Niobium: a unique coin metal

After two years of development, the Austrian Mint issued a Silver Niobium coin for the first time in 2003. The fruit of a collaboration with Plansee, a Tyrolese company specialising in high-performance materials, our Silver Niobium coins are a global innovation and have proven extremely popular among collectors and investors and also as gifts.

Metals used in the manufacture of coins must have certain requisite characteristics. They have to have a homogeneous surface, be malleable for rimming and striking, be resistant to corrosion and relatively common. In addition to these qualities, although naturally light grey in colour, after special treatment niobium develops a particularly precious and colourful appearance, making it an increasingly popular component in the manufacture of jewellery.

The beauty of niobium is that colour does not need to be applied to it. By means of ‘anodized oxidation’, a very thin oxide layer is produced on the coin surface and subsequent light refraction enables different colours to arise. Some imitators have tried to reproduce this effect by adding colour but it only damages the transparency and brilliance of the metal surface.

“Our customers love the unique appearance of these coins. The wonderful glow of their colours makes people envisage all kinds of different uses for niobium,” says Alfred Gnadenberger, head of collector coins at the Austrian Mint.  “Among others, I’ve been asked about its suitability for wedding rings.”

Discovered in 1801, niobium is stable in air and can be rolled and forged at room temperature. It took some 60 years to succeed in making it of use in industrial applications, however. Its high melting point of 2,468°C means that it is mainly used in the steel industry, while its unique properties such as superconductivity – at temperatures in the region of absolute zero it loses its electrical resistance and can conduct current without loss – also mean that niobium is a favoured component in the aerospace industry.