator in home pregnancy tests.

• Back to the questions