Niobium

What is Niobium?

It's a metal that's durable and hypoallergenic and can be anodised to achieve beautiful colours! Niobium is a rare and precious material that's lightweight and strong — perfect for jewellery!

An element in the periodic table with the symbol Nb. It's a transition metal and in its pure form can be cold worked. It has to be annealed (softened) under very specific conditions but because it work hardens so slowly, it can be formed using chasing and repoussé without annealing it.

Close up of chasing and repoussé on the "Fool's Gold" Brooch showing the different anodised colours.

Blue anodised niobium pendant.

Alice's research into titanium and niobium as an alternative source of colour to gemstones has lead her to explore the technique of anodising.

 

 

The colour chart below shows the range of colours that niobium can be anodised to.

Niobium anodised colours at different voltages

How does anodising work?

  • It uses a process called electrolysis which passes an electric current through a solution called an electrolyte. Alice uses MgSO4, otherwise known as epsom salts, for her electrolyte.

  • The niobium (or titanium) piece is attached to a crocodile clip which forms the anode, and stainless steel is used as the cathode.

  • As an electric current passes through the electrolyte, a transparent oxide layer forms on the surface of the niobium.

  • The higher the voltage, the thicker the oxide layer, creating different colours as shown above.

    Anodising niobium diagram

    Refraction of light on niobium oxide layer

    Diagram showing the anodising process.

    Refraction of light creating an "optical illusion".